/*------------------------------------------------------------------------- * * xlog.c * PostgreSQL transaction log manager * * * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * src/backend/access/transam/xlog.c * *------------------------------------------------------------------------- */ #include "postgres.h" #include #include #include #include #include #include #include #include #include "access/clog.h" #include "access/multixact.h" #include "access/subtrans.h" #include "access/transam.h" #include "access/tuptoaster.h" #include "access/twophase.h" #include "access/xact.h" #include "access/xlog_internal.h" #include "access/xlogutils.h" #include "catalog/catversion.h" #include "catalog/pg_control.h" #include "catalog/pg_database.h" #include "libpq/pqsignal.h" #include "miscadmin.h" #include "pgstat.h" #include "postmaster/bgwriter.h" #include "postmaster/startup.h" #include "replication/walreceiver.h" #include "replication/walsender.h" #include "storage/bufmgr.h" #include "storage/fd.h" #include "storage/ipc.h" #include "storage/latch.h" #include "storage/pmsignal.h" #include "storage/predicate.h" #include "storage/proc.h" #include "storage/procarray.h" #include "storage/reinit.h" #include "storage/smgr.h" #include "storage/spin.h" #include "utils/builtins.h" #include "utils/guc.h" #include "utils/ps_status.h" #include "utils/relmapper.h" #include "utils/snapmgr.h" #include "utils/timestamp.h" #include "pg_trace.h" /* File path names (all relative to $PGDATA) */ #define RECOVERY_COMMAND_FILE "recovery.conf" #define RECOVERY_COMMAND_DONE "recovery.done" #define PROMOTE_SIGNAL_FILE "promote" /* User-settable parameters */ int CheckPointSegments = 3; int wal_keep_segments = 0; int XLOGbuffers = -1; int XLogArchiveTimeout = 0; bool XLogArchiveMode = false; char *XLogArchiveCommand = NULL; bool EnableHotStandby = false; bool fullPageWrites = true; bool log_checkpoints = false; int sync_method = DEFAULT_SYNC_METHOD; int wal_level = WAL_LEVEL_MINIMAL; #ifdef WAL_DEBUG bool XLOG_DEBUG = false; #endif /* * XLOGfileslop is the maximum number of preallocated future XLOG segments. * When we are done with an old XLOG segment file, we will recycle it as a * future XLOG segment as long as there aren't already XLOGfileslop future * segments; else we'll delete it. This could be made a separate GUC * variable, but at present I think it's sufficient to hardwire it as * 2*CheckPointSegments+1. Under normal conditions, a checkpoint will free * no more than 2*CheckPointSegments log segments, and we want to recycle all * of them; the +1 allows boundary cases to happen without wasting a * delete/create-segment cycle. */ #define XLOGfileslop (2*CheckPointSegments + 1) /* * GUC support */ const struct config_enum_entry wal_level_options[] = { {"minimal", WAL_LEVEL_MINIMAL, false}, {"archive", WAL_LEVEL_ARCHIVE, false}, {"hot_standby", WAL_LEVEL_HOT_STANDBY, false}, {NULL, 0, false} }; const struct config_enum_entry sync_method_options[] = { {"fsync", SYNC_METHOD_FSYNC, false}, #ifdef HAVE_FSYNC_WRITETHROUGH {"fsync_writethrough", SYNC_METHOD_FSYNC_WRITETHROUGH, false}, #endif #ifdef HAVE_FDATASYNC {"fdatasync", SYNC_METHOD_FDATASYNC, false}, #endif #ifdef OPEN_SYNC_FLAG {"open_sync", SYNC_METHOD_OPEN, false}, #endif #ifdef OPEN_DATASYNC_FLAG {"open_datasync", SYNC_METHOD_OPEN_DSYNC, false}, #endif {NULL, 0, false} }; /* * Statistics for current checkpoint are collected in this global struct. * Because only the background writer or a stand-alone backend can perform * checkpoints, this will be unused in normal backends. */ CheckpointStatsData CheckpointStats; /* * ThisTimeLineID will be same in all backends --- it identifies current * WAL timeline for the database system. */ TimeLineID ThisTimeLineID = 0; /* * Are we doing recovery from XLOG? * * This is only ever true in the startup process; it should be read as meaning * "this process is replaying WAL records", rather than "the system is in * recovery mode". It should be examined primarily by functions that need * to act differently when called from a WAL redo function (e.g., to skip WAL * logging). To check whether the system is in recovery regardless of which * process you're running in, use RecoveryInProgress() but only after shared * memory startup and lock initialization. */ bool InRecovery = false; /* Are we in Hot Standby mode? Only valid in startup process, see xlog.h */ HotStandbyState standbyState = STANDBY_DISABLED; static XLogRecPtr LastRec; /* * During recovery, lastFullPageWrites keeps track of full_page_writes that * the replayed WAL records indicate. It's initialized with full_page_writes * that the recovery starting checkpoint record indicates, and then updated * each time XLOG_FPW_CHANGE record is replayed. */ static bool lastFullPageWrites; /* * Local copy of SharedRecoveryInProgress variable. True actually means "not * known, need to check the shared state". */ static bool LocalRecoveryInProgress = true; /* * Local copy of SharedHotStandbyActive variable. False actually means "not * known, need to check the shared state". */ static bool LocalHotStandbyActive = false; /* * Local state for XLogInsertAllowed(): * 1: unconditionally allowed to insert XLOG * 0: unconditionally not allowed to insert XLOG * -1: must check RecoveryInProgress(); disallow until it is false * Most processes start with -1 and transition to 1 after seeing that recovery * is not in progress. But we can also force the value for special cases. * The coding in XLogInsertAllowed() depends on the first two of these states * being numerically the same as bool true and false. */ static int LocalXLogInsertAllowed = -1; /* Are we recovering using offline XLOG archives? */ static bool InArchiveRecovery = false; /* Was the last xlog file restored from archive, or local? */ static bool restoredFromArchive = false; /* options taken from recovery.conf for archive recovery */ static char *recoveryRestoreCommand = NULL; static char *recoveryEndCommand = NULL; static char *archiveCleanupCommand = NULL; static RecoveryTargetType recoveryTarget = RECOVERY_TARGET_UNSET; static bool recoveryTargetInclusive = true; static bool recoveryPauseAtTarget = true; static TransactionId recoveryTargetXid; static TimestampTz recoveryTargetTime; static char *recoveryTargetName; /* options taken from recovery.conf for XLOG streaming */ static bool StandbyMode = false; static char *PrimaryConnInfo = NULL; static char *TriggerFile = NULL; /* if recoveryStopsHere returns true, it saves actual stop xid/time/name here */ static TransactionId recoveryStopXid; static TimestampTz recoveryStopTime; static char recoveryStopName[MAXFNAMELEN]; static bool recoveryStopAfter; /* * During normal operation, the only timeline we care about is ThisTimeLineID. * During recovery, however, things are more complicated. To simplify life * for rmgr code, we keep ThisTimeLineID set to the "current" timeline as we * scan through the WAL history (that is, it is the line that was active when * the currently-scanned WAL record was generated). We also need these * timeline values: * * recoveryTargetTLI: the desired timeline that we want to end in. * * recoveryTargetIsLatest: was the requested target timeline 'latest'? * * expectedTLIs: an integer list of recoveryTargetTLI and the TLIs of * its known parents, newest first (so recoveryTargetTLI is always the * first list member). Only these TLIs are expected to be seen in the WAL * segments we read, and indeed only these TLIs will be considered as * candidate WAL files to open at all. * * curFileTLI: the TLI appearing in the name of the current input WAL file. * (This is not necessarily the same as ThisTimeLineID, because we could * be scanning data that was copied from an ancestor timeline when the current * file was created.) During a sequential scan we do not allow this value * to decrease. */ static TimeLineID recoveryTargetTLI; static bool recoveryTargetIsLatest = false; static List *expectedTLIs; static TimeLineID curFileTLI; /* * ProcLastRecPtr points to the start of the last XLOG record inserted by the * current backend. It is updated for all inserts. XactLastRecEnd points to * end+1 of the last record, and is reset when we end a top-level transaction, * or start a new one; so it can be used to tell if the current transaction has * created any XLOG records. */ static XLogRecPtr ProcLastRecPtr = {0, 0}; XLogRecPtr XactLastRecEnd = {0, 0}; /* * RedoRecPtr is this backend's local copy of the REDO record pointer * (which is almost but not quite the same as a pointer to the most recent * CHECKPOINT record). We update this from the shared-memory copy, * XLogCtl->Insert.RedoRecPtr, whenever we can safely do so (ie, when we * hold the Insert lock). See XLogInsert for details. We are also allowed * to update from XLogCtl->Insert.RedoRecPtr if we hold the info_lck; * see GetRedoRecPtr. A freshly spawned backend obtains the value during * InitXLOGAccess. */ static XLogRecPtr RedoRecPtr; /* * RedoStartLSN points to the checkpoint's REDO location which is specified * in a backup label file, backup history file or control file. In standby * mode, XLOG streaming usually starts from the position where an invalid * record was found. But if we fail to read even the initial checkpoint * record, we use the REDO location instead of the checkpoint location as * the start position of XLOG streaming. Otherwise we would have to jump * backwards to the REDO location after reading the checkpoint record, * because the REDO record can precede the checkpoint record. */ static XLogRecPtr RedoStartLSN = {0, 0}; /*---------- * Shared-memory data structures for XLOG control * * LogwrtRqst indicates a byte position that we need to write and/or fsync * the log up to (all records before that point must be written or fsynced). * LogwrtResult indicates the byte positions we have already written/fsynced. * These structs are identical but are declared separately to indicate their * slightly different functions. * * To read XLogCtl->LogwrtResult, you must hold either info_lck or * WALWriteLock. To update it, you need to hold both locks. The point of * this arrangement is that the value can be examined by code that already * holds WALWriteLock without needing to grab info_lck as well. In addition * to the shared variable, each backend has a private copy of LogwrtResult, * which is updated when convenient. * * The request bookkeeping is simpler: there is a shared XLogCtl->LogwrtRqst * (protected by info_lck), but we don't need to cache any copies of it. * * info_lck is only held long enough to read/update the protected variables, * so it's a plain spinlock. The other locks are held longer (potentially * over I/O operations), so we use LWLocks for them. These locks are: * * WALInsertLock: must be held to insert a record into the WAL buffers. * * WALWriteLock: must be held to write WAL buffers to disk (XLogWrite or * XLogFlush). * * ControlFileLock: must be held to read/update control file or create * new log file. * * CheckpointLock: must be held to do a checkpoint or restartpoint (ensures * only one checkpointer at a time; currently, with all checkpoints done by * the checkpointer, this is just pro forma). * *---------- */ typedef struct XLogwrtRqst { XLogRecPtr Write; /* last byte + 1 to write out */ XLogRecPtr Flush; /* last byte + 1 to flush */ } XLogwrtRqst; typedef struct XLogwrtResult { XLogRecPtr Write; /* last byte + 1 written out */ XLogRecPtr Flush; /* last byte + 1 flushed */ } XLogwrtResult; /* * Shared state data for XLogInsert. */ typedef struct XLogCtlInsert { XLogRecPtr PrevRecord; /* start of previously-inserted record */ int curridx; /* current block index in cache */ XLogPageHeader currpage; /* points to header of block in cache */ char *currpos; /* current insertion point in cache */ XLogRecPtr RedoRecPtr; /* current redo point for insertions */ bool forcePageWrites; /* forcing full-page writes for PITR? */ /* * fullPageWrites is the master copy used by all backends to determine * whether to write full-page to WAL, instead of using process-local one. * This is required because, when full_page_writes is changed by SIGHUP, * we must WAL-log it before it actually affects WAL-logging by backends. * Checkpointer sets at startup or after SIGHUP. */ bool fullPageWrites; /* * exclusiveBackup is true if a backup started with pg_start_backup() is * in progress, and nonExclusiveBackups is a counter indicating the number * of streaming base backups currently in progress. forcePageWrites is set * to true when either of these is non-zero. lastBackupStart is the latest * checkpoint redo location used as a starting point for an online backup. */ bool exclusiveBackup; int nonExclusiveBackups; XLogRecPtr lastBackupStart; } XLogCtlInsert; /* * Shared state data for XLogWrite/XLogFlush. */ typedef struct XLogCtlWrite { int curridx; /* cache index of next block to write */ pg_time_t lastSegSwitchTime; /* time of last xlog segment switch */ } XLogCtlWrite; /* * Total shared-memory state for XLOG. */ typedef struct XLogCtlData { /* Protected by WALInsertLock: */ XLogCtlInsert Insert; /* Protected by info_lck: */ XLogwrtRqst LogwrtRqst; uint32 ckptXidEpoch; /* nextXID & epoch of latest checkpoint */ TransactionId ckptXid; XLogRecPtr asyncXactLSN; /* LSN of newest async commit/abort */ uint32 lastRemovedLog; /* latest removed/recycled XLOG segment */ uint32 lastRemovedSeg; /* Protected by WALWriteLock: */ XLogCtlWrite Write; /* * Protected by info_lck and WALWriteLock (you must hold either lock to * read it, but both to update) */ XLogwrtResult LogwrtResult; /* * These values do not change after startup, although the pointed-to pages * and xlblocks values certainly do. Permission to read/write the pages * and xlblocks values depends on WALInsertLock and WALWriteLock. */ char *pages; /* buffers for unwritten XLOG pages */ XLogRecPtr *xlblocks; /* 1st byte ptr-s + XLOG_BLCKSZ */ int XLogCacheBlck; /* highest allocated xlog buffer index */ TimeLineID ThisTimeLineID; TimeLineID RecoveryTargetTLI; /* * archiveCleanupCommand is read from recovery.conf but needs to be in * shared memory so that the checkpointer process can access it. */ char archiveCleanupCommand[MAXPGPATH]; /* * SharedRecoveryInProgress indicates if we're still in crash or archive * recovery. Protected by info_lck. */ bool SharedRecoveryInProgress; /* * SharedHotStandbyActive indicates if we're still in crash or archive * recovery. Protected by info_lck. */ bool SharedHotStandbyActive; /* * WalWriterSleeping indicates whether the WAL writer is currently in * low-power mode (and hence should be nudged if an async commit occurs). * Protected by info_lck. */ bool WalWriterSleeping; /* * recoveryWakeupLatch is used to wake up the startup process to continue * WAL replay, if it is waiting for WAL to arrive or failover trigger file * to appear. */ Latch recoveryWakeupLatch; /* * During recovery, we keep a copy of the latest checkpoint record here. * Used by the background writer when it wants to create a restartpoint. * * Protected by info_lck. */ XLogRecPtr lastCheckPointRecPtr; CheckPoint lastCheckPoint; /* end+1 of the last record replayed (or being replayed) */ XLogRecPtr replayEndRecPtr; /* end+1 of the last record replayed */ XLogRecPtr recoveryLastRecPtr; /* timestamp of last COMMIT/ABORT record replayed (or being replayed) */ TimestampTz recoveryLastXTime; /* * timestamp of when we started replaying the current chunk of WAL data, * only relevant for replication or archive recovery */ TimestampTz currentChunkStartTime; /* end of the last record restored from the archive */ XLogRecPtr restoreLastRecPtr; /* Are we requested to pause recovery? */ bool recoveryPause; /* * lastFpwDisableRecPtr points to the start of the last replayed * XLOG_FPW_CHANGE record that instructs full_page_writes is disabled. */ XLogRecPtr lastFpwDisableRecPtr; slock_t info_lck; /* locks shared variables shown above */ } XLogCtlData; static XLogCtlData *XLogCtl = NULL; /* * We maintain an image of pg_control in shared memory. */ static ControlFileData *ControlFile = NULL; /* * Macros for managing XLogInsert state. In most cases, the calling routine * has local copies of XLogCtl->Insert and/or XLogCtl->Insert->curridx, * so these are passed as parameters instead of being fetched via XLogCtl. */ /* Free space remaining in the current xlog page buffer */ #define INSERT_FREESPACE(Insert) \ (XLOG_BLCKSZ - ((Insert)->currpos - (char *) (Insert)->currpage)) /* Construct XLogRecPtr value for current insertion point */ #define INSERT_RECPTR(recptr,Insert,curridx) \ ( \ (recptr).xlogid = XLogCtl->xlblocks[curridx].xlogid, \ (recptr).xrecoff = \ XLogCtl->xlblocks[curridx].xrecoff - INSERT_FREESPACE(Insert) \ ) #define PrevBufIdx(idx) \ (((idx) == 0) ? XLogCtl->XLogCacheBlck : ((idx) - 1)) #define NextBufIdx(idx) \ (((idx) == XLogCtl->XLogCacheBlck) ? 0 : ((idx) + 1)) /* * Private, possibly out-of-date copy of shared LogwrtResult. * See discussion above. */ static XLogwrtResult LogwrtResult = {{0, 0}, {0, 0}}; /* * Codes indicating where we got a WAL file from during recovery, or where * to attempt to get one. These are chosen so that they can be OR'd together * in a bitmask state variable. */ #define XLOG_FROM_ARCHIVE (1<<0) /* Restored using restore_command */ #define XLOG_FROM_PG_XLOG (1<<1) /* Existing file in pg_xlog */ #define XLOG_FROM_STREAM (1<<2) /* Streamed from master */ /* * openLogFile is -1 or a kernel FD for an open log file segment. * When it's open, openLogOff is the current seek offset in the file. * openLogId/openLogSeg identify the segment. These variables are only * used to write the XLOG, and so will normally refer to the active segment. */ static int openLogFile = -1; static uint32 openLogId = 0; static uint32 openLogSeg = 0; static uint32 openLogOff = 0; /* * These variables are used similarly to the ones above, but for reading * the XLOG. Note, however, that readOff generally represents the offset * of the page just read, not the seek position of the FD itself, which * will be just past that page. readLen indicates how much of the current * page has been read into readBuf, and readSource indicates where we got * the currently open file from. */ static int readFile = -1; static uint32 readId = 0; static uint32 readSeg = 0; static uint32 readOff = 0; static uint32 readLen = 0; static int readSource = 0; /* XLOG_FROM_* code */ /* * Keeps track of which sources we've tried to read the current WAL * record from and failed. */ static int failedSources = 0; /* OR of XLOG_FROM_* codes */ /* * These variables track when we last obtained some WAL data to process, * and where we got it from. (XLogReceiptSource is initially the same as * readSource, but readSource gets reset to zero when we don't have data * to process right now.) */ static TimestampTz XLogReceiptTime = 0; static int XLogReceiptSource = 0; /* XLOG_FROM_* code */ /* Buffer for currently read page (XLOG_BLCKSZ bytes) */ static char *readBuf = NULL; /* Buffer for current ReadRecord result (expandable) */ static char *readRecordBuf = NULL; static uint32 readRecordBufSize = 0; /* State information for XLOG reading */ static XLogRecPtr ReadRecPtr; /* start of last record read */ static XLogRecPtr EndRecPtr; /* end+1 of last record read */ static TimeLineID lastPageTLI = 0; static XLogRecPtr minRecoveryPoint; /* local copy of * ControlFile->minRecoveryPoint */ static bool updateMinRecoveryPoint = true; /* * Have we reached a consistent database state? In crash recovery, we have * to replay all the WAL, so reachedConsistency is never set. During archive * recovery, the database is consistent once minRecoveryPoint is reached. */ bool reachedConsistency = false; static bool InRedo = false; /* Have we launched bgwriter during recovery? */ static bool bgwriterLaunched = false; /* * Information logged when we detect a change in one of the parameters * important for Hot Standby. */ typedef struct xl_parameter_change { int MaxConnections; int max_prepared_xacts; int max_locks_per_xact; int wal_level; } xl_parameter_change; /* logs restore point */ typedef struct xl_restore_point { TimestampTz rp_time; char rp_name[MAXFNAMELEN]; } xl_restore_point; static void XLogArchiveNotify(const char *xlog); static void XLogArchiveNotifySeg(uint32 log, uint32 seg); static bool XLogArchiveCheckDone(const char *xlog); static bool XLogArchiveIsBusy(const char *xlog); static void XLogArchiveCleanup(const char *xlog); static void readRecoveryCommandFile(void); static void exitArchiveRecovery(TimeLineID endTLI, uint32 endLogId, uint32 endLogSeg); static bool recoveryStopsHere(XLogRecord *record, bool *includeThis); static void recoveryPausesHere(void); static void SetLatestXTime(TimestampTz xtime); static void SetCurrentChunkStartTime(TimestampTz xtime); static void CheckRequiredParameterValues(void); static void XLogReportParameters(void); static void LocalSetXLogInsertAllowed(void); static void CheckPointGuts(XLogRecPtr checkPointRedo, int flags); static void KeepLogSeg(XLogRecPtr recptr, uint32 *logId, uint32 *logSeg); static bool XLogCheckBuffer(XLogRecData *rdata, bool doPageWrites, XLogRecPtr *lsn, BkpBlock *bkpb); static bool AdvanceXLInsertBuffer(bool new_segment); static bool XLogCheckpointNeeded(uint32 logid, uint32 logseg); static void XLogWrite(XLogwrtRqst WriteRqst, bool flexible, bool xlog_switch); static bool InstallXLogFileSegment(uint32 *log, uint32 *seg, char *tmppath, bool find_free, int *max_advance, bool use_lock); static int XLogFileRead(uint32 log, uint32 seg, int emode, TimeLineID tli, int source, bool notexistOk); static int XLogFileReadAnyTLI(uint32 log, uint32 seg, int emode, int sources); static bool XLogPageRead(XLogRecPtr *RecPtr, int emode, bool fetching_ckpt, bool randAccess); static int emode_for_corrupt_record(int emode, XLogRecPtr RecPtr); static void XLogFileClose(void); static bool RestoreArchivedFile(char *path, const char *xlogfname, const char *recovername, off_t expectedSize); static void ExecuteRecoveryCommand(char *command, char *commandName, bool failOnerror); static void PreallocXlogFiles(XLogRecPtr endptr); static void RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr); static void UpdateLastRemovedPtr(char *filename); static void ValidateXLOGDirectoryStructure(void); static void CleanupBackupHistory(void); static void UpdateMinRecoveryPoint(XLogRecPtr lsn, bool force); static XLogRecord *ReadRecord(XLogRecPtr *RecPtr, int emode, bool fetching_ckpt); static void CheckRecoveryConsistency(void); static bool ValidXLOGHeader(XLogPageHeader hdr, int emode); static XLogRecord *ReadCheckpointRecord(XLogRecPtr RecPtr, int whichChkpt); static List *readTimeLineHistory(TimeLineID targetTLI); static bool existsTimeLineHistory(TimeLineID probeTLI); static bool rescanLatestTimeLine(void); static TimeLineID findNewestTimeLine(TimeLineID startTLI); static void writeTimeLineHistory(TimeLineID newTLI, TimeLineID parentTLI, TimeLineID endTLI, uint32 endLogId, uint32 endLogSeg); static void WriteControlFile(void); static void ReadControlFile(void); static char *str_time(pg_time_t tnow); static bool CheckForStandbyTrigger(void); #ifdef WAL_DEBUG static void xlog_outrec(StringInfo buf, XLogRecord *record); #endif static void pg_start_backup_callback(int code, Datum arg); static bool read_backup_label(XLogRecPtr *checkPointLoc, bool *backupEndRequired, bool *backupFromStandby); static void rm_redo_error_callback(void *arg); static int get_sync_bit(int method); /* * Insert an XLOG record having the specified RMID and info bytes, * with the body of the record being the data chunk(s) described by * the rdata chain (see xlog.h for notes about rdata). * * Returns XLOG pointer to end of record (beginning of next record). * This can be used as LSN for data pages affected by the logged action. * (LSN is the XLOG point up to which the XLOG must be flushed to disk * before the data page can be written out. This implements the basic * WAL rule "write the log before the data".) * * NB: this routine feels free to scribble on the XLogRecData structs, * though not on the data they reference. This is OK since the XLogRecData * structs are always just temporaries in the calling code. */ XLogRecPtr XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata) { XLogCtlInsert *Insert = &XLogCtl->Insert; XLogRecord *record; XLogContRecord *contrecord; XLogRecPtr RecPtr; XLogRecPtr WriteRqst; uint32 freespace; int curridx; XLogRecData *rdt; XLogRecData *rdt_lastnormal; Buffer dtbuf[XLR_MAX_BKP_BLOCKS]; bool dtbuf_bkp[XLR_MAX_BKP_BLOCKS]; BkpBlock dtbuf_xlg[XLR_MAX_BKP_BLOCKS]; XLogRecPtr dtbuf_lsn[XLR_MAX_BKP_BLOCKS]; XLogRecData dtbuf_rdt1[XLR_MAX_BKP_BLOCKS]; XLogRecData dtbuf_rdt2[XLR_MAX_BKP_BLOCKS]; XLogRecData dtbuf_rdt3[XLR_MAX_BKP_BLOCKS]; pg_crc32 rdata_crc; uint32 len, write_len; unsigned i; bool updrqst; bool doPageWrites; bool isLogSwitch = (rmid == RM_XLOG_ID && info == XLOG_SWITCH); uint8 info_orig = info; /* cross-check on whether we should be here or not */ if (!XLogInsertAllowed()) elog(ERROR, "cannot make new WAL entries during recovery"); /* info's high bits are reserved for use by me */ if (info & XLR_INFO_MASK) elog(PANIC, "invalid xlog info mask %02X", info); TRACE_POSTGRESQL_XLOG_INSERT(rmid, info); /* * In bootstrap mode, we don't actually log anything but XLOG resources; * return a phony record pointer. */ if (IsBootstrapProcessingMode() && rmid != RM_XLOG_ID) { RecPtr.xlogid = 0; RecPtr.xrecoff = SizeOfXLogLongPHD; /* start of 1st chkpt record */ return RecPtr; } /* * Here we scan the rdata chain, to determine which buffers must be backed * up. * * We may have to loop back to here if a race condition is detected below. * We could prevent the race by doing all this work while holding the * insert lock, but it seems better to avoid doing CRC calculations while * holding the lock. * * We add entries for backup blocks to the chain, so that they don't need * any special treatment in the critical section where the chunks are * copied into the WAL buffers. Those entries have to be unlinked from the * chain if we have to loop back here. */ begin:; for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++) { dtbuf[i] = InvalidBuffer; dtbuf_bkp[i] = false; } /* * Decide if we need to do full-page writes in this XLOG record: true if * full_page_writes is on or we have a PITR request for it. Since we * don't yet have the insert lock, fullPageWrites and forcePageWrites * could change under us, but we'll recheck them once we have the lock. */ doPageWrites = Insert->fullPageWrites || Insert->forcePageWrites; len = 0; for (rdt = rdata;;) { if (rdt->buffer == InvalidBuffer) { /* Simple data, just include it */ len += rdt->len; } else { /* Find info for buffer */ for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++) { if (rdt->buffer == dtbuf[i]) { /* Buffer already referenced by earlier chain item */ if (dtbuf_bkp[i]) { rdt->data = NULL; rdt->len = 0; } else if (rdt->data) len += rdt->len; break; } if (dtbuf[i] == InvalidBuffer) { /* OK, put it in this slot */ dtbuf[i] = rdt->buffer; if (XLogCheckBuffer(rdt, doPageWrites, &(dtbuf_lsn[i]), &(dtbuf_xlg[i]))) { dtbuf_bkp[i] = true; rdt->data = NULL; rdt->len = 0; } else if (rdt->data) len += rdt->len; break; } } if (i >= XLR_MAX_BKP_BLOCKS) elog(PANIC, "can backup at most %d blocks per xlog record", XLR_MAX_BKP_BLOCKS); } /* Break out of loop when rdt points to last chain item */ if (rdt->next == NULL) break; rdt = rdt->next; } /* * NOTE: We disallow len == 0 because it provides a useful bit of extra * error checking in ReadRecord. This means that all callers of * XLogInsert must supply at least some not-in-a-buffer data. However, we * make an exception for XLOG SWITCH records because we don't want them to * ever cross a segment boundary. */ if (len == 0 && !isLogSwitch) elog(PANIC, "invalid xlog record length %u", len); /* * Make additional rdata chain entries for the backup blocks, so that we * don't need to special-case them in the write loop. This modifies the * original rdata chain, but we keep a pointer to the last regular entry, * rdt_lastnormal, so that we can undo this if we have to loop back to the * beginning. * * At the exit of this loop, write_len includes the backup block data. * * Also set the appropriate info bits to show which buffers were backed * up. The i'th XLR_SET_BKP_BLOCK bit corresponds to the i'th distinct * buffer value (ignoring InvalidBuffer) appearing in the rdata chain. */ rdt_lastnormal = rdt; write_len = len; for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++) { BkpBlock *bkpb; char *page; if (!dtbuf_bkp[i]) continue; info |= XLR_SET_BKP_BLOCK(i); bkpb = &(dtbuf_xlg[i]); page = (char *) BufferGetBlock(dtbuf[i]); rdt->next = &(dtbuf_rdt1[i]); rdt = rdt->next; rdt->data = (char *) bkpb; rdt->len = sizeof(BkpBlock); write_len += sizeof(BkpBlock); rdt->next = &(dtbuf_rdt2[i]); rdt = rdt->next; if (bkpb->hole_length == 0) { rdt->data = page; rdt->len = BLCKSZ; write_len += BLCKSZ; rdt->next = NULL; } else { /* must skip the hole */ rdt->data = page; rdt->len = bkpb->hole_offset; write_len += bkpb->hole_offset; rdt->next = &(dtbuf_rdt3[i]); rdt = rdt->next; rdt->data = page + (bkpb->hole_offset + bkpb->hole_length); rdt->len = BLCKSZ - (bkpb->hole_offset + bkpb->hole_length); write_len += rdt->len; rdt->next = NULL; } } /* * Calculate CRC of the data, including all the backup blocks * * Note that the record header isn't added into the CRC initially since we * don't know the prev-link yet. Thus, the CRC will represent the CRC of * the whole record in the order: rdata, then backup blocks, then record * header. */ INIT_CRC32(rdata_crc); for (rdt = rdata; rdt != NULL; rdt = rdt->next) COMP_CRC32(rdata_crc, rdt->data, rdt->len); START_CRIT_SECTION(); /* Now wait to get insert lock */ LWLockAcquire(WALInsertLock, LW_EXCLUSIVE); /* * Check to see if my RedoRecPtr is out of date. If so, may have to go * back and recompute everything. This can only happen just after a * checkpoint, so it's better to be slow in this case and fast otherwise. * * If we aren't doing full-page writes then RedoRecPtr doesn't actually * affect the contents of the XLOG record, so we'll update our local copy * but not force a recomputation. */ if (!XLByteEQ(RedoRecPtr, Insert->RedoRecPtr)) { Assert(XLByteLT(RedoRecPtr, Insert->RedoRecPtr)); RedoRecPtr = Insert->RedoRecPtr; if (doPageWrites) { for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++) { if (dtbuf[i] == InvalidBuffer) continue; if (dtbuf_bkp[i] == false && XLByteLE(dtbuf_lsn[i], RedoRecPtr)) { /* * Oops, this buffer now needs to be backed up, but we * didn't think so above. Start over. */ LWLockRelease(WALInsertLock); END_CRIT_SECTION(); rdt_lastnormal->next = NULL; info = info_orig; goto begin; } } } } /* * Also check to see if fullPageWrites or forcePageWrites was just turned * on; if we weren't already doing full-page writes then go back and * recompute. (If it was just turned off, we could recompute the record * without full pages, but we choose not to bother.) */ if ((Insert->fullPageWrites || Insert->forcePageWrites) && !doPageWrites) { /* Oops, must redo it with full-page data. */ LWLockRelease(WALInsertLock); END_CRIT_SECTION(); rdt_lastnormal->next = NULL; info = info_orig; goto begin; } /* * If there isn't enough space on the current XLOG page for a record * header, advance to the next page (leaving the unused space as zeroes). */ updrqst = false; freespace = INSERT_FREESPACE(Insert); if (freespace < SizeOfXLogRecord) { updrqst = AdvanceXLInsertBuffer(false); freespace = INSERT_FREESPACE(Insert); } /* Compute record's XLOG location */ curridx = Insert->curridx; INSERT_RECPTR(RecPtr, Insert, curridx); /* * If the record is an XLOG_SWITCH, and we are exactly at the start of a * segment, we need not insert it (and don't want to because we'd like * consecutive switch requests to be no-ops). Instead, make sure * everything is written and flushed through the end of the prior segment, * and return the prior segment's end address. */ if (isLogSwitch && (RecPtr.xrecoff % XLogSegSize) == SizeOfXLogLongPHD) { /* We can release insert lock immediately */ LWLockRelease(WALInsertLock); RecPtr.xrecoff -= SizeOfXLogLongPHD; if (RecPtr.xrecoff == 0) { /* crossing a logid boundary */ RecPtr.xlogid -= 1; RecPtr.xrecoff = XLogFileSize; } LWLockAcquire(WALWriteLock, LW_EXCLUSIVE); LogwrtResult = XLogCtl->LogwrtResult; if (!XLByteLE(RecPtr, LogwrtResult.Flush)) { XLogwrtRqst FlushRqst; FlushRqst.Write = RecPtr; FlushRqst.Flush = RecPtr; XLogWrite(FlushRqst, false, false); } LWLockRelease(WALWriteLock); END_CRIT_SECTION(); return RecPtr; } /* Insert record header */ record = (XLogRecord *) Insert->currpos; record->xl_prev = Insert->PrevRecord; record->xl_xid = GetCurrentTransactionIdIfAny(); record->xl_tot_len = SizeOfXLogRecord + write_len; record->xl_len = len; /* doesn't include backup blocks */ record->xl_info = info; record->xl_rmid = rmid; /* Now we can finish computing the record's CRC */ COMP_CRC32(rdata_crc, (char *) record + sizeof(pg_crc32), SizeOfXLogRecord - sizeof(pg_crc32)); FIN_CRC32(rdata_crc); record->xl_crc = rdata_crc; #ifdef WAL_DEBUG if (XLOG_DEBUG) { StringInfoData buf; initStringInfo(&buf); appendStringInfo(&buf, "INSERT @ %X/%X: ", RecPtr.xlogid, RecPtr.xrecoff); xlog_outrec(&buf, record); if (rdata->data != NULL) { appendStringInfo(&buf, " - "); RmgrTable[record->xl_rmid].rm_desc(&buf, record->xl_info, rdata->data); } elog(LOG, "%s", buf.data); pfree(buf.data); } #endif /* Record begin of record in appropriate places */ ProcLastRecPtr = RecPtr; Insert->PrevRecord = RecPtr; Insert->currpos += SizeOfXLogRecord; freespace -= SizeOfXLogRecord; /* * Append the data, including backup blocks if any */ while (write_len) { while (rdata->data == NULL) rdata = rdata->next; if (freespace > 0) { if (rdata->len > freespace) { memcpy(Insert->currpos, rdata->data, freespace); rdata->data += freespace; rdata->len -= freespace; write_len -= freespace; } else { memcpy(Insert->currpos, rdata->data, rdata->len); freespace -= rdata->len; write_len -= rdata->len; Insert->currpos += rdata->len; rdata = rdata->next; continue; } } /* Use next buffer */ updrqst = AdvanceXLInsertBuffer(false); curridx = Insert->curridx; /* Insert cont-record header */ Insert->currpage->xlp_info |= XLP_FIRST_IS_CONTRECORD; contrecord = (XLogContRecord *) Insert->currpos; contrecord->xl_rem_len = write_len; Insert->currpos += SizeOfXLogContRecord; freespace = INSERT_FREESPACE(Insert); } /* Ensure next record will be properly aligned */ Insert->currpos = (char *) Insert->currpage + MAXALIGN(Insert->currpos - (char *) Insert->currpage); freespace = INSERT_FREESPACE(Insert); /* * The recptr I return is the beginning of the *next* record. This will be * stored as LSN for changed data pages... */ INSERT_RECPTR(RecPtr, Insert, curridx); /* * If the record is an XLOG_SWITCH, we must now write and flush all the * existing data, and then forcibly advance to the start of the next * segment. It's not good to do this I/O while holding the insert lock, * but there seems too much risk of confusion if we try to release the * lock sooner. Fortunately xlog switch needn't be a high-performance * operation anyway... */ if (isLogSwitch) { XLogwrtRqst FlushRqst; XLogRecPtr OldSegEnd; TRACE_POSTGRESQL_XLOG_SWITCH(); LWLockAcquire(WALWriteLock, LW_EXCLUSIVE); /* * Flush through the end of the page containing XLOG_SWITCH, and * perform end-of-segment actions (eg, notifying archiver). */ WriteRqst = XLogCtl->xlblocks[curridx]; FlushRqst.Write = WriteRqst; FlushRqst.Flush = WriteRqst; XLogWrite(FlushRqst, false, true); /* Set up the next buffer as first page of next segment */ /* Note: AdvanceXLInsertBuffer cannot need to do I/O here */ (void) AdvanceXLInsertBuffer(true); /* There should be no unwritten data */ curridx = Insert->curridx; Assert(curridx == XLogCtl->Write.curridx); /* Compute end address of old segment */ OldSegEnd = XLogCtl->xlblocks[curridx]; OldSegEnd.xrecoff -= XLOG_BLCKSZ; if (OldSegEnd.xrecoff == 0) { /* crossing a logid boundary */ OldSegEnd.xlogid -= 1; OldSegEnd.xrecoff = XLogFileSize; } /* Make it look like we've written and synced all of old segment */ LogwrtResult.Write = OldSegEnd; LogwrtResult.Flush = OldSegEnd; /* * Update shared-memory status --- this code should match XLogWrite */ { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); xlogctl->LogwrtResult = LogwrtResult; if (XLByteLT(xlogctl->LogwrtRqst.Write, LogwrtResult.Write)) xlogctl->LogwrtRqst.Write = LogwrtResult.Write; if (XLByteLT(xlogctl->LogwrtRqst.Flush, LogwrtResult.Flush)) xlogctl->LogwrtRqst.Flush = LogwrtResult.Flush; SpinLockRelease(&xlogctl->info_lck); } LWLockRelease(WALWriteLock); updrqst = false; /* done already */ } else { /* normal case, ie not xlog switch */ /* Need to update shared LogwrtRqst if some block was filled up */ if (freespace < SizeOfXLogRecord) { /* curridx is filled and available for writing out */ updrqst = true; } else { /* if updrqst already set, write through end of previous buf */ curridx = PrevBufIdx(curridx); } WriteRqst = XLogCtl->xlblocks[curridx]; } LWLockRelease(WALInsertLock); if (updrqst) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); /* advance global request to include new block(s) */ if (XLByteLT(xlogctl->LogwrtRqst.Write, WriteRqst)) xlogctl->LogwrtRqst.Write = WriteRqst; /* update local result copy while I have the chance */ LogwrtResult = xlogctl->LogwrtResult; SpinLockRelease(&xlogctl->info_lck); } XactLastRecEnd = RecPtr; END_CRIT_SECTION(); return RecPtr; } /* * Determine whether the buffer referenced by an XLogRecData item has to * be backed up, and if so fill a BkpBlock struct for it. In any case * save the buffer's LSN at *lsn. */ static bool XLogCheckBuffer(XLogRecData *rdata, bool doPageWrites, XLogRecPtr *lsn, BkpBlock *bkpb) { Page page; page = BufferGetPage(rdata->buffer); /* * XXX We assume page LSN is first data on *every* page that can be passed * to XLogInsert, whether it otherwise has the standard page layout or * not. */ *lsn = PageGetLSN(page); if (doPageWrites && XLByteLE(PageGetLSN(page), RedoRecPtr)) { /* * The page needs to be backed up, so set up *bkpb */ BufferGetTag(rdata->buffer, &bkpb->node, &bkpb->fork, &bkpb->block); if (rdata->buffer_std) { /* Assume we can omit data between pd_lower and pd_upper */ uint16 lower = ((PageHeader) page)->pd_lower; uint16 upper = ((PageHeader) page)->pd_upper; if (lower >= SizeOfPageHeaderData && upper > lower && upper <= BLCKSZ) { bkpb->hole_offset = lower; bkpb->hole_length = upper - lower; } else { /* No "hole" to compress out */ bkpb->hole_offset = 0; bkpb->hole_length = 0; } } else { /* Not a standard page header, don't try to eliminate "hole" */ bkpb->hole_offset = 0; bkpb->hole_length = 0; } return true; /* buffer requires backup */ } return false; /* buffer does not need to be backed up */ } /* * XLogArchiveNotify * * Create an archive notification file * * The name of the notification file is the message that will be picked up * by the archiver, e.g. we write 0000000100000001000000C6.ready * and the archiver then knows to archive XLOGDIR/0000000100000001000000C6, * then when complete, rename it to 0000000100000001000000C6.done */ static void XLogArchiveNotify(const char *xlog) { char archiveStatusPath[MAXPGPATH]; FILE *fd; /* insert an otherwise empty file called .ready */ StatusFilePath(archiveStatusPath, xlog, ".ready"); fd = AllocateFile(archiveStatusPath, "w"); if (fd == NULL) { ereport(LOG, (errcode_for_file_access(), errmsg("could not create archive status file \"%s\": %m", archiveStatusPath))); return; } if (FreeFile(fd)) { ereport(LOG, (errcode_for_file_access(), errmsg("could not write archive status file \"%s\": %m", archiveStatusPath))); return; } /* Notify archiver that it's got something to do */ if (IsUnderPostmaster) SendPostmasterSignal(PMSIGNAL_WAKEN_ARCHIVER); } /* * Convenience routine to notify using log/seg representation of filename */ static void XLogArchiveNotifySeg(uint32 log, uint32 seg) { char xlog[MAXFNAMELEN]; XLogFileName(xlog, ThisTimeLineID, log, seg); XLogArchiveNotify(xlog); } /* * XLogArchiveCheckDone * * This is called when we are ready to delete or recycle an old XLOG segment * file or backup history file. If it is okay to delete it then return true. * If it is not time to delete it, make sure a .ready file exists, and return * false. * * If .done exists, then return true; else if .ready exists, * then return false; else create .ready and return false. * * The reason we do things this way is so that if the original attempt to * create .ready fails, we'll retry during subsequent checkpoints. */ static bool XLogArchiveCheckDone(const char *xlog) { char archiveStatusPath[MAXPGPATH]; struct stat stat_buf; /* Always deletable if archiving is off */ if (!XLogArchivingActive()) return true; /* First check for .done --- this means archiver is done with it */ StatusFilePath(archiveStatusPath, xlog, ".done"); if (stat(archiveStatusPath, &stat_buf) == 0) return true; /* check for .ready --- this means archiver is still busy with it */ StatusFilePath(archiveStatusPath, xlog, ".ready"); if (stat(archiveStatusPath, &stat_buf) == 0) return false; /* Race condition --- maybe archiver just finished, so recheck */ StatusFilePath(archiveStatusPath, xlog, ".done"); if (stat(archiveStatusPath, &stat_buf) == 0) return true; /* Retry creation of the .ready file */ XLogArchiveNotify(xlog); return false; } /* * XLogArchiveIsBusy * * Check to see if an XLOG segment file is still unarchived. * This is almost but not quite the inverse of XLogArchiveCheckDone: in * the first place we aren't chartered to recreate the .ready file, and * in the second place we should consider that if the file is already gone * then it's not busy. (This check is needed to handle the race condition * that a checkpoint already deleted the no-longer-needed file.) */ static bool XLogArchiveIsBusy(const char *xlog) { char archiveStatusPath[MAXPGPATH]; struct stat stat_buf; /* First check for .done --- this means archiver is done with it */ StatusFilePath(archiveStatusPath, xlog, ".done"); if (stat(archiveStatusPath, &stat_buf) == 0) return false; /* check for .ready --- this means archiver is still busy with it */ StatusFilePath(archiveStatusPath, xlog, ".ready"); if (stat(archiveStatusPath, &stat_buf) == 0) return true; /* Race condition --- maybe archiver just finished, so recheck */ StatusFilePath(archiveStatusPath, xlog, ".done"); if (stat(archiveStatusPath, &stat_buf) == 0) return false; /* * Check to see if the WAL file has been removed by checkpoint, which * implies it has already been archived, and explains why we can't see a * status file for it. */ snprintf(archiveStatusPath, MAXPGPATH, XLOGDIR "/%s", xlog); if (stat(archiveStatusPath, &stat_buf) != 0 && errno == ENOENT) return false; return true; } /* * XLogArchiveCleanup * * Cleanup archive notification file(s) for a particular xlog segment */ static void XLogArchiveCleanup(const char *xlog) { char archiveStatusPath[MAXPGPATH]; /* Remove the .done file */ StatusFilePath(archiveStatusPath, xlog, ".done"); unlink(archiveStatusPath); /* should we complain about failure? */ /* Remove the .ready file if present --- normally it shouldn't be */ StatusFilePath(archiveStatusPath, xlog, ".ready"); unlink(archiveStatusPath); /* should we complain about failure? */ } /* * Advance the Insert state to the next buffer page, writing out the next * buffer if it still contains unwritten data. * * If new_segment is TRUE then we set up the next buffer page as the first * page of the next xlog segment file, possibly but not usually the next * consecutive file page. * * The global LogwrtRqst.Write pointer needs to be advanced to include the * just-filled page. If we can do this for free (without an extra lock), * we do so here. Otherwise the caller must do it. We return TRUE if the * request update still needs to be done, FALSE if we did it internally. * * Must be called with WALInsertLock held. */ static bool AdvanceXLInsertBuffer(bool new_segment) { XLogCtlInsert *Insert = &XLogCtl->Insert; int nextidx = NextBufIdx(Insert->curridx); bool update_needed = true; XLogRecPtr OldPageRqstPtr; XLogwrtRqst WriteRqst; XLogRecPtr NewPageEndPtr; XLogPageHeader NewPage; /* * Get ending-offset of the buffer page we need to replace (this may be * zero if the buffer hasn't been used yet). Fall through if it's already * written out. */ OldPageRqstPtr = XLogCtl->xlblocks[nextidx]; if (!XLByteLE(OldPageRqstPtr, LogwrtResult.Write)) { /* nope, got work to do... */ XLogRecPtr FinishedPageRqstPtr; FinishedPageRqstPtr = XLogCtl->xlblocks[Insert->curridx]; /* Before waiting, get info_lck and update LogwrtResult */ { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); if (XLByteLT(xlogctl->LogwrtRqst.Write, FinishedPageRqstPtr)) xlogctl->LogwrtRqst.Write = FinishedPageRqstPtr; LogwrtResult = xlogctl->LogwrtResult; SpinLockRelease(&xlogctl->info_lck); } update_needed = false; /* Did the shared-request update */ /* * Now that we have an up-to-date LogwrtResult value, see if we still * need to write it or if someone else already did. */ if (!XLByteLE(OldPageRqstPtr, LogwrtResult.Write)) { /* Must acquire write lock */ LWLockAcquire(WALWriteLock, LW_EXCLUSIVE); LogwrtResult = XLogCtl->LogwrtResult; if (XLByteLE(OldPageRqstPtr, LogwrtResult.Write)) { /* OK, someone wrote it already */ LWLockRelease(WALWriteLock); } else { /* * Have to write buffers while holding insert lock. This is * not good, so only write as much as we absolutely must. */ TRACE_POSTGRESQL_WAL_BUFFER_WRITE_DIRTY_START(); WriteRqst.Write = OldPageRqstPtr; WriteRqst.Flush.xlogid = 0; WriteRqst.Flush.xrecoff = 0; XLogWrite(WriteRqst, false, false); LWLockRelease(WALWriteLock); TRACE_POSTGRESQL_WAL_BUFFER_WRITE_DIRTY_DONE(); } } } /* * Now the next buffer slot is free and we can set it up to be the next * output page. */ NewPageEndPtr = XLogCtl->xlblocks[Insert->curridx]; if (new_segment) { /* force it to a segment start point */ NewPageEndPtr.xrecoff += XLogSegSize - 1; NewPageEndPtr.xrecoff -= NewPageEndPtr.xrecoff % XLogSegSize; } if (NewPageEndPtr.xrecoff >= XLogFileSize) { /* crossing a logid boundary */ NewPageEndPtr.xlogid += 1; NewPageEndPtr.xrecoff = XLOG_BLCKSZ; } else NewPageEndPtr.xrecoff += XLOG_BLCKSZ; XLogCtl->xlblocks[nextidx] = NewPageEndPtr; NewPage = (XLogPageHeader) (XLogCtl->pages + nextidx * (Size) XLOG_BLCKSZ); Insert->curridx = nextidx; Insert->currpage = NewPage; Insert->currpos = ((char *) NewPage) +SizeOfXLogShortPHD; /* * Be sure to re-zero the buffer so that bytes beyond what we've written * will look like zeroes and not valid XLOG records... */ MemSet((char *) NewPage, 0, XLOG_BLCKSZ); /* * Fill the new page's header */ NewPage ->xlp_magic = XLOG_PAGE_MAGIC; /* NewPage->xlp_info = 0; */ /* done by memset */ NewPage ->xlp_tli = ThisTimeLineID; NewPage ->xlp_pageaddr.xlogid = NewPageEndPtr.xlogid; NewPage ->xlp_pageaddr.xrecoff = NewPageEndPtr.xrecoff - XLOG_BLCKSZ; /* * If online backup is not in progress, mark the header to indicate that * WAL records beginning in this page have removable backup blocks. This * allows the WAL archiver to know whether it is safe to compress archived * WAL data by transforming full-block records into the non-full-block * format. It is sufficient to record this at the page level because we * force a page switch (in fact a segment switch) when starting a backup, * so the flag will be off before any records can be written during the * backup. At the end of a backup, the last page will be marked as all * unsafe when perhaps only part is unsafe, but at worst the archiver * would miss the opportunity to compress a few records. */ if (!Insert->forcePageWrites) NewPage ->xlp_info |= XLP_BKP_REMOVABLE; /* * If first page of an XLOG segment file, make it a long header. */ if ((NewPage->xlp_pageaddr.xrecoff % XLogSegSize) == 0) { XLogLongPageHeader NewLongPage = (XLogLongPageHeader) NewPage; NewLongPage->xlp_sysid = ControlFile->system_identifier; NewLongPage->xlp_seg_size = XLogSegSize; NewLongPage->xlp_xlog_blcksz = XLOG_BLCKSZ; NewPage ->xlp_info |= XLP_LONG_HEADER; Insert->currpos = ((char *) NewPage) +SizeOfXLogLongPHD; } return update_needed; } /* * Check whether we've consumed enough xlog space that a checkpoint is needed. * * logid/logseg indicate a log file that has just been filled up (or read * during recovery). We measure the distance from RedoRecPtr to logid/logseg * and see if that exceeds CheckPointSegments. * * Note: it is caller's responsibility that RedoRecPtr is up-to-date. */ static bool XLogCheckpointNeeded(uint32 logid, uint32 logseg) { /* * A straight computation of segment number could overflow 32 bits. Rather * than assuming we have working 64-bit arithmetic, we compare the * highest-order bits separately, and force a checkpoint immediately when * they change. */ uint32 old_segno, new_segno; uint32 old_highbits, new_highbits; old_segno = (RedoRecPtr.xlogid % XLogSegSize) * XLogSegsPerFile + (RedoRecPtr.xrecoff / XLogSegSize); old_highbits = RedoRecPtr.xlogid / XLogSegSize; new_segno = (logid % XLogSegSize) * XLogSegsPerFile + logseg; new_highbits = logid / XLogSegSize; if (new_highbits != old_highbits || new_segno >= old_segno + (uint32) (CheckPointSegments - 1)) return true; return false; } /* * Write and/or fsync the log at least as far as WriteRqst indicates. * * If flexible == TRUE, we don't have to write as far as WriteRqst, but * may stop at any convenient boundary (such as a cache or logfile boundary). * This option allows us to avoid uselessly issuing multiple writes when a * single one would do. * * If xlog_switch == TRUE, we are intending an xlog segment switch, so * perform end-of-segment actions after writing the last page, even if * it's not physically the end of its segment. (NB: this will work properly * only if caller specifies WriteRqst == page-end and flexible == false, * and there is some data to write.) * * Must be called with WALWriteLock held. */ static void XLogWrite(XLogwrtRqst WriteRqst, bool flexible, bool xlog_switch) { XLogCtlWrite *Write = &XLogCtl->Write; bool ispartialpage; bool last_iteration; bool finishing_seg; bool use_existent; int curridx; int npages; int startidx; uint32 startoffset; /* We should always be inside a critical section here */ Assert(CritSectionCount > 0); /* * Update local LogwrtResult (caller probably did this already, but...) */ LogwrtResult = XLogCtl->LogwrtResult; /* * Since successive pages in the xlog cache are consecutively allocated, * we can usually gather multiple pages together and issue just one * write() call. npages is the number of pages we have determined can be * written together; startidx is the cache block index of the first one, * and startoffset is the file offset at which it should go. The latter * two variables are only valid when npages > 0, but we must initialize * all of them to keep the compiler quiet. */ npages = 0; startidx = 0; startoffset = 0; /* * Within the loop, curridx is the cache block index of the page to * consider writing. We advance Write->curridx only after successfully * writing pages. (Right now, this refinement is useless since we are * going to PANIC if any error occurs anyway; but someday it may come in * useful.) */ curridx = Write->curridx; while (XLByteLT(LogwrtResult.Write, WriteRqst.Write)) { /* * Make sure we're not ahead of the insert process. This could happen * if we're passed a bogus WriteRqst.Write that is past the end of the * last page that's been initialized by AdvanceXLInsertBuffer. */ if (!XLByteLT(LogwrtResult.Write, XLogCtl->xlblocks[curridx])) elog(PANIC, "xlog write request %X/%X is past end of log %X/%X", LogwrtResult.Write.xlogid, LogwrtResult.Write.xrecoff, XLogCtl->xlblocks[curridx].xlogid, XLogCtl->xlblocks[curridx].xrecoff); /* Advance LogwrtResult.Write to end of current buffer page */ LogwrtResult.Write = XLogCtl->xlblocks[curridx]; ispartialpage = XLByteLT(WriteRqst.Write, LogwrtResult.Write); if (!XLByteInPrevSeg(LogwrtResult.Write, openLogId, openLogSeg)) { /* * Switch to new logfile segment. We cannot have any pending * pages here (since we dump what we have at segment end). */ Assert(npages == 0); if (openLogFile >= 0) XLogFileClose(); XLByteToPrevSeg(LogwrtResult.Write, openLogId, openLogSeg); /* create/use new log file */ use_existent = true; openLogFile = XLogFileInit(openLogId, openLogSeg, &use_existent, true); openLogOff = 0; } /* Make sure we have the current logfile open */ if (openLogFile < 0) { XLByteToPrevSeg(LogwrtResult.Write, openLogId, openLogSeg); openLogFile = XLogFileOpen(openLogId, openLogSeg); openLogOff = 0; } /* Add current page to the set of pending pages-to-dump */ if (npages == 0) { /* first of group */ startidx = curridx; startoffset = (LogwrtResult.Write.xrecoff - XLOG_BLCKSZ) % XLogSegSize; } npages++; /* * Dump the set if this will be the last loop iteration, or if we are * at the last page of the cache area (since the next page won't be * contiguous in memory), or if we are at the end of the logfile * segment. */ last_iteration = !XLByteLT(LogwrtResult.Write, WriteRqst.Write); finishing_seg = !ispartialpage && (startoffset + npages * XLOG_BLCKSZ) >= XLogSegSize; if (last_iteration || curridx == XLogCtl->XLogCacheBlck || finishing_seg) { char *from; Size nbytes; /* Need to seek in the file? */ if (openLogOff != startoffset) { if (lseek(openLogFile, (off_t) startoffset, SEEK_SET) < 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not seek in log file %u, " "segment %u to offset %u: %m", openLogId, openLogSeg, startoffset))); openLogOff = startoffset; } /* OK to write the page(s) */ from = XLogCtl->pages + startidx * (Size) XLOG_BLCKSZ; nbytes = npages * (Size) XLOG_BLCKSZ; errno = 0; if (write(openLogFile, from, nbytes) != nbytes) { /* if write didn't set errno, assume no disk space */ if (errno == 0) errno = ENOSPC; ereport(PANIC, (errcode_for_file_access(), errmsg("could not write to log file %u, segment %u " "at offset %u, length %lu: %m", openLogId, openLogSeg, openLogOff, (unsigned long) nbytes))); } /* Update state for write */ openLogOff += nbytes; Write->curridx = ispartialpage ? curridx : NextBufIdx(curridx); npages = 0; /* * If we just wrote the whole last page of a logfile segment, * fsync the segment immediately. This avoids having to go back * and re-open prior segments when an fsync request comes along * later. Doing it here ensures that one and only one backend will * perform this fsync. * * We also do this if this is the last page written for an xlog * switch. * * This is also the right place to notify the Archiver that the * segment is ready to copy to archival storage, and to update the * timer for archive_timeout, and to signal for a checkpoint if * too many logfile segments have been used since the last * checkpoint. */ if (finishing_seg || (xlog_switch && last_iteration)) { issue_xlog_fsync(openLogFile, openLogId, openLogSeg); LogwrtResult.Flush = LogwrtResult.Write; /* end of page */ if (XLogArchivingActive()) XLogArchiveNotifySeg(openLogId, openLogSeg); Write->lastSegSwitchTime = (pg_time_t) time(NULL); /* * Request a checkpoint if we've consumed too much xlog since * the last one. For speed, we first check using the local * copy of RedoRecPtr, which might be out of date; if it looks * like a checkpoint is needed, forcibly update RedoRecPtr and * recheck. */ if (IsUnderPostmaster && XLogCheckpointNeeded(openLogId, openLogSeg)) { (void) GetRedoRecPtr(); if (XLogCheckpointNeeded(openLogId, openLogSeg)) RequestCheckpoint(CHECKPOINT_CAUSE_XLOG); } } } if (ispartialpage) { /* Only asked to write a partial page */ LogwrtResult.Write = WriteRqst.Write; break; } curridx = NextBufIdx(curridx); /* If flexible, break out of loop as soon as we wrote something */ if (flexible && npages == 0) break; } Assert(npages == 0); Assert(curridx == Write->curridx); /* * If asked to flush, do so */ if (XLByteLT(LogwrtResult.Flush, WriteRqst.Flush) && XLByteLT(LogwrtResult.Flush, LogwrtResult.Write)) { /* * Could get here without iterating above loop, in which case we might * have no open file or the wrong one. However, we do not need to * fsync more than one file. */ if (sync_method != SYNC_METHOD_OPEN && sync_method != SYNC_METHOD_OPEN_DSYNC) { if (openLogFile >= 0 && !XLByteInPrevSeg(LogwrtResult.Write, openLogId, openLogSeg)) XLogFileClose(); if (openLogFile < 0) { XLByteToPrevSeg(LogwrtResult.Write, openLogId, openLogSeg); openLogFile = XLogFileOpen(openLogId, openLogSeg); openLogOff = 0; } issue_xlog_fsync(openLogFile, openLogId, openLogSeg); } LogwrtResult.Flush = LogwrtResult.Write; } /* * Update shared-memory status * * We make sure that the shared 'request' values do not fall behind the * 'result' values. This is not absolutely essential, but it saves some * code in a couple of places. */ { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); xlogctl->LogwrtResult = LogwrtResult; if (XLByteLT(xlogctl->LogwrtRqst.Write, LogwrtResult.Write)) xlogctl->LogwrtRqst.Write = LogwrtResult.Write; if (XLByteLT(xlogctl->LogwrtRqst.Flush, LogwrtResult.Flush)) xlogctl->LogwrtRqst.Flush = LogwrtResult.Flush; SpinLockRelease(&xlogctl->info_lck); } } /* * Record the LSN for an asynchronous transaction commit/abort * and nudge the WALWriter if there is work for it to do. * (This should not be called for synchronous commits.) */ void XLogSetAsyncXactLSN(XLogRecPtr asyncXactLSN) { XLogRecPtr WriteRqstPtr = asyncXactLSN; bool sleeping; /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); LogwrtResult = xlogctl->LogwrtResult; sleeping = xlogctl->WalWriterSleeping; if (XLByteLT(xlogctl->asyncXactLSN, asyncXactLSN)) xlogctl->asyncXactLSN = asyncXactLSN; SpinLockRelease(&xlogctl->info_lck); /* * If the WALWriter is sleeping, we should kick it to make it come out of * low-power mode. Otherwise, determine whether there's a full page of * WAL available to write. */ if (!sleeping) { /* back off to last completed page boundary */ WriteRqstPtr.xrecoff -= WriteRqstPtr.xrecoff % XLOG_BLCKSZ; /* if we have already flushed that far, we're done */ if (XLByteLE(WriteRqstPtr, LogwrtResult.Flush)) return; } /* * Nudge the WALWriter: it has a full page of WAL to write, or we want it * to come out of low-power mode so that this async commit will reach disk * within the expected amount of time. */ if (ProcGlobal->walwriterLatch) SetLatch(ProcGlobal->walwriterLatch); } /* * Advance minRecoveryPoint in control file. * * If we crash during recovery, we must reach this point again before the * database is consistent. * * If 'force' is true, 'lsn' argument is ignored. Otherwise, minRecoveryPoint * is only updated if it's not already greater than or equal to 'lsn'. */ static void UpdateMinRecoveryPoint(XLogRecPtr lsn, bool force) { /* Quick check using our local copy of the variable */ if (!updateMinRecoveryPoint || (!force && XLByteLE(lsn, minRecoveryPoint))) return; LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); /* update local copy */ minRecoveryPoint = ControlFile->minRecoveryPoint; /* * An invalid minRecoveryPoint means that we need to recover all the WAL, * i.e., we're doing crash recovery. We never modify the control file's * value in that case, so we can short-circuit future checks here too. */ if (minRecoveryPoint.xlogid == 0 && minRecoveryPoint.xrecoff == 0) updateMinRecoveryPoint = false; else if (force || XLByteLT(minRecoveryPoint, lsn)) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; XLogRecPtr newMinRecoveryPoint; /* * To avoid having to update the control file too often, we update it * all the way to the last record being replayed, even though 'lsn' * would suffice for correctness. This also allows the 'force' case * to not need a valid 'lsn' value. * * Another important reason for doing it this way is that the passed * 'lsn' value could be bogus, i.e., past the end of available WAL, if * the caller got it from a corrupted heap page. Accepting such a * value as the min recovery point would prevent us from coming up at * all. Instead, we just log a warning and continue with recovery. * (See also the comments about corrupt LSNs in XLogFlush.) */ SpinLockAcquire(&xlogctl->info_lck); newMinRecoveryPoint = xlogctl->replayEndRecPtr; SpinLockRelease(&xlogctl->info_lck); if (!force && XLByteLT(newMinRecoveryPoint, lsn)) elog(WARNING, "xlog min recovery request %X/%X is past current point %X/%X", lsn.xlogid, lsn.xrecoff, newMinRecoveryPoint.xlogid, newMinRecoveryPoint.xrecoff); /* update control file */ if (XLByteLT(ControlFile->minRecoveryPoint, newMinRecoveryPoint)) { ControlFile->minRecoveryPoint = newMinRecoveryPoint; UpdateControlFile(); minRecoveryPoint = newMinRecoveryPoint; ereport(DEBUG2, (errmsg("updated min recovery point to %X/%X", minRecoveryPoint.xlogid, minRecoveryPoint.xrecoff))); } } LWLockRelease(ControlFileLock); } /* * Ensure that all XLOG data through the given position is flushed to disk. * * NOTE: this differs from XLogWrite mainly in that the WALWriteLock is not * already held, and we try to avoid acquiring it if possible. */ void XLogFlush(XLogRecPtr record) { XLogRecPtr WriteRqstPtr; XLogwrtRqst WriteRqst; /* * During REDO, we are reading not writing WAL. Therefore, instead of * trying to flush the WAL, we should update minRecoveryPoint instead. We * test XLogInsertAllowed(), not InRecovery, because we need checkpointer * to act this way too, and because when it tries to write the * end-of-recovery checkpoint, it should indeed flush. */ if (!XLogInsertAllowed()) { UpdateMinRecoveryPoint(record, false); return; } /* Quick exit if already known flushed */ if (XLByteLE(record, LogwrtResult.Flush)) return; #ifdef WAL_DEBUG if (XLOG_DEBUG) elog(LOG, "xlog flush request %X/%X; write %X/%X; flush %X/%X", record.xlogid, record.xrecoff, LogwrtResult.Write.xlogid, LogwrtResult.Write.xrecoff, LogwrtResult.Flush.xlogid, LogwrtResult.Flush.xrecoff); #endif START_CRIT_SECTION(); /* * Since fsync is usually a horribly expensive operation, we try to * piggyback as much data as we can on each fsync: if we see any more data * entered into the xlog buffer, we'll write and fsync that too, so that * the final value of LogwrtResult.Flush is as large as possible. This * gives us some chance of avoiding another fsync immediately after. */ /* initialize to given target; may increase below */ WriteRqstPtr = record; /* * Now wait until we get the write lock, or someone else does the flush * for us. */ for (;;) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; /* read LogwrtResult and update local state */ SpinLockAcquire(&xlogctl->info_lck); if (XLByteLT(WriteRqstPtr, xlogctl->LogwrtRqst.Write)) WriteRqstPtr = xlogctl->LogwrtRqst.Write; LogwrtResult = xlogctl->LogwrtResult; SpinLockRelease(&xlogctl->info_lck); /* done already? */ if (XLByteLE(record, LogwrtResult.Flush)) break; /* * Try to get the write lock. If we can't get it immediately, wait * until it's released, and recheck if we still need to do the flush * or if the backend that held the lock did it for us already. This * helps to maintain a good rate of group committing when the system * is bottlenecked by the speed of fsyncing. */ if (!LWLockAcquireOrWait(WALWriteLock, LW_EXCLUSIVE)) { /* * The lock is now free, but we didn't acquire it yet. Before we * do, loop back to check if someone else flushed the record for * us already. */ continue; } /* Got the lock */ LogwrtResult = XLogCtl->LogwrtResult; if (!XLByteLE(record, LogwrtResult.Flush)) { /* try to write/flush later additions to XLOG as well */ if (LWLockConditionalAcquire(WALInsertLock, LW_EXCLUSIVE)) { XLogCtlInsert *Insert = &XLogCtl->Insert; uint32 freespace = INSERT_FREESPACE(Insert); if (freespace < SizeOfXLogRecord) /* buffer is full */ WriteRqstPtr = XLogCtl->xlblocks[Insert->curridx]; else { WriteRqstPtr = XLogCtl->xlblocks[Insert->curridx]; WriteRqstPtr.xrecoff -= freespace; } LWLockRelease(WALInsertLock); WriteRqst.Write = WriteRqstPtr; WriteRqst.Flush = WriteRqstPtr; } else { WriteRqst.Write = WriteRqstPtr; WriteRqst.Flush = record; } XLogWrite(WriteRqst, false, false); } LWLockRelease(WALWriteLock); /* done */ break; } END_CRIT_SECTION(); /* * If we still haven't flushed to the request point then we have a * problem; most likely, the requested flush point is past end of XLOG. * This has been seen to occur when a disk page has a corrupted LSN. * * Formerly we treated this as a PANIC condition, but that hurts the * system's robustness rather than helping it: we do not want to take down * the whole system due to corruption on one data page. In particular, if * the bad page is encountered again during recovery then we would be * unable to restart the database at all! (This scenario actually * happened in the field several times with 7.1 releases.) As of 8.4, bad * LSNs encountered during recovery are UpdateMinRecoveryPoint's problem; * the only time we can reach here during recovery is while flushing the * end-of-recovery checkpoint record, and we don't expect that to have a * bad LSN. * * Note that for calls from xact.c, the ERROR will be promoted to PANIC * since xact.c calls this routine inside a critical section. However, * calls from bufmgr.c are not within critical sections and so we will not * force a restart for a bad LSN on a data page. */ if (XLByteLT(LogwrtResult.Flush, record)) elog(ERROR, "xlog flush request %X/%X is not satisfied --- flushed only to %X/%X", record.xlogid, record.xrecoff, LogwrtResult.Flush.xlogid, LogwrtResult.Flush.xrecoff); } /* * Flush xlog, but without specifying exactly where to flush to. * * We normally flush only completed blocks; but if there is nothing to do on * that basis, we check for unflushed async commits in the current incomplete * block, and flush through the latest one of those. Thus, if async commits * are not being used, we will flush complete blocks only. We can guarantee * that async commits reach disk after at most three cycles; normally only * one or two. (When flushing complete blocks, we allow XLogWrite to write * "flexibly", meaning it can stop at the end of the buffer ring; this makes a * difference only with very high load or long wal_writer_delay, but imposes * one extra cycle for the worst case for async commits.) * * This routine is invoked periodically by the background walwriter process. * * Returns TRUE if we flushed anything. */ bool XLogBackgroundFlush(void) { XLogRecPtr WriteRqstPtr; bool flexible = true; bool wrote_something = false; /* XLOG doesn't need flushing during recovery */ if (RecoveryInProgress()) return false; /* read LogwrtResult and update local state */ { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); LogwrtResult = xlogctl->LogwrtResult; WriteRqstPtr = xlogctl->LogwrtRqst.Write; SpinLockRelease(&xlogctl->info_lck); } /* back off to last completed page boundary */ WriteRqstPtr.xrecoff -= WriteRqstPtr.xrecoff % XLOG_BLCKSZ; /* if we have already flushed that far, consider async commit records */ if (XLByteLE(WriteRqstPtr, LogwrtResult.Flush)) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); WriteRqstPtr = xlogctl->asyncXactLSN; SpinLockRelease(&xlogctl->info_lck); flexible = false; /* ensure it all gets written */ } /* * If already known flushed, we're done. Just need to check if we are * holding an open file handle to a logfile that's no longer in use, * preventing the file from being deleted. */ if (XLByteLE(WriteRqstPtr, LogwrtResult.Flush)) { if (openLogFile >= 0) { if (!XLByteInPrevSeg(LogwrtResult.Write, openLogId, openLogSeg)) { XLogFileClose(); } } return false; } #ifdef WAL_DEBUG if (XLOG_DEBUG) elog(LOG, "xlog bg flush request %X/%X; write %X/%X; flush %X/%X", WriteRqstPtr.xlogid, WriteRqstPtr.xrecoff, LogwrtResult.Write.xlogid, LogwrtResult.Write.xrecoff, LogwrtResult.Flush.xlogid, LogwrtResult.Flush.xrecoff); #endif START_CRIT_SECTION(); /* now wait for the write lock */ LWLockAcquire(WALWriteLock, LW_EXCLUSIVE); LogwrtResult = XLogCtl->LogwrtResult; if (!XLByteLE(WriteRqstPtr, LogwrtResult.Flush)) { XLogwrtRqst WriteRqst; WriteRqst.Write = WriteRqstPtr; WriteRqst.Flush = WriteRqstPtr; XLogWrite(WriteRqst, flexible, false); wrote_something = true; } LWLockRelease(WALWriteLock); END_CRIT_SECTION(); /* * If we wrote something then we have something to send to standbys also, * otherwise the replication delay become around 7s with just async * commit. */ if (wrote_something) WalSndWakeup(); return wrote_something; } /* * Test whether XLOG data has been flushed up to (at least) the given position. * * Returns true if a flush is still needed. (It may be that someone else * is already in process of flushing that far, however.) */ bool XLogNeedsFlush(XLogRecPtr record) { /* * During recovery, we don't flush WAL but update minRecoveryPoint * instead. So "needs flush" is taken to mean whether minRecoveryPoint * would need to be updated. */ if (RecoveryInProgress()) { /* Quick exit if already known updated */ if (XLByteLE(record, minRecoveryPoint) || !updateMinRecoveryPoint) return false; /* * Update local copy of minRecoveryPoint. But if the lock is busy, * just return a conservative guess. */ if (!LWLockConditionalAcquire(ControlFileLock, LW_SHARED)) return true; minRecoveryPoint = ControlFile->minRecoveryPoint; LWLockRelease(ControlFileLock); /* * An invalid minRecoveryPoint means that we need to recover all the * WAL, i.e., we're doing crash recovery. We never modify the control * file's value in that case, so we can short-circuit future checks * here too. */ if (minRecoveryPoint.xlogid == 0 && minRecoveryPoint.xrecoff == 0) updateMinRecoveryPoint = false; /* check again */ if (XLByteLE(record, minRecoveryPoint) || !updateMinRecoveryPoint) return false; else return true; } /* Quick exit if already known flushed */ if (XLByteLE(record, LogwrtResult.Flush)) return false; /* read LogwrtResult and update local state */ { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); LogwrtResult = xlogctl->LogwrtResult; SpinLockRelease(&xlogctl->info_lck); } /* check again */ if (XLByteLE(record, LogwrtResult.Flush)) return false; return true; } /* * Create a new XLOG file segment, or open a pre-existing one. * * log, seg: identify segment to be created/opened. * * *use_existent: if TRUE, OK to use a pre-existing file (else, any * pre-existing file will be deleted). On return, TRUE if a pre-existing * file was used. * * use_lock: if TRUE, acquire ControlFileLock while moving file into * place. This should be TRUE except during bootstrap log creation. The * caller must *not* hold the lock at call. * * Returns FD of opened file. * * Note: errors here are ERROR not PANIC because we might or might not be * inside a critical section (eg, during checkpoint there is no reason to * take down the system on failure). They will promote to PANIC if we are * in a critical section. */ int XLogFileInit(uint32 log, uint32 seg, bool *use_existent, bool use_lock) { char path[MAXPGPATH]; char tmppath[MAXPGPATH]; char *zbuffer; uint32 installed_log; uint32 installed_seg; int max_advance; int fd; int nbytes; XLogFilePath(path, ThisTimeLineID, log, seg); /* * Try to use existent file (checkpoint maker may have created it already) */ if (*use_existent) { fd = BasicOpenFile(path, O_RDWR | PG_BINARY | get_sync_bit(sync_method), S_IRUSR | S_IWUSR); if (fd < 0) { if (errno != ENOENT) ereport(ERROR, (errcode_for_file_access(), errmsg("could not open file \"%s\" (log file %u, segment %u): %m", path, log, seg))); } else return fd; } /* * Initialize an empty (all zeroes) segment. NOTE: it is possible that * another process is doing the same thing. If so, we will end up * pre-creating an extra log segment. That seems OK, and better than * holding the lock throughout this lengthy process. */ elog(DEBUG2, "creating and filling new WAL file"); snprintf(tmppath, MAXPGPATH, XLOGDIR "/xlogtemp.%d", (int) getpid()); unlink(tmppath); /* do not use get_sync_bit() here --- want to fsync only at end of fill */ fd = BasicOpenFile(tmppath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY, S_IRUSR | S_IWUSR); if (fd < 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not create file \"%s\": %m", tmppath))); /* * Zero-fill the file. We have to do this the hard way to ensure that all * the file space has really been allocated --- on platforms that allow * "holes" in files, just seeking to the end doesn't allocate intermediate * space. This way, we know that we have all the space and (after the * fsync below) that all the indirect blocks are down on disk. Therefore, * fdatasync(2) or O_DSYNC will be sufficient to sync future writes to the * log file. * * Note: palloc zbuffer, instead of just using a local char array, to * ensure it is reasonably well-aligned; this may save a few cycles * transferring data to the kernel. */ zbuffer = (char *) palloc0(XLOG_BLCKSZ); for (nbytes = 0; nbytes < XLogSegSize; nbytes += XLOG_BLCKSZ) { errno = 0; if ((int) write(fd, zbuffer, XLOG_BLCKSZ) != (int) XLOG_BLCKSZ) { int save_errno = errno; /* * If we fail to make the file, delete it to release disk space */ unlink(tmppath); /* if write didn't set errno, assume problem is no disk space */ errno = save_errno ? save_errno : ENOSPC; ereport(ERROR, (errcode_for_file_access(), errmsg("could not write to file \"%s\": %m", tmppath))); } } pfree(zbuffer); if (pg_fsync(fd) != 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not fsync file \"%s\": %m", tmppath))); if (close(fd)) ereport(ERROR, (errcode_for_file_access(), errmsg("could not close file \"%s\": %m", tmppath))); /* * Now move the segment into place with its final name. * * If caller didn't want to use a pre-existing file, get rid of any * pre-existing file. Otherwise, cope with possibility that someone else * has created the file while we were filling ours: if so, use ours to * pre-create a future log segment. */ installed_log = log; installed_seg = seg; max_advance = XLOGfileslop; if (!InstallXLogFileSegment(&installed_log, &installed_seg, tmppath, *use_existent, &max_advance, use_lock)) { /* * No need for any more future segments, or InstallXLogFileSegment() * failed to rename the file into place. If the rename failed, opening * the file below will fail. */ unlink(tmppath); } /* Set flag to tell caller there was no existent file */ *use_existent = false; /* Now open original target segment (might not be file I just made) */ fd = BasicOpenFile(path, O_RDWR | PG_BINARY | get_sync_bit(sync_method), S_IRUSR | S_IWUSR); if (fd < 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not open file \"%s\" (log file %u, segment %u): %m", path, log, seg))); elog(DEBUG2, "done creating and filling new WAL file"); return fd; } /* * Create a new XLOG file segment by copying a pre-existing one. * * log, seg: identify segment to be created. * * srcTLI, srclog, srcseg: identify segment to be copied (could be from * a different timeline) * * Currently this is only used during recovery, and so there are no locking * considerations. But we should be just as tense as XLogFileInit to avoid * emplacing a bogus file. */ static void XLogFileCopy(uint32 log, uint32 seg, TimeLineID srcTLI, uint32 srclog, uint32 srcseg) { char path[MAXPGPATH]; char tmppath[MAXPGPATH]; char buffer[XLOG_BLCKSZ]; int srcfd; int fd; int nbytes; /* * Open the source file */ XLogFilePath(path, srcTLI, srclog, srcseg); srcfd = BasicOpenFile(path, O_RDONLY | PG_BINARY, 0); if (srcfd < 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not open file \"%s\": %m", path))); /* * Copy into a temp file name. */ snprintf(tmppath, MAXPGPATH, XLOGDIR "/xlogtemp.%d", (int) getpid()); unlink(tmppath); /* do not use get_sync_bit() here --- want to fsync only at end of fill */ fd = BasicOpenFile(tmppath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY, S_IRUSR | S_IWUSR); if (fd < 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not create file \"%s\": %m", tmppath))); /* * Do the data copying. */ for (nbytes = 0; nbytes < XLogSegSize; nbytes += sizeof(buffer)) { errno = 0; if ((int) read(srcfd, buffer, sizeof(buffer)) != (int) sizeof(buffer)) { if (errno != 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not read file \"%s\": %m", path))); else ereport(ERROR, (errmsg("not enough data in file \"%s\"", path))); } errno = 0; if ((int) write(fd, buffer, sizeof(buffer)) != (int) sizeof(buffer)) { int save_errno = errno; /* * If we fail to make the file, delete it to release disk space */ unlink(tmppath); /* if write didn't set errno, assume problem is no disk space */ errno = save_errno ? save_errno : ENOSPC; ereport(ERROR, (errcode_for_file_access(), errmsg("could not write to file \"%s\": %m", tmppath))); } } if (pg_fsync(fd) != 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not fsync file \"%s\": %m", tmppath))); if (close(fd)) ereport(ERROR, (errcode_for_file_access(), errmsg("could not close file \"%s\": %m", tmppath))); close(srcfd); /* * Now move the segment into place with its final name. */ if (!InstallXLogFileSegment(&log, &seg, tmppath, false, NULL, false)) elog(ERROR, "InstallXLogFileSegment should not have failed"); } /* * Install a new XLOG segment file as a current or future log segment. * * This is used both to install a newly-created segment (which has a temp * filename while it's being created) and to recycle an old segment. * * *log, *seg: identify segment to install as (or first possible target). * When find_free is TRUE, these are modified on return to indicate the * actual installation location or last segment searched. * * tmppath: initial name of file to install. It will be renamed into place. * * find_free: if TRUE, install the new segment at the first empty log/seg * number at or after the passed numbers. If FALSE, install the new segment * exactly where specified, deleting any existing segment file there. * * *max_advance: maximum number of log/seg slots to advance past the starting * point. Fail if no free slot is found in this range. On return, reduced * by the number of slots skipped over. (Irrelevant, and may be NULL, * when find_free is FALSE.) * * use_lock: if TRUE, acquire ControlFileLock while moving file into * place. This should be TRUE except during bootstrap log creation. The * caller must *not* hold the lock at call. * * Returns TRUE if the file was installed successfully. FALSE indicates that * max_advance limit was exceeded, or an error occurred while renaming the * file into place. */ static bool InstallXLogFileSegment(uint32 *log, uint32 *seg, char *tmppath, bool find_free, int *max_advance, bool use_lock) { char path[MAXPGPATH]; struct stat stat_buf; XLogFilePath(path, ThisTimeLineID, *log, *seg); /* * We want to be sure that only one process does this at a time. */ if (use_lock) LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); if (!find_free) { /* Force installation: get rid of any pre-existing segment file */ unlink(path); } else { /* Find a free slot to put it in */ while (stat(path, &stat_buf) == 0) { if (*max_advance <= 0) { /* Failed to find a free slot within specified range */ if (use_lock) LWLockRelease(ControlFileLock); return false; } NextLogSeg(*log, *seg); (*max_advance)--; XLogFilePath(path, ThisTimeLineID, *log, *seg); } } /* * Prefer link() to rename() here just to be really sure that we don't * overwrite an existing logfile. However, there shouldn't be one, so * rename() is an acceptable substitute except for the truly paranoid. */ #if HAVE_WORKING_LINK if (link(tmppath, path) < 0) { if (use_lock) LWLockRelease(ControlFileLock); ereport(LOG, (errcode_for_file_access(), errmsg("could not link file \"%s\" to \"%s\" (initialization of log file %u, segment %u): %m", tmppath, path, *log, *seg))); return false; } unlink(tmppath); #else if (rename(tmppath, path) < 0) { if (use_lock) LWLockRelease(ControlFileLock); ereport(LOG, (errcode_for_file_access(), errmsg("could not rename file \"%s\" to \"%s\" (initialization of log file %u, segment %u): %m", tmppath, path, *log, *seg))); return false; } #endif if (use_lock) LWLockRelease(ControlFileLock); return true; } /* * Open a pre-existing logfile segment for writing. */ int XLogFileOpen(uint32 log, uint32 seg) { char path[MAXPGPATH]; int fd; XLogFilePath(path, ThisTimeLineID, log, seg); fd = BasicOpenFile(path, O_RDWR | PG_BINARY | get_sync_bit(sync_method), S_IRUSR | S_IWUSR); if (fd < 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not open file \"%s\" (log file %u, segment %u): %m", path, log, seg))); return fd; } /* * Open a logfile segment for reading (during recovery). * * If source = XLOG_FROM_ARCHIVE, the segment is retrieved from archive. * Otherwise, it's assumed to be already available in pg_xlog. */ static int XLogFileRead(uint32 log, uint32 seg, int emode, TimeLineID tli, int source, bool notfoundOk) { char xlogfname[MAXFNAMELEN]; char activitymsg[MAXFNAMELEN + 16]; char path[MAXPGPATH]; int fd; XLogFileName(xlogfname, tli, log, seg); switch (source) { case XLOG_FROM_ARCHIVE: /* Report recovery progress in PS display */ snprintf(activitymsg, sizeof(activitymsg), "waiting for %s", xlogfname); set_ps_display(activitymsg, false); restoredFromArchive = RestoreArchivedFile(path, xlogfname, "RECOVERYXLOG", XLogSegSize); if (!restoredFromArchive) return -1; break; case XLOG_FROM_PG_XLOG: case XLOG_FROM_STREAM: XLogFilePath(path, tli, log, seg); restoredFromArchive = false; break; default: elog(ERROR, "invalid XLogFileRead source %d", source); } /* * If the segment was fetched from archival storage, replace the existing * xlog segment (if any) with the archival version. */ if (source == XLOG_FROM_ARCHIVE) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; XLogRecPtr endptr; char xlogfpath[MAXPGPATH]; bool reload = false; struct stat statbuf; XLogFilePath(xlogfpath, tli, log, seg); if (stat(xlogfpath, &statbuf) == 0) { if (unlink(xlogfpath) != 0) ereport(FATAL, (errcode_for_file_access(), errmsg("could not remove file \"%s\": %m", xlogfpath))); reload = true; } if (rename(path, xlogfpath) < 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not rename file \"%s\" to \"%s\": %m", path, xlogfpath))); /* * If the existing segment was replaced, since walsenders might have * it open, request them to reload a currently-open segment. */ if (reload) WalSndRqstFileReload(); /* * Calculate the end location of the restored WAL file and save it in * shmem. It's used as current standby flush position, and cascading * walsenders try to send WAL records up to this location. */ endptr.xlogid = log; endptr.xrecoff = seg * XLogSegSize; XLByteAdvance(endptr, XLogSegSize); SpinLockAcquire(&xlogctl->info_lck); xlogctl->restoreLastRecPtr = endptr; SpinLockRelease(&xlogctl->info_lck); /* Signal walsender that new WAL has arrived */ if (AllowCascadeReplication()) WalSndWakeup(); } fd = BasicOpenFile(path, O_RDONLY | PG_BINARY, 0); if (fd >= 0) { /* Success! */ curFileTLI = tli; /* Report recovery progress in PS display */ snprintf(activitymsg, sizeof(activitymsg), "recovering %s", xlogfname); set_ps_display(activitymsg, false); /* Track source of data in assorted state variables */ readSource = source; XLogReceiptSource = source; /* In FROM_STREAM case, caller tracks receipt time, not me */ if (source != XLOG_FROM_STREAM) XLogReceiptTime = GetCurrentTimestamp(); return fd; } if (errno != ENOENT || !notfoundOk) /* unexpected failure? */ ereport(PANIC, (errcode_for_file_access(), errmsg("could not open file \"%s\" (log file %u, segment %u): %m", path, log, seg))); return -1; } /* * Open a logfile segment for reading (during recovery). * * This version searches for the segment with any TLI listed in expectedTLIs. */ static int XLogFileReadAnyTLI(uint32 log, uint32 seg, int emode, int sources) { char path[MAXPGPATH]; ListCell *cell; int fd; /* * Loop looking for a suitable timeline ID: we might need to read any of * the timelines listed in expectedTLIs. * * We expect curFileTLI on entry to be the TLI of the preceding file in * sequence, or 0 if there was no predecessor. We do not allow curFileTLI * to go backwards; this prevents us from picking up the wrong file when a * parent timeline extends to higher segment numbers than the child we * want to read. */ foreach(cell, expectedTLIs) { TimeLineID tli = (TimeLineID) lfirst_int(cell); if (tli < curFileTLI) break; /* don't bother looking at too-old TLIs */ if (sources & XLOG_FROM_ARCHIVE) { fd = XLogFileRead(log, seg, emode, tli, XLOG_FROM_ARCHIVE, true); if (fd != -1) { elog(DEBUG1, "got WAL segment from archive"); return fd; } } if (sources & XLOG_FROM_PG_XLOG) { fd = XLogFileRead(log, seg, emode, tli, XLOG_FROM_PG_XLOG, true); if (fd != -1) return fd; } } /* Couldn't find it. For simplicity, complain about front timeline */ XLogFilePath(path, recoveryTargetTLI, log, seg); errno = ENOENT; ereport(emode, (errcode_for_file_access(), errmsg("could not open file \"%s\" (log file %u, segment %u): %m", path, log, seg))); return -1; } /* * Close the current logfile segment for writing. */ static void XLogFileClose(void) { Assert(openLogFile >= 0); /* * WAL segment files will not be re-read in normal operation, so we advise * the OS to release any cached pages. But do not do so if WAL archiving * or streaming is active, because archiver and walsender process could * use the cache to read the WAL segment. */ #if defined(USE_POSIX_FADVISE) && defined(POSIX_FADV_DONTNEED) if (!XLogIsNeeded()) (void) posix_fadvise(openLogFile, 0, 0, POSIX_FADV_DONTNEED); #endif if (close(openLogFile)) ereport(PANIC, (errcode_for_file_access(), errmsg("could not close log file %u, segment %u: %m", openLogId, openLogSeg))); openLogFile = -1; } /* * Attempt to retrieve the specified file from off-line archival storage. * If successful, fill "path" with its complete path (note that this will be * a temp file name that doesn't follow the normal naming convention), and * return TRUE. * * If not successful, fill "path" with the name of the normal on-line file * (which may or may not actually exist, but we'll try to use it), and return * FALSE. * * For fixed-size files, the caller may pass the expected size as an * additional crosscheck on successful recovery. If the file size is not * known, set expectedSize = 0. */ static bool RestoreArchivedFile(char *path, const char *xlogfname, const char *recovername, off_t expectedSize) { char xlogpath[MAXPGPATH]; char xlogRestoreCmd[MAXPGPATH]; char lastRestartPointFname[MAXPGPATH]; char *dp; char *endp; const char *sp; int rc; bool signaled; struct stat stat_buf; uint32 restartLog; uint32 restartSeg; /* In standby mode, restore_command might not be supplied */ if (recoveryRestoreCommand == NULL) goto not_available; /* * When doing archive recovery, we always prefer an archived log file even * if a file of the same name exists in XLOGDIR. The reason is that the * file in XLOGDIR could be an old, un-filled or partly-filled version * that was copied and restored as part of backing up $PGDATA. * * We could try to optimize this slightly by checking the local copy * lastchange timestamp against the archived copy, but we have no API to * do this, nor can we guarantee that the lastchange timestamp was * preserved correctly when we copied to archive. Our aim is robustness, * so we elect not to do this. * * If we cannot obtain the log file from the archive, however, we will try * to use the XLOGDIR file if it exists. This is so that we can make use * of log segments that weren't yet transferred to the archive. * * Notice that we don't actually overwrite any files when we copy back * from archive because the recoveryRestoreCommand may inadvertently * restore inappropriate xlogs, or they may be corrupt, so we may wish to * fallback to the segments remaining in current XLOGDIR later. The * copy-from-archive filename is always the same, ensuring that we don't * run out of disk space on long recoveries. */ snprintf(xlogpath, MAXPGPATH, XLOGDIR "/%s", recovername); /* * Make sure there is no existing file named recovername. */ if (stat(xlogpath, &stat_buf) != 0) { if (errno != ENOENT) ereport(FATAL, (errcode_for_file_access(), errmsg("could not stat file \"%s\": %m", xlogpath))); } else { if (unlink(xlogpath) != 0) ereport(FATAL, (errcode_for_file_access(), errmsg("could not remove file \"%s\": %m", xlogpath))); } /* * Calculate the archive file cutoff point for use during log shipping * replication. All files earlier than this point can be deleted from the * archive, though there is no requirement to do so. * * We initialise this with the filename of an InvalidXLogRecPtr, which * will prevent the deletion of any WAL files from the archive because of * the alphabetic sorting property of WAL filenames. * * Once we have successfully located the redo pointer of the checkpoint * from which we start recovery we never request a file prior to the redo * pointer of the last restartpoint. When redo begins we know that we have * successfully located it, so there is no need for additional status * flags to signify the point when we can begin deleting WAL files from * the archive. */ if (InRedo) { XLByteToSeg(ControlFile->checkPointCopy.redo, restartLog, restartSeg); XLogFileName(lastRestartPointFname, ControlFile->checkPointCopy.ThisTimeLineID, restartLog, restartSeg); /* we shouldn't need anything earlier than last restart point */ Assert(strcmp(lastRestartPointFname, xlogfname) <= 0); } else XLogFileName(lastRestartPointFname, 0, 0, 0); /* * construct the command to be executed */ dp = xlogRestoreCmd; endp = xlogRestoreCmd + MAXPGPATH - 1; *endp = '\0'; for (sp = recoveryRestoreCommand; *sp; sp++) { if (*sp == '%') { switch (sp[1]) { case 'p': /* %p: relative path of target file */ sp++; StrNCpy(dp, xlogpath, endp - dp); make_native_path(dp); dp += strlen(dp); break; case 'f': /* %f: filename of desired file */ sp++; StrNCpy(dp, xlogfname, endp - dp); dp += strlen(dp); break; case 'r': /* %r: filename of last restartpoint */ sp++; StrNCpy(dp, lastRestartPointFname, endp - dp); dp += strlen(dp); break; case '%': /* convert %% to a single % */ sp++; if (dp < endp) *dp++ = *sp; break; default: /* otherwise treat the % as not special */ if (dp < endp) *dp++ = *sp; break; } } else { if (dp < endp) *dp++ = *sp; } } *dp = '\0'; ereport(DEBUG3, (errmsg_internal("executing restore command \"%s\"", xlogRestoreCmd))); /* * Check signals before restore command and reset afterwards. */ PreRestoreCommand(); /* * Copy xlog from archival storage to XLOGDIR */ rc = system(xlogRestoreCmd); PostRestoreCommand(); if (rc == 0) { /* * command apparently succeeded, but let's make sure the file is * really there now and has the correct size. */ if (stat(xlogpath, &stat_buf) == 0) { if (expectedSize > 0 && stat_buf.st_size != expectedSize) { int elevel; /* * If we find a partial file in standby mode, we assume it's * because it's just being copied to the archive, and keep * trying. * * Otherwise treat a wrong-sized file as FATAL to ensure the * DBA would notice it, but is that too strong? We could try * to plow ahead with a local copy of the file ... but the * problem is that there probably isn't one, and we'd * incorrectly conclude we've reached the end of WAL and we're * done recovering ... */ if (StandbyMode && stat_buf.st_size < expectedSize) elevel = DEBUG1; else elevel = FATAL; ereport(elevel, (errmsg("archive file \"%s\" has wrong size: %lu instead of %lu", xlogfname, (unsigned long) stat_buf.st_size, (unsigned long) expectedSize))); return false; } else { ereport(LOG, (errmsg("restored log file \"%s\" from archive", xlogfname))); strcpy(path, xlogpath); return true; } } else { /* stat failed */ if (errno != ENOENT) ereport(FATAL, (errcode_for_file_access(), errmsg("could not stat file \"%s\": %m", xlogpath))); } } /* * Remember, we rollforward UNTIL the restore fails so failure here is * just part of the process... that makes it difficult to determine * whether the restore failed because there isn't an archive to restore, * or because the administrator has specified the restore program * incorrectly. We have to assume the former. * * However, if the failure was due to any sort of signal, it's best to * punt and abort recovery. (If we "return false" here, upper levels will * assume that recovery is complete and start up the database!) It's * essential to abort on child SIGINT and SIGQUIT, because per spec * system() ignores SIGINT and SIGQUIT while waiting; if we see one of * those it's a good bet we should have gotten it too. * * On SIGTERM, assume we have received a fast shutdown request, and exit * cleanly. It's pure chance whether we receive the SIGTERM first, or the * child process. If we receive it first, the signal handler will call * proc_exit, otherwise we do it here. If we or the child process received * SIGTERM for any other reason than a fast shutdown request, postmaster * will perform an immediate shutdown when it sees us exiting * unexpectedly. * * Per the Single Unix Spec, shells report exit status > 128 when a called * command died on a signal. Also, 126 and 127 are used to report * problems such as an unfindable command; treat those as fatal errors * too. */ if (WIFSIGNALED(rc) && WTERMSIG(rc) == SIGTERM) proc_exit(1); signaled = WIFSIGNALED(rc) || WEXITSTATUS(rc) > 125; ereport(signaled ? FATAL : DEBUG2, (errmsg("could not restore file \"%s\" from archive: return code %d", xlogfname, rc))); not_available: /* * if an archived file is not available, there might still be a version of * this file in XLOGDIR, so return that as the filename to open. * * In many recovery scenarios we expect this to fail also, but if so that * just means we've reached the end of WAL. */ snprintf(path, MAXPGPATH, XLOGDIR "/%s", xlogfname); return false; } /* * Attempt to execute an external shell command during recovery. * * 'command' is the shell command to be executed, 'commandName' is a * human-readable name describing the command emitted in the logs. If * 'failOnSignal' is true and the command is killed by a signal, a FATAL * error is thrown. Otherwise a WARNING is emitted. * * This is currently used for recovery_end_command and archive_cleanup_command. */ static void ExecuteRecoveryCommand(char *command, char *commandName, bool failOnSignal) { char xlogRecoveryCmd[MAXPGPATH]; char lastRestartPointFname[MAXPGPATH]; char *dp; char *endp; const char *sp; int rc; bool signaled; uint32 restartLog; uint32 restartSeg; Assert(command && commandName); /* * Calculate the archive file cutoff point for use during log shipping * replication. All files earlier than this point can be deleted from the * archive, though there is no requirement to do so. */ LWLockAcquire(ControlFileLock, LW_SHARED); XLByteToSeg(ControlFile->checkPointCopy.redo, restartLog, restartSeg); XLogFileName(lastRestartPointFname, ControlFile->checkPointCopy.ThisTimeLineID, restartLog, restartSeg); LWLockRelease(ControlFileLock); /* * construct the command to be executed */ dp = xlogRecoveryCmd; endp = xlogRecoveryCmd + MAXPGPATH - 1; *endp = '\0'; for (sp = command; *sp; sp++) { if (*sp == '%') { switch (sp[1]) { case 'r': /* %r: filename of last restartpoint */ sp++; StrNCpy(dp, lastRestartPointFname, endp - dp); dp += strlen(dp); break; case '%': /* convert %% to a single % */ sp++; if (dp < endp) *dp++ = *sp; break; default: /* otherwise treat the % as not special */ if (dp < endp) *dp++ = *sp; break; } } else { if (dp < endp) *dp++ = *sp; } } *dp = '\0'; ereport(DEBUG3, (errmsg_internal("executing %s \"%s\"", commandName, command))); /* * execute the constructed command */ rc = system(xlogRecoveryCmd); if (rc != 0) { /* * If the failure was due to any sort of signal, it's best to punt and * abort recovery. See also detailed comments on signals in * RestoreArchivedFile(). */ signaled = WIFSIGNALED(rc) || WEXITSTATUS(rc) > 125; ereport((signaled && failOnSignal) ? FATAL : WARNING, /*------ translator: First %s represents a recovery.conf parameter name like "recovery_end_command", and the 2nd is the value of that parameter. */ (errmsg("%s \"%s\": return code %d", commandName, command, rc))); } } /* * Preallocate log files beyond the specified log endpoint. * * XXX this is currently extremely conservative, since it forces only one * future log segment to exist, and even that only if we are 75% done with * the current one. This is only appropriate for very low-WAL-volume systems. * High-volume systems will be OK once they've built up a sufficient set of * recycled log segments, but the startup transient is likely to include * a lot of segment creations by foreground processes, which is not so good. */ static void PreallocXlogFiles(XLogRecPtr endptr) { uint32 _logId; uint32 _logSeg; int lf; bool use_existent; XLByteToPrevSeg(endptr, _logId, _logSeg); if ((endptr.xrecoff - 1) % XLogSegSize >= (uint32) (0.75 * XLogSegSize)) { NextLogSeg(_logId, _logSeg); use_existent = true; lf = XLogFileInit(_logId, _logSeg, &use_existent, true); close(lf); if (!use_existent) CheckpointStats.ckpt_segs_added++; } } /* * Get the log/seg of the latest removed or recycled WAL segment. * Returns 0/0 if no WAL segments have been removed since startup. */ void XLogGetLastRemoved(uint32 *log, uint32 *seg) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); *log = xlogctl->lastRemovedLog; *seg = xlogctl->lastRemovedSeg; SpinLockRelease(&xlogctl->info_lck); } /* * Update the last removed log/seg pointer in shared memory, to reflect * that the given XLOG file has been removed. */ static void UpdateLastRemovedPtr(char *filename) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; uint32 tli, log, seg; XLogFromFileName(filename, &tli, &log, &seg); SpinLockAcquire(&xlogctl->info_lck); if (log > xlogctl->lastRemovedLog || (log == xlogctl->lastRemovedLog && seg > xlogctl->lastRemovedSeg)) { xlogctl->lastRemovedLog = log; xlogctl->lastRemovedSeg = seg; } SpinLockRelease(&xlogctl->info_lck); } /* * Recycle or remove all log files older or equal to passed log/seg# * * endptr is current (or recent) end of xlog; this is used to determine * whether we want to recycle rather than delete no-longer-wanted log files. */ static void RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr) { uint32 endlogId; uint32 endlogSeg; int max_advance; DIR *xldir; struct dirent *xlde; char lastoff[MAXFNAMELEN]; char path[MAXPGPATH]; #ifdef WIN32 char newpath[MAXPGPATH]; #endif struct stat statbuf; /* * Initialize info about where to try to recycle to. We allow recycling * segments up to XLOGfileslop segments beyond the current XLOG location. */ XLByteToPrevSeg(endptr, endlogId, endlogSeg); max_advance = XLOGfileslop; xldir = AllocateDir(XLOGDIR); if (xldir == NULL) ereport(ERROR, (errcode_for_file_access(), errmsg("could not open transaction log directory \"%s\": %m", XLOGDIR))); XLogFileName(lastoff, ThisTimeLineID, log, seg); elog(DEBUG2, "attempting to remove WAL segments older than log file %s", lastoff); while ((xlde = ReadDir(xldir, XLOGDIR)) != NULL) { /* * We ignore the timeline part of the XLOG segment identifiers in * deciding whether a segment is still needed. This ensures that we * won't prematurely remove a segment from a parent timeline. We could * probably be a little more proactive about removing segments of * non-parent timelines, but that would be a whole lot more * complicated. * * We use the alphanumeric sorting property of the filenames to decide * which ones are earlier than the lastoff segment. */ if (strlen(xlde->d_name) == 24 && strspn(xlde->d_name, "0123456789ABCDEF") == 24 && strcmp(xlde->d_name + 8, lastoff + 8) <= 0) { if (RecoveryInProgress() || XLogArchiveCheckDone(xlde->d_name)) { snprintf(path, MAXPGPATH, XLOGDIR "/%s", xlde->d_name); /* Update the last removed location in shared memory first */ UpdateLastRemovedPtr(xlde->d_name); /* * Before deleting the file, see if it can be recycled as a * future log segment. Only recycle normal files, pg_standby * for example can create symbolic links pointing to a * separate archive directory. */ if (lstat(path, &statbuf) == 0 && S_ISREG(statbuf.st_mode) && InstallXLogFileSegment(&endlogId, &endlogSeg, path, true, &max_advance, true)) { ereport(DEBUG2, (errmsg("recycled transaction log file \"%s\"", xlde->d_name))); CheckpointStats.ckpt_segs_recycled++; /* Needn't recheck that slot on future iterations */ if (max_advance > 0) { NextLogSeg(endlogId, endlogSeg); max_advance--; } } else { /* No need for any more future segments... */ int rc; ereport(DEBUG2, (errmsg("removing transaction log file \"%s\"", xlde->d_name))); #ifdef WIN32 /* * On Windows, if another process (e.g another backend) * holds the file open in FILE_SHARE_DELETE mode, unlink * will succeed, but the file will still show up in * directory listing until the last handle is closed. To * avoid confusing the lingering deleted file for a live * WAL file that needs to be archived, rename it before * deleting it. * * If another process holds the file open without * FILE_SHARE_DELETE flag, rename will fail. We'll try * again at the next checkpoint. */ snprintf(newpath, MAXPGPATH, "%s.deleted", path); if (rename(path, newpath) != 0) { ereport(LOG, (errcode_for_file_access(), errmsg("could not rename old transaction log file \"%s\": %m", path))); continue; } rc = unlink(newpath); #else rc = unlink(path); #endif if (rc != 0) { ereport(LOG, (errcode_for_file_access(), errmsg("could not remove old transaction log file \"%s\": %m", path))); continue; } CheckpointStats.ckpt_segs_removed++; } XLogArchiveCleanup(xlde->d_name); } } } FreeDir(xldir); } /* * Verify whether pg_xlog and pg_xlog/archive_status exist. * If the latter does not exist, recreate it. * * It is not the goal of this function to verify the contents of these * directories, but to help in cases where someone has performed a cluster * copy for PITR purposes but omitted pg_xlog from the copy. * * We could also recreate pg_xlog if it doesn't exist, but a deliberate * policy decision was made not to. It is fairly common for pg_xlog to be * a symlink, and if that was the DBA's intent then automatically making a * plain directory would result in degraded performance with no notice. */ static void ValidateXLOGDirectoryStructure(void) { char path[MAXPGPATH]; struct stat stat_buf; /* Check for pg_xlog; if it doesn't exist, error out */ if (stat(XLOGDIR, &stat_buf) != 0 || !S_ISDIR(stat_buf.st_mode)) ereport(FATAL, (errmsg("required WAL directory \"%s\" does not exist", XLOGDIR))); /* Check for archive_status */ snprintf(path, MAXPGPATH, XLOGDIR "/archive_status"); if (stat(path, &stat_buf) == 0) { /* Check for weird cases where it exists but isn't a directory */ if (!S_ISDIR(stat_buf.st_mode)) ereport(FATAL, (errmsg("required WAL directory \"%s\" does not exist", path))); } else { ereport(LOG, (errmsg("creating missing WAL directory \"%s\"", path))); if (mkdir(path, S_IRWXU) < 0) ereport(FATAL, (errmsg("could not create missing directory \"%s\": %m", path))); } } /* * Remove previous backup history files. This also retries creation of * .ready files for any backup history files for which XLogArchiveNotify * failed earlier. */ static void CleanupBackupHistory(void) { DIR *xldir; struct dirent *xlde; char path[MAXPGPATH]; xldir = AllocateDir(XLOGDIR); if (xldir == NULL) ereport(ERROR, (errcode_for_file_access(), errmsg("could not open transaction log directory \"%s\": %m", XLOGDIR))); while ((xlde = ReadDir(xldir, XLOGDIR)) != NULL) { if (strlen(xlde->d_name) > 24 && strspn(xlde->d_name, "0123456789ABCDEF") == 24 && strcmp(xlde->d_name + strlen(xlde->d_name) - strlen(".backup"), ".backup") == 0) { if (XLogArchiveCheckDone(xlde->d_name)) { ereport(DEBUG2, (errmsg("removing transaction log backup history file \"%s\"", xlde->d_name))); snprintf(path, MAXPGPATH, XLOGDIR "/%s", xlde->d_name); unlink(path); XLogArchiveCleanup(xlde->d_name); } } } FreeDir(xldir); } /* * Restore the backup blocks present in an XLOG record, if any. * * We assume all of the record has been read into memory at *record. * * Note: when a backup block is available in XLOG, we restore it * unconditionally, even if the page in the database appears newer. * This is to protect ourselves against database pages that were partially * or incorrectly written during a crash. We assume that the XLOG data * must be good because it has passed a CRC check, while the database * page might not be. This will force us to replay all subsequent * modifications of the page that appear in XLOG, rather than possibly * ignoring them as already applied, but that's not a huge drawback. * * If 'cleanup' is true, a cleanup lock is used when restoring blocks. * Otherwise, a normal exclusive lock is used. During crash recovery, that's * just pro forma because there can't be any regular backends in the system, * but in hot standby mode the distinction is important. The 'cleanup' * argument applies to all backup blocks in the WAL record, that suffices for * now. */ void RestoreBkpBlocks(XLogRecPtr lsn, XLogRecord *record, bool cleanup) { Buffer buffer; Page page; BkpBlock bkpb; char *blk; int i; if (!(record->xl_info & XLR_BKP_BLOCK_MASK)) return; blk = (char *) XLogRecGetData(record) + record->xl_len; for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++) { if (!(record->xl_info & XLR_SET_BKP_BLOCK(i))) continue; memcpy(&bkpb, blk, sizeof(BkpBlock)); blk += sizeof(BkpBlock); buffer = XLogReadBufferExtended(bkpb.node, bkpb.fork, bkpb.block, RBM_ZERO); Assert(BufferIsValid(buffer)); if (cleanup) LockBufferForCleanup(buffer); else LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE); page = (Page) BufferGetPage(buffer); if (bkpb.hole_length == 0) { memcpy((char *) page, blk, BLCKSZ); } else { memcpy((char *) page, blk, bkpb.hole_offset); /* must zero-fill the hole */ MemSet((char *) page + bkpb.hole_offset, 0, bkpb.hole_length); memcpy((char *) page + (bkpb.hole_offset + bkpb.hole_length), blk + bkpb.hole_offset, BLCKSZ - (bkpb.hole_offset + bkpb.hole_length)); } PageSetLSN(page, lsn); PageSetTLI(page, ThisTimeLineID); MarkBufferDirty(buffer); UnlockReleaseBuffer(buffer); blk += BLCKSZ - bkpb.hole_length; } } /* * CRC-check an XLOG record. We do not believe the contents of an XLOG * record (other than to the minimal extent of computing the amount of * data to read in) until we've checked the CRCs. * * We assume all of the record has been read into memory at *record. */ static bool RecordIsValid(XLogRecord *record, XLogRecPtr recptr, int emode) { pg_crc32 crc; int i; uint32 len = record->xl_len; BkpBlock bkpb; char *blk; /* First the rmgr data */ INIT_CRC32(crc); COMP_CRC32(crc, XLogRecGetData(record), len); /* Add in the backup blocks, if any */ blk = (char *) XLogRecGetData(record) + len; for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++) { uint32 blen; if (!(record->xl_info & XLR_SET_BKP_BLOCK(i))) continue; memcpy(&bkpb, blk, sizeof(BkpBlock)); if (bkpb.hole_offset + bkpb.hole_length > BLCKSZ) { ereport(emode_for_corrupt_record(emode, recptr), (errmsg("incorrect hole size in record at %X/%X", recptr.xlogid, recptr.xrecoff))); return false; } blen = sizeof(BkpBlock) + BLCKSZ - bkpb.hole_length; COMP_CRC32(crc, blk, blen); blk += blen; } /* Check that xl_tot_len agrees with our calculation */ if (blk != (char *) record + record->xl_tot_len) { ereport(emode_for_corrupt_record(emode, recptr), (errmsg("incorrect total length in record at %X/%X", recptr.xlogid, recptr.xrecoff))); return false; } /* Finally include the record header */ COMP_CRC32(crc, (char *) record + sizeof(pg_crc32), SizeOfXLogRecord - sizeof(pg_crc32)); FIN_CRC32(crc); if (!EQ_CRC32(record->xl_crc, crc)) { ereport(emode_for_corrupt_record(emode, recptr), (errmsg("incorrect resource manager data checksum in record at %X/%X", recptr.xlogid, recptr.xrecoff))); return false; } return true; } /* * Attempt to read an XLOG record. * * If RecPtr is not NULL, try to read a record at that position. Otherwise * try to read a record just after the last one previously read. * * If no valid record is available, returns NULL, or fails if emode is PANIC. * (emode must be either PANIC, LOG) * * The record is copied into readRecordBuf, so that on successful return, * the returned record pointer always points there. */ static XLogRecord * ReadRecord(XLogRecPtr *RecPtr, int emode, bool fetching_ckpt) { XLogRecord *record; char *buffer; XLogRecPtr tmpRecPtr = EndRecPtr; bool randAccess = false; uint32 len, total_len; uint32 targetRecOff; uint32 pageHeaderSize; if (readBuf == NULL) { /* * First time through, permanently allocate readBuf. We do it this * way, rather than just making a static array, for two reasons: (1) * no need to waste the storage in most instantiations of the backend; * (2) a static char array isn't guaranteed to have any particular * alignment, whereas malloc() will provide MAXALIGN'd storage. */ readBuf = (char *) malloc(XLOG_BLCKSZ); Assert(readBuf != NULL); } if (RecPtr == NULL) { RecPtr = &tmpRecPtr; /* * RecPtr is pointing to end+1 of the previous WAL record. We must * advance it if necessary to where the next record starts. First, * align to next page if no more records can fit on the current page. */ if (XLOG_BLCKSZ - (RecPtr->xrecoff % XLOG_BLCKSZ) < SizeOfXLogRecord) NextLogPage(*RecPtr); /* Check for crossing of xlog segment boundary */ if (RecPtr->xrecoff >= XLogFileSize) { (RecPtr->xlogid)++; RecPtr->xrecoff = 0; } /* * If at page start, we must skip over the page header. But we can't * do that until we've read in the page, since the header size is * variable. */ } else { /* * In this case, the passed-in record pointer should already be * pointing to a valid record starting position. */ if (!XRecOffIsValid(RecPtr->xrecoff)) ereport(PANIC, (errmsg("invalid record offset at %X/%X", RecPtr->xlogid, RecPtr->xrecoff))); /* * Since we are going to a random position in WAL, forget any prior * state about what timeline we were in, and allow it to be any * timeline in expectedTLIs. We also set a flag to allow curFileTLI * to go backwards (but we can't reset that variable right here, since * we might not change files at all). */ lastPageTLI = 0; /* see comment in ValidXLOGHeader */ randAccess = true; /* allow curFileTLI to go backwards too */ } /* This is the first try to read this page. */ failedSources = 0; retry: /* Read the page containing the record */ if (!XLogPageRead(RecPtr, emode, fetching_ckpt, randAccess)) return NULL; pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) readBuf); targetRecOff = RecPtr->xrecoff % XLOG_BLCKSZ; if (targetRecOff == 0) { /* * At page start, so skip over page header. The Assert checks that * we're not scribbling on caller's record pointer; it's OK because we * can only get here in the continuing-from-prev-record case, since * XRecOffIsValid rejected the zero-page-offset case otherwise. */ Assert(RecPtr == &tmpRecPtr); RecPtr->xrecoff += pageHeaderSize; targetRecOff = pageHeaderSize; } else if (targetRecOff < pageHeaderSize) { ereport(emode_for_corrupt_record(emode, *RecPtr), (errmsg("invalid record offset at %X/%X", RecPtr->xlogid, RecPtr->xrecoff))); goto next_record_is_invalid; } if ((((XLogPageHeader) readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD) && targetRecOff == pageHeaderSize) { ereport(emode_for_corrupt_record(emode, *RecPtr), (errmsg("contrecord is requested by %X/%X", RecPtr->xlogid, RecPtr->xrecoff))); goto next_record_is_invalid; } record = (XLogRecord *) ((char *) readBuf + RecPtr->xrecoff % XLOG_BLCKSZ); /* * xl_len == 0 is bad data for everything except XLOG SWITCH, where it is * required. */ if (record->xl_rmid == RM_XLOG_ID && record->xl_info == XLOG_SWITCH) { if (record->xl_len != 0) { ereport(emode_for_corrupt_record(emode, *RecPtr), (errmsg("invalid xlog switch record at %X/%X", RecPtr->xlogid, RecPtr->xrecoff))); goto next_record_is_invalid; } } else if (record->xl_len == 0) { ereport(emode_for_corrupt_record(emode, *RecPtr), (errmsg("record with zero length at %X/%X", RecPtr->xlogid, RecPtr->xrecoff))); goto next_record_is_invalid; } if (record->xl_tot_len < SizeOfXLogRecord + record->xl_len || record->xl_tot_len > SizeOfXLogRecord + record->xl_len + XLR_MAX_BKP_BLOCKS * (sizeof(BkpBlock) + BLCKSZ)) { ereport(emode_for_corrupt_record(emode, *RecPtr), (errmsg("invalid record length at %X/%X", RecPtr->xlogid, RecPtr->xrecoff))); goto next_record_is_invalid; } if (record->xl_rmid > RM_MAX_ID) { ereport(emode_for_corrupt_record(emode, *RecPtr), (errmsg("invalid resource manager ID %u at %X/%X", record->xl_rmid, RecPtr->xlogid, RecPtr->xrecoff))); goto next_record_is_invalid; } if (randAccess) { /* * We can't exactly verify the prev-link, but surely it should be less * than the record's own address. */ if (!XLByteLT(record->xl_prev, *RecPtr)) { ereport(emode_for_corrupt_record(emode, *RecPtr), (errmsg("record with incorrect prev-link %X/%X at %X/%X", record->xl_prev.xlogid, record->xl_prev.xrecoff, RecPtr->xlogid, RecPtr->xrecoff))); goto next_record_is_invalid; } } else { /* * Record's prev-link should exactly match our previous location. This * check guards against torn WAL pages where a stale but valid-looking * WAL record starts on a sector boundary. */ if (!XLByteEQ(record->xl_prev, ReadRecPtr)) { ereport(emode_for_corrupt_record(emode, *RecPtr), (errmsg("record with incorrect prev-link %X/%X at %X/%X", record->xl_prev.xlogid, record->xl_prev.xrecoff, RecPtr->xlogid, RecPtr->xrecoff))); goto next_record_is_invalid; } } /* * Allocate or enlarge readRecordBuf as needed. To avoid useless small * increases, round its size to a multiple of XLOG_BLCKSZ, and make sure * it's at least 4*Max(BLCKSZ, XLOG_BLCKSZ) to start with. (That is * enough for all "normal" records, but very large commit or abort records * might need more space.) */ total_len = record->xl_tot_len; if (total_len > readRecordBufSize) { uint32 newSize = total_len; newSize += XLOG_BLCKSZ - (newSize % XLOG_BLCKSZ); newSize = Max(newSize, 4 * Max(BLCKSZ, XLOG_BLCKSZ)); if (readRecordBuf) free(readRecordBuf); readRecordBuf = (char *) malloc(newSize); if (!readRecordBuf) { readRecordBufSize = 0; /* We treat this as a "bogus data" condition */ ereport(emode_for_corrupt_record(emode, *RecPtr), (errmsg("record length %u at %X/%X too long", total_len, RecPtr->xlogid, RecPtr->xrecoff))); goto next_record_is_invalid; } readRecordBufSize = newSize; } buffer = readRecordBuf; len = XLOG_BLCKSZ - RecPtr->xrecoff % XLOG_BLCKSZ; if (total_len > len) { /* Need to reassemble record */ XLogContRecord *contrecord; XLogRecPtr pagelsn; uint32 gotlen = len; /* Initialize pagelsn to the beginning of the page this record is on */ pagelsn = *RecPtr; pagelsn.xrecoff = (pagelsn.xrecoff / XLOG_BLCKSZ) * XLOG_BLCKSZ; memcpy(buffer, record, len); record = (XLogRecord *) buffer; buffer += len; for (;;) { /* Calculate pointer to beginning of next page */ pagelsn.xrecoff += XLOG_BLCKSZ; if (pagelsn.xrecoff >= XLogFileSize) { (pagelsn.xlogid)++; pagelsn.xrecoff = 0; } /* Wait for the next page to become available */ if (!XLogPageRead(&pagelsn, emode, false, false)) return NULL; /* Check that the continuation record looks valid */ if (!(((XLogPageHeader) readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD)) { ereport(emode_for_corrupt_record(emode, *RecPtr), (errmsg("there is no contrecord flag in log file %u, segment %u, offset %u", readId, readSeg, readOff))); goto next_record_is_invalid; } pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) readBuf); contrecord = (XLogContRecord *) ((char *) readBuf + pageHeaderSize); if (contrecord->xl_rem_len == 0 || total_len != (contrecord->xl_rem_len + gotlen)) { ereport(emode_for_corrupt_record(emode, *RecPtr), (errmsg("invalid contrecord length %u in log file %u, segment %u, offset %u", contrecord->xl_rem_len, readId, readSeg, readOff))); goto next_record_is_invalid; } len = XLOG_BLCKSZ - pageHeaderSize - SizeOfXLogContRecord; if (contrecord->xl_rem_len > len) { memcpy(buffer, (char *) contrecord + SizeOfXLogContRecord, len); gotlen += len; buffer += len; continue; } memcpy(buffer, (char *) contrecord + SizeOfXLogContRecord, contrecord->xl_rem_len); break; } if (!RecordIsValid(record, *RecPtr, emode)) goto next_record_is_invalid; pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) readBuf); EndRecPtr.xlogid = readId; EndRecPtr.xrecoff = readSeg * XLogSegSize + readOff + pageHeaderSize + MAXALIGN(SizeOfXLogContRecord + contrecord->xl_rem_len); ReadRecPtr = *RecPtr; /* needn't worry about XLOG SWITCH, it can't cross page boundaries */ return record; } /* Record does not cross a page boundary */ if (!RecordIsValid(record, *RecPtr, emode)) goto next_record_is_invalid; EndRecPtr.xlogid = RecPtr->xlogid; EndRecPtr.xrecoff = RecPtr->xrecoff + MAXALIGN(total_len); ReadRecPtr = *RecPtr; memcpy(buffer, record, total_len); /* * Special processing if it's an XLOG SWITCH record */ if (record->xl_rmid == RM_XLOG_ID && record->xl_info == XLOG_SWITCH) { /* Pretend it extends to end of segment */ EndRecPtr.xrecoff += XLogSegSize - 1; EndRecPtr.xrecoff -= EndRecPtr.xrecoff % XLogSegSize; /* * Pretend that readBuf contains the last page of the segment. This is * just to avoid Assert failure in StartupXLOG if XLOG ends with this * segment. */ readOff = XLogSegSize - XLOG_BLCKSZ; } return (XLogRecord *) buffer; next_record_is_invalid: failedSources |= readSource; if (readFile >= 0) { close(readFile); readFile = -1; } /* In standby-mode, keep trying */ if (StandbyMode) goto retry; else return NULL; } /* * Check whether the xlog header of a page just read in looks valid. * * This is just a convenience subroutine to avoid duplicated code in * ReadRecord. It's not intended for use from anywhere else. */ static bool ValidXLOGHeader(XLogPageHeader hdr, int emode) { XLogRecPtr recaddr; recaddr.xlogid = readId; recaddr.xrecoff = readSeg * XLogSegSize + readOff; if (hdr->xlp_magic != XLOG_PAGE_MAGIC) { ereport(emode_for_corrupt_record(emode, recaddr), (errmsg("invalid magic number %04X in log file %u, segment %u, offset %u", hdr->xlp_magic, readId, readSeg, readOff))); return false; } if ((hdr->xlp_info & ~XLP_ALL_FLAGS) != 0) { ereport(emode_for_corrupt_record(emode, recaddr), (errmsg("invalid info bits %04X in log file %u, segment %u, offset %u", hdr->xlp_info, readId, readSeg, readOff))); return false; } if (hdr->xlp_info & XLP_LONG_HEADER) { XLogLongPageHeader longhdr = (XLogLongPageHeader) hdr; if (longhdr->xlp_sysid != ControlFile->system_identifier) { char fhdrident_str[32]; char sysident_str[32]; /* * Format sysids separately to keep platform-dependent format code * out of the translatable message string. */ snprintf(fhdrident_str, sizeof(fhdrident_str), UINT64_FORMAT, longhdr->xlp_sysid); snprintf(sysident_str, sizeof(sysident_str), UINT64_FORMAT, ControlFile->system_identifier); ereport(emode_for_corrupt_record(emode, recaddr), (errmsg("WAL file is from different database system"), errdetail("WAL file database system identifier is %s, pg_control database system identifier is %s.", fhdrident_str, sysident_str))); return false; } if (longhdr->xlp_seg_size != XLogSegSize) { ereport(emode_for_corrupt_record(emode, recaddr), (errmsg("WAL file is from different database system"), errdetail("Incorrect XLOG_SEG_SIZE in page header."))); return false; } if (longhdr->xlp_xlog_blcksz != XLOG_BLCKSZ) { ereport(emode_for_corrupt_record(emode, recaddr), (errmsg("WAL file is from different database system"), errdetail("Incorrect XLOG_BLCKSZ in page header."))); return false; } } else if (readOff == 0) { /* hmm, first page of file doesn't have a long header? */ ereport(emode_for_corrupt_record(emode, recaddr), (errmsg("invalid info bits %04X in log file %u, segment %u, offset %u", hdr->xlp_info, readId, readSeg, readOff))); return false; } if (!XLByteEQ(hdr->xlp_pageaddr, recaddr)) { ereport(emode_for_corrupt_record(emode, recaddr), (errmsg("unexpected pageaddr %X/%X in log file %u, segment %u, offset %u", hdr->xlp_pageaddr.xlogid, hdr->xlp_pageaddr.xrecoff, readId, readSeg, readOff))); return false; } /* * Check page TLI is one of the expected values. */ if (!list_member_int(expectedTLIs, (int) hdr->xlp_tli)) { ereport(emode_for_corrupt_record(emode, recaddr), (errmsg("unexpected timeline ID %u in log file %u, segment %u, offset %u", hdr->xlp_tli, readId, readSeg, readOff))); return false; } /* * Since child timelines are always assigned a TLI greater than their * immediate parent's TLI, we should never see TLI go backwards across * successive pages of a consistent WAL sequence. * * Of course this check should only be applied when advancing sequentially * across pages; therefore ReadRecord resets lastPageTLI to zero when * going to a random page. */ if (hdr->xlp_tli < lastPageTLI) { ereport(emode_for_corrupt_record(emode, recaddr), (errmsg("out-of-sequence timeline ID %u (after %u) in log file %u, segment %u, offset %u", hdr->xlp_tli, lastPageTLI, readId, readSeg, readOff))); return false; } lastPageTLI = hdr->xlp_tli; return true; } /* * Try to read a timeline's history file. * * If successful, return the list of component TLIs (the given TLI followed by * its ancestor TLIs). If we can't find the history file, assume that the * timeline has no parents, and return a list of just the specified timeline * ID. */ static List * readTimeLineHistory(TimeLineID targetTLI) { List *result; char path[MAXPGPATH]; char histfname[MAXFNAMELEN]; char fline[MAXPGPATH]; FILE *fd; /* Timeline 1 does not have a history file, so no need to check */ if (targetTLI == 1) return list_make1_int((int) targetTLI); if (InArchiveRecovery) { TLHistoryFileName(histfname, targetTLI); RestoreArchivedFile(path, histfname, "RECOVERYHISTORY", 0); } else TLHistoryFilePath(path, targetTLI); fd = AllocateFile(path, "r"); if (fd == NULL) { if (errno != ENOENT) ereport(FATAL, (errcode_for_file_access(), errmsg("could not open file \"%s\": %m", path))); /* Not there, so assume no parents */ return list_make1_int((int) targetTLI); } result = NIL; /* * Parse the file... */ while (fgets(fline, sizeof(fline), fd) != NULL) { /* skip leading whitespace and check for # comment */ char *ptr; char *endptr; TimeLineID tli; for (ptr = fline; *ptr; ptr++) { if (!isspace((unsigned char) *ptr)) break; } if (*ptr == '\0' || *ptr == '#') continue; /* expect a numeric timeline ID as first field of line */ tli = (TimeLineID) strtoul(ptr, &endptr, 0); if (endptr == ptr) ereport(FATAL, (errmsg("syntax error in history file: %s", fline), errhint("Expected a numeric timeline ID."))); if (result && tli <= (TimeLineID) linitial_int(result)) ereport(FATAL, (errmsg("invalid data in history file: %s", fline), errhint("Timeline IDs must be in increasing sequence."))); /* Build list with newest item first */ result = lcons_int((int) tli, result); /* we ignore the remainder of each line */ } FreeFile(fd); if (result && targetTLI <= (TimeLineID) linitial_int(result)) ereport(FATAL, (errmsg("invalid data in history file \"%s\"", path), errhint("Timeline IDs must be less than child timeline's ID."))); result = lcons_int((int) targetTLI, result); ereport(DEBUG3, (errmsg_internal("history of timeline %u is %s", targetTLI, nodeToString(result)))); return result; } /* * Probe whether a timeline history file exists for the given timeline ID */ static bool existsTimeLineHistory(TimeLineID probeTLI) { char path[MAXPGPATH]; char histfname[MAXFNAMELEN]; FILE *fd; /* Timeline 1 does not have a history file, so no need to check */ if (probeTLI == 1) return false; if (InArchiveRecovery) { TLHistoryFileName(histfname, probeTLI); RestoreArchivedFile(path, histfname, "RECOVERYHISTORY", 0); } else TLHistoryFilePath(path, probeTLI); fd = AllocateFile(path, "r"); if (fd != NULL) { FreeFile(fd); return true; } else { if (errno != ENOENT) ereport(FATAL, (errcode_for_file_access(), errmsg("could not open file \"%s\": %m", path))); return false; } } /* * Scan for new timelines that might have appeared in the archive since we * started recovery. * * If there are any, the function changes recovery target TLI to the latest * one and returns 'true'. */ static bool rescanLatestTimeLine(void) { TimeLineID newtarget; newtarget = findNewestTimeLine(recoveryTargetTLI); if (newtarget != recoveryTargetTLI) { /* * Determine the list of expected TLIs for the new TLI */ List *newExpectedTLIs; newExpectedTLIs = readTimeLineHistory(newtarget); /* * If the current timeline is not part of the history of the new * timeline, we cannot proceed to it. * * XXX This isn't foolproof: The new timeline might have forked from * the current one, but before the current recovery location. In that * case we will still switch to the new timeline and proceed replaying * from it even though the history doesn't match what we already * replayed. That's not good. We will likely notice at the next online * checkpoint, as the TLI won't match what we expected, but it's not * guaranteed. The admin needs to make sure that doesn't happen. */ if (!list_member_int(newExpectedTLIs, (int) recoveryTargetTLI)) ereport(LOG, (errmsg("new timeline %u is not a child of database system timeline %u", newtarget, ThisTimeLineID))); else { /* Switch target */ recoveryTargetTLI = newtarget; list_free(expectedTLIs); expectedTLIs = newExpectedTLIs; XLogCtl->RecoveryTargetTLI = recoveryTargetTLI; ereport(LOG, (errmsg("new target timeline is %u", recoveryTargetTLI))); return true; } } return false; } /* * Find the newest existing timeline, assuming that startTLI exists. * * Note: while this is somewhat heuristic, it does positively guarantee * that (result + 1) is not a known timeline, and therefore it should * be safe to assign that ID to a new timeline. */ static TimeLineID findNewestTimeLine(TimeLineID startTLI) { TimeLineID newestTLI; TimeLineID probeTLI; /* * The algorithm is just to probe for the existence of timeline history * files. XXX is it useful to allow gaps in the sequence? */ newestTLI = startTLI; for (probeTLI = startTLI + 1;; probeTLI++) { if (existsTimeLineHistory(probeTLI)) { newestTLI = probeTLI; /* probeTLI exists */ } else { /* doesn't exist, assume we're done */ break; } } return newestTLI; } /* * Create a new timeline history file. * * newTLI: ID of the new timeline * parentTLI: ID of its immediate parent * endTLI et al: ID of the last used WAL file, for annotation purposes * * Currently this is only used during recovery, and so there are no locking * considerations. But we should be just as tense as XLogFileInit to avoid * emplacing a bogus file. */ static void writeTimeLineHistory(TimeLineID newTLI, TimeLineID parentTLI, TimeLineID endTLI, uint32 endLogId, uint32 endLogSeg) { char path[MAXPGPATH]; char tmppath[MAXPGPATH]; char histfname[MAXFNAMELEN]; char xlogfname[MAXFNAMELEN]; char buffer[BLCKSZ]; int srcfd; int fd; int nbytes; Assert(newTLI > parentTLI); /* else bad selection of newTLI */ /* * Write into a temp file name. */ snprintf(tmppath, MAXPGPATH, XLOGDIR "/xlogtemp.%d", (int) getpid()); unlink(tmppath); /* do not use get_sync_bit() here --- want to fsync only at end of fill */ fd = BasicOpenFile(tmppath, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR); if (fd < 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not create file \"%s\": %m", tmppath))); /* * If a history file exists for the parent, copy it verbatim */ if (InArchiveRecovery) { TLHistoryFileName(histfname, parentTLI); RestoreArchivedFile(path, histfname, "RECOVERYHISTORY", 0); } else TLHistoryFilePath(path, parentTLI); srcfd = BasicOpenFile(path, O_RDONLY, 0); if (srcfd < 0) { if (errno != ENOENT) ereport(ERROR, (errcode_for_file_access(), errmsg("could not open file \"%s\": %m", path))); /* Not there, so assume parent has no parents */ } else { for (;;) { errno = 0; nbytes = (int) read(srcfd, buffer, sizeof(buffer)); if (nbytes < 0 || errno != 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not read file \"%s\": %m", path))); if (nbytes == 0) break; errno = 0; if ((int) write(fd, buffer, nbytes) != nbytes) { int save_errno = errno; /* * If we fail to make the file, delete it to release disk * space */ unlink(tmppath); /* * if write didn't set errno, assume problem is no disk space */ errno = save_errno ? save_errno : ENOSPC; ereport(ERROR, (errcode_for_file_access(), errmsg("could not write to file \"%s\": %m", tmppath))); } } close(srcfd); } /* * Append one line with the details of this timeline split. * * If we did have a parent file, insert an extra newline just in case the * parent file failed to end with one. */ XLogFileName(xlogfname, endTLI, endLogId, endLogSeg); /* * Write comment to history file to explain why and where timeline * changed. Comment varies according to the recovery target used. */ if (recoveryTarget == RECOVERY_TARGET_XID) snprintf(buffer, sizeof(buffer), "%s%u\t%s\t%s transaction %u\n", (srcfd < 0) ? "" : "\n", parentTLI, xlogfname, recoveryStopAfter ? "after" : "before", recoveryStopXid); else if (recoveryTarget == RECOVERY_TARGET_TIME) snprintf(buffer, sizeof(buffer), "%s%u\t%s\t%s %s\n", (srcfd < 0) ? "" : "\n", parentTLI, xlogfname, recoveryStopAfter ? "after" : "before", timestamptz_to_str(recoveryStopTime)); else if (recoveryTarget == RECOVERY_TARGET_NAME) snprintf(buffer, sizeof(buffer), "%s%u\t%s\tat restore point \"%s\"\n", (srcfd < 0) ? "" : "\n", parentTLI, xlogfname, recoveryStopName); else snprintf(buffer, sizeof(buffer), "%s%u\t%s\tno recovery target specified\n", (srcfd < 0) ? "" : "\n", parentTLI, xlogfname); nbytes = strlen(buffer); errno = 0; if ((int) write(fd, buffer, nbytes) != nbytes) { int save_errno = errno; /* * If we fail to make the file, delete it to release disk space */ unlink(tmppath); /* if write didn't set errno, assume problem is no disk space */ errno = save_errno ? save_errno : ENOSPC; ereport(ERROR, (errcode_for_file_access(), errmsg("could not write to file \"%s\": %m", tmppath))); } if (pg_fsync(fd) != 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not fsync file \"%s\": %m", tmppath))); if (close(fd)) ereport(ERROR, (errcode_for_file_access(), errmsg("could not close file \"%s\": %m", tmppath))); /* * Now move the completed history file into place with its final name. */ TLHistoryFilePath(path, newTLI); /* * Prefer link() to rename() here just to be really sure that we don't * overwrite an existing logfile. However, there shouldn't be one, so * rename() is an acceptable substitute except for the truly paranoid. */ #if HAVE_WORKING_LINK if (link(tmppath, path) < 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not link file \"%s\" to \"%s\": %m", tmppath, path))); unlink(tmppath); #else if (rename(tmppath, path) < 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not rename file \"%s\" to \"%s\": %m", tmppath, path))); #endif /* The history file can be archived immediately. */ TLHistoryFileName(histfname, newTLI); XLogArchiveNotify(histfname); } /* * I/O routines for pg_control * * *ControlFile is a buffer in shared memory that holds an image of the * contents of pg_control. WriteControlFile() initializes pg_control * given a preloaded buffer, ReadControlFile() loads the buffer from * the pg_control file (during postmaster or standalone-backend startup), * and UpdateControlFile() rewrites pg_control after we modify xlog state. * * For simplicity, WriteControlFile() initializes the fields of pg_control * that are related to checking backend/database compatibility, and * ReadControlFile() verifies they are correct. We could split out the * I/O and compatibility-check functions, but there seems no need currently. */ static void WriteControlFile(void) { int fd; char buffer[PG_CONTROL_SIZE]; /* need not be aligned */ /* * Initialize version and compatibility-check fields */ ControlFile->pg_control_version = PG_CONTROL_VERSION; ControlFile->catalog_version_no = CATALOG_VERSION_NO; ControlFile->maxAlign = MAXIMUM_ALIGNOF; ControlFile->floatFormat = FLOATFORMAT_VALUE; ControlFile->blcksz = BLCKSZ; ControlFile->relseg_size = RELSEG_SIZE; ControlFile->xlog_blcksz = XLOG_BLCKSZ; ControlFile->xlog_seg_size = XLOG_SEG_SIZE; ControlFile->nameDataLen = NAMEDATALEN; ControlFile->indexMaxKeys = INDEX_MAX_KEYS; ControlFile->toast_max_chunk_size = TOAST_MAX_CHUNK_SIZE; #ifdef HAVE_INT64_TIMESTAMP ControlFile->enableIntTimes = true; #else ControlFile->enableIntTimes = false; #endif ControlFile->float4ByVal = FLOAT4PASSBYVAL; ControlFile->float8ByVal = FLOAT8PASSBYVAL; /* Contents are protected with a CRC */ INIT_CRC32(ControlFile->crc); COMP_CRC32(ControlFile->crc, (char *) ControlFile, offsetof(ControlFileData, crc)); FIN_CRC32(ControlFile->crc); /* * We write out PG_CONTROL_SIZE bytes into pg_control, zero-padding the * excess over sizeof(ControlFileData). This reduces the odds of * premature-EOF errors when reading pg_control. We'll still fail when we * check the contents of the file, but hopefully with a more specific * error than "couldn't read pg_control". */ if (sizeof(ControlFileData) > PG_CONTROL_SIZE) elog(PANIC, "sizeof(ControlFileData) is larger than PG_CONTROL_SIZE; fix either one"); memset(buffer, 0, PG_CONTROL_SIZE); memcpy(buffer, ControlFile, sizeof(ControlFileData)); fd = BasicOpenFile(XLOG_CONTROL_FILE, O_RDWR | O_CREAT | O_EXCL | PG_BINARY, S_IRUSR | S_IWUSR); if (fd < 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not create control file \"%s\": %m", XLOG_CONTROL_FILE))); errno = 0; if (write(fd, buffer, PG_CONTROL_SIZE) != PG_CONTROL_SIZE) { /* if write didn't set errno, assume problem is no disk space */ if (errno == 0) errno = ENOSPC; ereport(PANIC, (errcode_for_file_access(), errmsg("could not write to control file: %m"))); } if (pg_fsync(fd) != 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not fsync control file: %m"))); if (close(fd)) ereport(PANIC, (errcode_for_file_access(), errmsg("could not close control file: %m"))); } static void ReadControlFile(void) { pg_crc32 crc; int fd; /* * Read data... */ fd = BasicOpenFile(XLOG_CONTROL_FILE, O_RDWR | PG_BINARY, S_IRUSR | S_IWUSR); if (fd < 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not open control file \"%s\": %m", XLOG_CONTROL_FILE))); if (read(fd, ControlFile, sizeof(ControlFileData)) != sizeof(ControlFileData)) ereport(PANIC, (errcode_for_file_access(), errmsg("could not read from control file: %m"))); close(fd); /* * Check for expected pg_control format version. If this is wrong, the * CRC check will likely fail because we'll be checking the wrong number * of bytes. Complaining about wrong version will probably be more * enlightening than complaining about wrong CRC. */ if (ControlFile->pg_control_version != PG_CONTROL_VERSION && ControlFile->pg_control_version % 65536 == 0 && ControlFile->pg_control_version / 65536 != 0) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with PG_CONTROL_VERSION %d (0x%08x)," " but the server was compiled with PG_CONTROL_VERSION %d (0x%08x).", ControlFile->pg_control_version, ControlFile->pg_control_version, PG_CONTROL_VERSION, PG_CONTROL_VERSION), errhint("This could be a problem of mismatched byte ordering. It looks like you need to initdb."))); if (ControlFile->pg_control_version != PG_CONTROL_VERSION) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with PG_CONTROL_VERSION %d," " but the server was compiled with PG_CONTROL_VERSION %d.", ControlFile->pg_control_version, PG_CONTROL_VERSION), errhint("It looks like you need to initdb."))); /* Now check the CRC. */ INIT_CRC32(crc); COMP_CRC32(crc, (char *) ControlFile, offsetof(ControlFileData, crc)); FIN_CRC32(crc); if (!EQ_CRC32(crc, ControlFile->crc)) ereport(FATAL, (errmsg("incorrect checksum in control file"))); /* * Do compatibility checking immediately. If the database isn't * compatible with the backend executable, we want to abort before we can * possibly do any damage. */ if (ControlFile->catalog_version_no != CATALOG_VERSION_NO) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with CATALOG_VERSION_NO %d," " but the server was compiled with CATALOG_VERSION_NO %d.", ControlFile->catalog_version_no, CATALOG_VERSION_NO), errhint("It looks like you need to initdb."))); if (ControlFile->maxAlign != MAXIMUM_ALIGNOF) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with MAXALIGN %d," " but the server was compiled with MAXALIGN %d.", ControlFile->maxAlign, MAXIMUM_ALIGNOF), errhint("It looks like you need to initdb."))); if (ControlFile->floatFormat != FLOATFORMAT_VALUE) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster appears to use a different floating-point number format than the server executable."), errhint("It looks like you need to initdb."))); if (ControlFile->blcksz != BLCKSZ) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with BLCKSZ %d," " but the server was compiled with BLCKSZ %d.", ControlFile->blcksz, BLCKSZ), errhint("It looks like you need to recompile or initdb."))); if (ControlFile->relseg_size != RELSEG_SIZE) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with RELSEG_SIZE %d," " but the server was compiled with RELSEG_SIZE %d.", ControlFile->relseg_size, RELSEG_SIZE), errhint("It looks like you need to recompile or initdb."))); if (ControlFile->xlog_blcksz != XLOG_BLCKSZ) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with XLOG_BLCKSZ %d," " but the server was compiled with XLOG_BLCKSZ %d.", ControlFile->xlog_blcksz, XLOG_BLCKSZ), errhint("It looks like you need to recompile or initdb."))); if (ControlFile->xlog_seg_size != XLOG_SEG_SIZE) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with XLOG_SEG_SIZE %d," " but the server was compiled with XLOG_SEG_SIZE %d.", ControlFile->xlog_seg_size, XLOG_SEG_SIZE), errhint("It looks like you need to recompile or initdb."))); if (ControlFile->nameDataLen != NAMEDATALEN) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with NAMEDATALEN %d," " but the server was compiled with NAMEDATALEN %d.", ControlFile->nameDataLen, NAMEDATALEN), errhint("It looks like you need to recompile or initdb."))); if (ControlFile->indexMaxKeys != INDEX_MAX_KEYS) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with INDEX_MAX_KEYS %d," " but the server was compiled with INDEX_MAX_KEYS %d.", ControlFile->indexMaxKeys, INDEX_MAX_KEYS), errhint("It looks like you need to recompile or initdb."))); if (ControlFile->toast_max_chunk_size != TOAST_MAX_CHUNK_SIZE) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with TOAST_MAX_CHUNK_SIZE %d," " but the server was compiled with TOAST_MAX_CHUNK_SIZE %d.", ControlFile->toast_max_chunk_size, (int) TOAST_MAX_CHUNK_SIZE), errhint("It looks like you need to recompile or initdb."))); #ifdef HAVE_INT64_TIMESTAMP if (ControlFile->enableIntTimes != true) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized without HAVE_INT64_TIMESTAMP" " but the server was compiled with HAVE_INT64_TIMESTAMP."), errhint("It looks like you need to recompile or initdb."))); #else if (ControlFile->enableIntTimes != false) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with HAVE_INT64_TIMESTAMP" " but the server was compiled without HAVE_INT64_TIMESTAMP."), errhint("It looks like you need to recompile or initdb."))); #endif #ifdef USE_FLOAT4_BYVAL if (ControlFile->float4ByVal != true) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized without USE_FLOAT4_BYVAL" " but the server was compiled with USE_FLOAT4_BYVAL."), errhint("It looks like you need to recompile or initdb."))); #else if (ControlFile->float4ByVal != false) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with USE_FLOAT4_BYVAL" " but the server was compiled without USE_FLOAT4_BYVAL."), errhint("It looks like you need to recompile or initdb."))); #endif #ifdef USE_FLOAT8_BYVAL if (ControlFile->float8ByVal != true) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized without USE_FLOAT8_BYVAL" " but the server was compiled with USE_FLOAT8_BYVAL."), errhint("It looks like you need to recompile or initdb."))); #else if (ControlFile->float8ByVal != false) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with USE_FLOAT8_BYVAL" " but the server was compiled without USE_FLOAT8_BYVAL."), errhint("It looks like you need to recompile or initdb."))); #endif } void UpdateControlFile(void) { int fd; INIT_CRC32(ControlFile->crc); COMP_CRC32(ControlFile->crc, (char *) ControlFile, offsetof(ControlFileData, crc)); FIN_CRC32(ControlFile->crc); fd = BasicOpenFile(XLOG_CONTROL_FILE, O_RDWR | PG_BINARY, S_IRUSR | S_IWUSR); if (fd < 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not open control file \"%s\": %m", XLOG_CONTROL_FILE))); errno = 0; if (write(fd, ControlFile, sizeof(ControlFileData)) != sizeof(ControlFileData)) { /* if write didn't set errno, assume problem is no disk space */ if (errno == 0) errno = ENOSPC; ereport(PANIC, (errcode_for_file_access(), errmsg("could not write to control file: %m"))); } if (pg_fsync(fd) != 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not fsync control file: %m"))); if (close(fd)) ereport(PANIC, (errcode_for_file_access(), errmsg("could not close control file: %m"))); } /* * Returns the unique system identifier from control file. */ uint64 GetSystemIdentifier(void) { Assert(ControlFile != NULL); return ControlFile->system_identifier; } /* * Auto-tune the number of XLOG buffers. * * The preferred setting for wal_buffers is about 3% of shared_buffers, with * a maximum of one XLOG segment (there is little reason to think that more * is helpful, at least so long as we force an fsync when switching log files) * and a minimum of 8 blocks (which was the default value prior to PostgreSQL * 9.1, when auto-tuning was added). * * This should not be called until NBuffers has received its final value. */ static int XLOGChooseNumBuffers(void) { int xbuffers; xbuffers = NBuffers / 32; if (xbuffers > XLOG_SEG_SIZE / XLOG_BLCKSZ) xbuffers = XLOG_SEG_SIZE / XLOG_BLCKSZ; if (xbuffers < 8) xbuffers = 8; return xbuffers; } /* * GUC check_hook for wal_buffers */ bool check_wal_buffers(int *newval, void **extra, GucSource source) { /* * -1 indicates a request for auto-tune. */ if (*newval == -1) { /* * If we haven't yet changed the boot_val default of -1, just let it * be. We'll fix it when XLOGShmemSize is called. */ if (XLOGbuffers == -1) return true; /* Otherwise, substitute the auto-tune value */ *newval = XLOGChooseNumBuffers(); } /* * We clamp manually-set values to at least 4 blocks. Prior to PostgreSQL * 9.1, a minimum of 4 was enforced by guc.c, but since that is no longer * the case, we just silently treat such values as a request for the * minimum. (We could throw an error instead, but that doesn't seem very * helpful.) */ if (*newval < 4) *newval = 4; return true; } /* * Initialization of shared memory for XLOG */ Size XLOGShmemSize(void) { Size size; /* * If the value of wal_buffers is -1, use the preferred auto-tune value. * This isn't an amazingly clean place to do this, but we must wait till * NBuffers has received its final value, and must do it before using the * value of XLOGbuffers to do anything important. */ if (XLOGbuffers == -1) { char buf[32]; snprintf(buf, sizeof(buf), "%d", XLOGChooseNumBuffers()); SetConfigOption("wal_buffers", buf, PGC_POSTMASTER, PGC_S_OVERRIDE); } Assert(XLOGbuffers > 0); /* XLogCtl */ size = sizeof(XLogCtlData); /* xlblocks array */ size = add_size(size, mul_size(sizeof(XLogRecPtr), XLOGbuffers)); /* extra alignment padding for XLOG I/O buffers */ size = add_size(size, ALIGNOF_XLOG_BUFFER); /* and the buffers themselves */ size = add_size(size, mul_size(XLOG_BLCKSZ, XLOGbuffers)); /* * Note: we don't count ControlFileData, it comes out of the "slop factor" * added by CreateSharedMemoryAndSemaphores. This lets us use this * routine again below to compute the actual allocation size. */ return size; } void XLOGShmemInit(void) { bool foundCFile, foundXLog; char *allocptr; ControlFile = (ControlFileData *) ShmemInitStruct("Control File", sizeof(ControlFileData), &foundCFile); XLogCtl = (XLogCtlData *) ShmemInitStruct("XLOG Ctl", XLOGShmemSize(), &foundXLog); if (foundCFile || foundXLog) { /* both should be present or neither */ Assert(foundCFile && foundXLog); return; } memset(XLogCtl, 0, sizeof(XLogCtlData)); /* * Since XLogCtlData contains XLogRecPtr fields, its sizeof should be a * multiple of the alignment for same, so no extra alignment padding is * needed here. */ allocptr = ((char *) XLogCtl) + sizeof(XLogCtlData); XLogCtl->xlblocks = (XLogRecPtr *) allocptr; memset(XLogCtl->xlblocks, 0, sizeof(XLogRecPtr) * XLOGbuffers); allocptr += sizeof(XLogRecPtr) * XLOGbuffers; /* * Align the start of the page buffers to an ALIGNOF_XLOG_BUFFER boundary. */ allocptr = (char *) TYPEALIGN(ALIGNOF_XLOG_BUFFER, allocptr); XLogCtl->pages = allocptr; memset(XLogCtl->pages, 0, (Size) XLOG_BLCKSZ * XLOGbuffers); /* * Do basic initialization of XLogCtl shared data. (StartupXLOG will fill * in additional info.) */ XLogCtl->XLogCacheBlck = XLOGbuffers - 1; XLogCtl->SharedRecoveryInProgress = true; XLogCtl->SharedHotStandbyActive = false; XLogCtl->WalWriterSleeping = false; XLogCtl->Insert.currpage = (XLogPageHeader) (XLogCtl->pages); SpinLockInit(&XLogCtl->info_lck); InitSharedLatch(&XLogCtl->recoveryWakeupLatch); /* * If we are not in bootstrap mode, pg_control should already exist. Read * and validate it immediately (see comments in ReadControlFile() for the * reasons why). */ if (!IsBootstrapProcessingMode()) ReadControlFile(); } /* * This func must be called ONCE on system install. It creates pg_control * and the initial XLOG segment. */ void BootStrapXLOG(void) { CheckPoint checkPoint; char *buffer; XLogPageHeader page; XLogLongPageHeader longpage; XLogRecord *record; bool use_existent; uint64 sysidentifier; struct timeval tv; pg_crc32 crc; /* * Select a hopefully-unique system identifier code for this installation. * We use the result of gettimeofday(), including the fractional seconds * field, as being about as unique as we can easily get. (Think not to * use random(), since it hasn't been seeded and there's no portable way * to seed it other than the system clock value...) The upper half of the * uint64 value is just the tv_sec part, while the lower half is the XOR * of tv_sec and tv_usec. This is to ensure that we don't lose uniqueness * unnecessarily if "uint64" is really only 32 bits wide. A person * knowing this encoding can determine the initialization time of the * installation, which could perhaps be useful sometimes. */ gettimeofday(&tv, NULL); sysidentifier = ((uint64) tv.tv_sec) << 32; sysidentifier |= (uint32) (tv.tv_sec | tv.tv_usec); /* First timeline ID is always 1 */ ThisTimeLineID = 1; /* page buffer must be aligned suitably for O_DIRECT */ buffer = (char *) palloc(XLOG_BLCKSZ + ALIGNOF_XLOG_BUFFER); page = (XLogPageHeader) TYPEALIGN(ALIGNOF_XLOG_BUFFER, buffer); memset(page, 0, XLOG_BLCKSZ); /* * Set up information for the initial checkpoint record * * The initial checkpoint record is written to the beginning of the WAL * segment with logid=0 logseg=1. The very first WAL segment, 0/0, is not * used, so that we can use 0/0 to mean "before any valid WAL segment". */ checkPoint.redo.xlogid = 0; checkPoint.redo.xrecoff = XLogSegSize + SizeOfXLogLongPHD; checkPoint.ThisTimeLineID = ThisTimeLineID; checkPoint.fullPageWrites = fullPageWrites; checkPoint.nextXidEpoch = 0; checkPoint.nextXid = FirstNormalTransactionId; checkPoint.nextOid = FirstBootstrapObjectId; checkPoint.nextMulti = FirstMultiXactId; checkPoint.nextMultiOffset = 0; checkPoint.oldestXid = FirstNormalTransactionId; checkPoint.oldestXidDB = TemplateDbOid; checkPoint.time = (pg_time_t) time(NULL); checkPoint.oldestActiveXid = InvalidTransactionId; ShmemVariableCache->nextXid = checkPoint.nextXid; ShmemVariableCache->nextOid = checkPoint.nextOid; ShmemVariableCache->oidCount = 0; MultiXactSetNextMXact(checkPoint.nextMulti, checkPoint.nextMultiOffset); SetTransactionIdLimit(checkPoint.oldestXid, checkPoint.oldestXidDB); /* Set up the XLOG page header */ page->xlp_magic = XLOG_PAGE_MAGIC; page->xlp_info = XLP_LONG_HEADER; page->xlp_tli = ThisTimeLineID; page->xlp_pageaddr.xlogid = 0; page->xlp_pageaddr.xrecoff = XLogSegSize; longpage = (XLogLongPageHeader) page; longpage->xlp_sysid = sysidentifier; longpage->xlp_seg_size = XLogSegSize; longpage->xlp_xlog_blcksz = XLOG_BLCKSZ; /* Insert the initial checkpoint record */ record = (XLogRecord *) ((char *) page + SizeOfXLogLongPHD); record->xl_prev.xlogid = 0; record->xl_prev.xrecoff = 0; record->xl_xid = InvalidTransactionId; record->xl_tot_len = SizeOfXLogRecord + sizeof(checkPoint); record->xl_len = sizeof(checkPoint); record->xl_info = XLOG_CHECKPOINT_SHUTDOWN; record->xl_rmid = RM_XLOG_ID; memcpy(XLogRecGetData(record), &checkPoint, sizeof(checkPoint)); INIT_CRC32(crc); COMP_CRC32(crc, &checkPoint, sizeof(checkPoint)); COMP_CRC32(crc, (char *) record + sizeof(pg_crc32), SizeOfXLogRecord - sizeof(pg_crc32)); FIN_CRC32(crc); record->xl_crc = crc; /* Create first XLOG segment file */ use_existent = false; openLogFile = XLogFileInit(0, 1, &use_existent, false); /* Write the first page with the initial record */ errno = 0; if (write(openLogFile, page, XLOG_BLCKSZ) != XLOG_BLCKSZ) { /* if write didn't set errno, assume problem is no disk space */ if (errno == 0) errno = ENOSPC; ereport(PANIC, (errcode_for_file_access(), errmsg("could not write bootstrap transaction log file: %m"))); } if (pg_fsync(openLogFile) != 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not fsync bootstrap transaction log file: %m"))); if (close(openLogFile)) ereport(PANIC, (errcode_for_file_access(), errmsg("could not close bootstrap transaction log file: %m"))); openLogFile = -1; /* Now create pg_control */ memset(ControlFile, 0, sizeof(ControlFileData)); /* Initialize pg_control status fields */ ControlFile->system_identifier = sysidentifier; ControlFile->state = DB_SHUTDOWNED; ControlFile->time = checkPoint.time; ControlFile->checkPoint = checkPoint.redo; ControlFile->checkPointCopy = checkPoint; /* Set important parameter values for use when replaying WAL */ ControlFile->MaxConnections = MaxConnections; ControlFile->max_prepared_xacts = max_prepared_xacts; ControlFile->max_locks_per_xact = max_locks_per_xact; ControlFile->wal_level = wal_level; /* some additional ControlFile fields are set in WriteControlFile() */ WriteControlFile(); /* Bootstrap the commit log, too */ BootStrapCLOG(); BootStrapSUBTRANS(); BootStrapMultiXact(); pfree(buffer); } static char * str_time(pg_time_t tnow) { static char buf[128]; pg_strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S %Z", pg_localtime(&tnow, log_timezone)); return buf; } /* * See if there is a recovery command file (recovery.conf), and if so * read in parameters for archive recovery and XLOG streaming. * * The file is parsed using the main configuration parser. */ static void readRecoveryCommandFile(void) { FILE *fd; TimeLineID rtli = 0; bool rtliGiven = false; ConfigVariable *item, *head = NULL, *tail = NULL; fd = AllocateFile(RECOVERY_COMMAND_FILE, "r"); if (fd == NULL) { if (errno == ENOENT) return; /* not there, so no archive recovery */ ereport(FATAL, (errcode_for_file_access(), errmsg("could not open recovery command file \"%s\": %m", RECOVERY_COMMAND_FILE))); } /* * Since we're asking ParseConfigFp() to report errors as FATAL, there's * no need to check the return value. */ (void) ParseConfigFp(fd, RECOVERY_COMMAND_FILE, 0, FATAL, &head, &tail); FreeFile(fd); for (item = head; item; item = item->next) { if (strcmp(item->name, "restore_command") == 0) { recoveryRestoreCommand = pstrdup(item->value); ereport(DEBUG2, (errmsg_internal("restore_command = '%s'", recoveryRestoreCommand))); } else if (strcmp(item->name, "recovery_end_command") == 0) { recoveryEndCommand = pstrdup(item->value); ereport(DEBUG2, (errmsg_internal("recovery_end_command = '%s'", recoveryEndCommand))); } else if (strcmp(item->name, "archive_cleanup_command") == 0) { archiveCleanupCommand = pstrdup(item->value); ereport(DEBUG2, (errmsg_internal("archive_cleanup_command = '%s'", archiveCleanupCommand))); } else if (strcmp(item->name, "pause_at_recovery_target") == 0) { if (!parse_bool(item->value, &recoveryPauseAtTarget)) ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("parameter \"%s\" requires a Boolean value", "pause_at_recovery_target"))); ereport(DEBUG2, (errmsg_internal("pause_at_recovery_target = '%s'", item->value))); } else if (strcmp(item->name, "recovery_target_timeline") == 0) { rtliGiven = true; if (strcmp(item->value, "latest") == 0) rtli = 0; else { errno = 0; rtli = (TimeLineID) strtoul(item->value, NULL, 0); if (errno == EINVAL || errno == ERANGE) ereport(FATAL, (errmsg("recovery_target_timeline is not a valid number: \"%s\"", item->value))); } if (rtli) ereport(DEBUG2, (errmsg_internal("recovery_target_timeline = %u", rtli))); else ereport(DEBUG2, (errmsg_internal("recovery_target_timeline = latest"))); } else if (strcmp(item->name, "recovery_target_xid") == 0) { errno = 0; recoveryTargetXid = (TransactionId) strtoul(item->value, NULL, 0); if (errno == EINVAL || errno == ERANGE) ereport(FATAL, (errmsg("recovery_target_xid is not a valid number: \"%s\"", item->value))); ereport(DEBUG2, (errmsg_internal("recovery_target_xid = %u", recoveryTargetXid))); recoveryTarget = RECOVERY_TARGET_XID; } else if (strcmp(item->name, "recovery_target_time") == 0) { /* * if recovery_target_xid or recovery_target_name specified, then * this overrides recovery_target_time */ if (recoveryTarget == RECOVERY_TARGET_XID || recoveryTarget == RECOVERY_TARGET_NAME) continue; recoveryTarget = RECOVERY_TARGET_TIME; /* * Convert the time string given by the user to TimestampTz form. */ recoveryTargetTime = DatumGetTimestampTz(DirectFunctionCall3(timestamptz_in, CStringGetDatum(item->value), ObjectIdGetDatum(InvalidOid), Int32GetDatum(-1))); ereport(DEBUG2, (errmsg_internal("recovery_target_time = '%s'", timestamptz_to_str(recoveryTargetTime)))); } else if (strcmp(item->name, "recovery_target_name") == 0) { /* * if recovery_target_xid specified, then this overrides * recovery_target_name */ if (recoveryTarget == RECOVERY_TARGET_XID) continue; recoveryTarget = RECOVERY_TARGET_NAME; recoveryTargetName = pstrdup(item->value); if (strlen(recoveryTargetName) >= MAXFNAMELEN) ereport(FATAL, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("recovery_target_name is too long (maximum %d characters)", MAXFNAMELEN - 1))); ereport(DEBUG2, (errmsg_internal("recovery_target_name = '%s'", recoveryTargetName))); } else if (strcmp(item->name, "recovery_target_inclusive") == 0) { /* * does nothing if a recovery_target is not also set */ if (!parse_bool(item->value, &recoveryTargetInclusive)) ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("parameter \"%s\" requires a Boolean value", "recovery_target_inclusive"))); ereport(DEBUG2, (errmsg_internal("recovery_target_inclusive = %s", item->value))); } else if (strcmp(item->name, "standby_mode") == 0) { if (!parse_bool(item->value, &StandbyMode)) ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("parameter \"%s\" requires a Boolean value", "standby_mode"))); ereport(DEBUG2, (errmsg_internal("standby_mode = '%s'", item->value))); } else if (strcmp(item->name, "primary_conninfo") == 0) { PrimaryConnInfo = pstrdup(item->value); ereport(DEBUG2, (errmsg_internal("primary_conninfo = '%s'", PrimaryConnInfo))); } else if (strcmp(item->name, "trigger_file") == 0) { TriggerFile = pstrdup(item->value); ereport(DEBUG2, (errmsg_internal("trigger_file = '%s'", TriggerFile))); } else ereport(FATAL, (errmsg("unrecognized recovery parameter \"%s\"", item->name))); } /* * Check for compulsory parameters */ if (StandbyMode) { if (PrimaryConnInfo == NULL && recoveryRestoreCommand == NULL) ereport(WARNING, (errmsg("recovery command file \"%s\" specified neither primary_conninfo nor restore_command", RECOVERY_COMMAND_FILE), errhint("The database server will regularly poll the pg_xlog subdirectory to check for files placed there."))); } else { if (recoveryRestoreCommand == NULL) ereport(FATAL, (errmsg("recovery command file \"%s\" must specify restore_command when standby mode is not enabled", RECOVERY_COMMAND_FILE))); } /* Enable fetching from archive recovery area */ InArchiveRecovery = true; /* * If user specified recovery_target_timeline, validate it or compute the * "latest" value. We can't do this until after we've gotten the restore * command and set InArchiveRecovery, because we need to fetch timeline * history files from the archive. */ if (rtliGiven) { if (rtli) { /* Timeline 1 does not have a history file, all else should */ if (rtli != 1 && !existsTimeLineHistory(rtli)) ereport(FATAL, (errmsg("recovery target timeline %u does not exist", rtli))); recoveryTargetTLI = rtli; recoveryTargetIsLatest = false; } else { /* We start the "latest" search from pg_control's timeline */ recoveryTargetTLI = findNewestTimeLine(recoveryTargetTLI); recoveryTargetIsLatest = true; } } FreeConfigVariables(head); } /* * Exit archive-recovery state */ static void exitArchiveRecovery(TimeLineID endTLI, uint32 endLogId, uint32 endLogSeg) { char recoveryPath[MAXPGPATH]; char xlogpath[MAXPGPATH]; /* * We are no longer in archive recovery state. */ InArchiveRecovery = false; /* * Update min recovery point one last time. */ UpdateMinRecoveryPoint(InvalidXLogRecPtr, true); /* * If the ending log segment is still open, close it (to avoid problems on * Windows with trying to rename or delete an open file). */ if (readFile >= 0) { close(readFile); readFile = -1; } /* * If we are establishing a new timeline, we have to copy data from the * last WAL segment of the old timeline to create a starting WAL segment * for the new timeline. * * Notify the archiver that the last WAL segment of the old timeline is * ready to copy to archival storage. Otherwise, it is not archived for a * while. */ if (endTLI != ThisTimeLineID) { XLogFileCopy(endLogId, endLogSeg, endTLI, endLogId, endLogSeg); if (XLogArchivingActive()) { XLogFileName(xlogpath, endTLI, endLogId, endLogSeg); XLogArchiveNotify(xlogpath); } } /* * Let's just make real sure there are not .ready or .done flags posted * for the new segment. */ XLogFileName(xlogpath, ThisTimeLineID, endLogId, endLogSeg); XLogArchiveCleanup(xlogpath); /* * Since there might be a partial WAL segment named RECOVERYXLOG, get rid * of it. */ snprintf(recoveryPath, MAXPGPATH, XLOGDIR "/RECOVERYXLOG"); unlink(recoveryPath); /* ignore any error */ /* Get rid of any remaining recovered timeline-history file, too */ snprintf(recoveryPath, MAXPGPATH, XLOGDIR "/RECOVERYHISTORY"); unlink(recoveryPath); /* ignore any error */ /* * Rename the config file out of the way, so that we don't accidentally * re-enter archive recovery mode in a subsequent crash. */ unlink(RECOVERY_COMMAND_DONE); if (rename(RECOVERY_COMMAND_FILE, RECOVERY_COMMAND_DONE) != 0) ereport(FATAL, (errcode_for_file_access(), errmsg("could not rename file \"%s\" to \"%s\": %m", RECOVERY_COMMAND_FILE, RECOVERY_COMMAND_DONE))); ereport(LOG, (errmsg("archive recovery complete"))); } /* * For point-in-time recovery, this function decides whether we want to * stop applying the XLOG at or after the current record. * * Returns TRUE if we are stopping, FALSE otherwise. On TRUE return, * *includeThis is set TRUE if we should apply this record before stopping. * * We also track the timestamp of the latest applied COMMIT/ABORT * record in XLogCtl->recoveryLastXTime, for logging purposes. * Also, some information is saved in recoveryStopXid et al for use in * annotating the new timeline's history file. */ static bool recoveryStopsHere(XLogRecord *record, bool *includeThis) { bool stopsHere; uint8 record_info; TimestampTz recordXtime; char recordRPName[MAXFNAMELEN]; /* We only consider stopping at COMMIT, ABORT or RESTORE POINT records */ if (record->xl_rmid != RM_XACT_ID && record->xl_rmid != RM_XLOG_ID) return false; record_info = record->xl_info & ~XLR_INFO_MASK; if (record->xl_rmid == RM_XACT_ID && record_info == XLOG_XACT_COMMIT_COMPACT) { xl_xact_commit_compact *recordXactCommitData; recordXactCommitData = (xl_xact_commit_compact *) XLogRecGetData(record); recordXtime = recordXactCommitData->xact_time; } else if (record->xl_rmid == RM_XACT_ID && record_info == XLOG_XACT_COMMIT) { xl_xact_commit *recordXactCommitData; recordXactCommitData = (xl_xact_commit *) XLogRecGetData(record); recordXtime = recordXactCommitData->xact_time; } else if (record->xl_rmid == RM_XACT_ID && record_info == XLOG_XACT_ABORT) { xl_xact_abort *recordXactAbortData; recordXactAbortData = (xl_xact_abort *) XLogRecGetData(record); recordXtime = recordXactAbortData->xact_time; } else if (record->xl_rmid == RM_XLOG_ID && record_info == XLOG_RESTORE_POINT) { xl_restore_point *recordRestorePointData; recordRestorePointData = (xl_restore_point *) XLogRecGetData(record); recordXtime = recordRestorePointData->rp_time; strncpy(recordRPName, recordRestorePointData->rp_name, MAXFNAMELEN); } else return false; /* Do we have a PITR target at all? */ if (recoveryTarget == RECOVERY_TARGET_UNSET) { /* * Save timestamp of latest transaction commit/abort if this is a * transaction record */ if (record->xl_rmid == RM_XACT_ID) SetLatestXTime(recordXtime); return false; } if (recoveryTarget == RECOVERY_TARGET_XID) { /* * There can be only one transaction end record with this exact * transactionid * * when testing for an xid, we MUST test for equality only, since * transactions are numbered in the order they start, not the order * they complete. A higher numbered xid will complete before you about * 50% of the time... */ stopsHere = (record->xl_xid == recoveryTargetXid); if (stopsHere) *includeThis = recoveryTargetInclusive; } else if (recoveryTarget == RECOVERY_TARGET_NAME) { /* * There can be many restore points that share the same name, so we * stop at the first one */ stopsHere = (strcmp(recordRPName, recoveryTargetName) == 0); /* * Ignore recoveryTargetInclusive because this is not a transaction * record */ *includeThis = false; } else { /* * There can be many transactions that share the same commit time, so * we stop after the last one, if we are inclusive, or stop at the * first one if we are exclusive */ if (recoveryTargetInclusive) stopsHere = (recordXtime > recoveryTargetTime); else stopsHere = (recordXtime >= recoveryTargetTime); if (stopsHere) *includeThis = false; } if (stopsHere) { recoveryStopXid = record->xl_xid; recoveryStopTime = recordXtime; recoveryStopAfter = *includeThis; if (record_info == XLOG_XACT_COMMIT_COMPACT || record_info == XLOG_XACT_COMMIT) { if (recoveryStopAfter) ereport(LOG, (errmsg("recovery stopping after commit of transaction %u, time %s", recoveryStopXid, timestamptz_to_str(recoveryStopTime)))); else ereport(LOG, (errmsg("recovery stopping before commit of transaction %u, time %s", recoveryStopXid, timestamptz_to_str(recoveryStopTime)))); } else if (record_info == XLOG_XACT_ABORT) { if (recoveryStopAfter) ereport(LOG, (errmsg("recovery stopping after abort of transaction %u, time %s", recoveryStopXid, timestamptz_to_str(recoveryStopTime)))); else ereport(LOG, (errmsg("recovery stopping before abort of transaction %u, time %s", recoveryStopXid, timestamptz_to_str(recoveryStopTime)))); } else { strncpy(recoveryStopName, recordRPName, MAXFNAMELEN); ereport(LOG, (errmsg("recovery stopping at restore point \"%s\", time %s", recoveryStopName, timestamptz_to_str(recoveryStopTime)))); } /* * Note that if we use a RECOVERY_TARGET_TIME then we can stop at a * restore point since they are timestamped, though the latest * transaction time is not updated. */ if (record->xl_rmid == RM_XACT_ID && recoveryStopAfter) SetLatestXTime(recordXtime); } else if (record->xl_rmid == RM_XACT_ID) SetLatestXTime(recordXtime); return stopsHere; } /* * Recheck shared recoveryPause by polling. * * XXX Can also be done with shared latch. */ static void recoveryPausesHere(void) { ereport(LOG, (errmsg("recovery has paused"), errhint("Execute pg_xlog_replay_resume() to continue."))); while (RecoveryIsPaused()) { pg_usleep(1000000L); /* 1000 ms */ HandleStartupProcInterrupts(); } } bool RecoveryIsPaused(void) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; bool recoveryPause; SpinLockAcquire(&xlogctl->info_lck); recoveryPause = xlogctl->recoveryPause; SpinLockRelease(&xlogctl->info_lck); return recoveryPause; } void SetRecoveryPause(bool recoveryPause) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); xlogctl->recoveryPause = recoveryPause; SpinLockRelease(&xlogctl->info_lck); } /* * Save timestamp of latest processed commit/abort record. * * We keep this in XLogCtl, not a simple static variable, so that it can be * seen by processes other than the startup process. Note in particular * that CreateRestartPoint is executed in the checkpointer. */ static void SetLatestXTime(TimestampTz xtime) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); xlogctl->recoveryLastXTime = xtime; SpinLockRelease(&xlogctl->info_lck); } /* * Fetch timestamp of latest processed commit/abort record. */ TimestampTz GetLatestXTime(void) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; TimestampTz xtime; SpinLockAcquire(&xlogctl->info_lck); xtime = xlogctl->recoveryLastXTime; SpinLockRelease(&xlogctl->info_lck); return xtime; } /* * Save timestamp of the next chunk of WAL records to apply. * * We keep this in XLogCtl, not a simple static variable, so that it can be * seen by all backends. */ static void SetCurrentChunkStartTime(TimestampTz xtime) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); xlogctl->currentChunkStartTime = xtime; SpinLockRelease(&xlogctl->info_lck); } /* * Fetch timestamp of latest processed commit/abort record. * Startup process maintains an accurate local copy in XLogReceiptTime */ TimestampTz GetCurrentChunkReplayStartTime(void) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; TimestampTz xtime; SpinLockAcquire(&xlogctl->info_lck); xtime = xlogctl->currentChunkStartTime; SpinLockRelease(&xlogctl->info_lck); return xtime; } /* * Returns time of receipt of current chunk of XLOG data, as well as * whether it was received from streaming replication or from archives. */ void GetXLogReceiptTime(TimestampTz *rtime, bool *fromStream) { /* * This must be executed in the startup process, since we don't export the * relevant state to shared memory. */ Assert(InRecovery); *rtime = XLogReceiptTime; *fromStream = (XLogReceiptSource == XLOG_FROM_STREAM); } /* * Note that text field supplied is a parameter name and does not require * translation */ #define RecoveryRequiresIntParameter(param_name, currValue, minValue) \ do { \ if (currValue < minValue) \ ereport(ERROR, \ (errmsg("hot standby is not possible because " \ "%s = %d is a lower setting than on the master server " \ "(its value was %d)", \ param_name, \ currValue, \ minValue))); \ } while(0) /* * Check to see if required parameters are set high enough on this server * for various aspects of recovery operation. */ static void CheckRequiredParameterValues(void) { /* * For archive recovery, the WAL must be generated with at least 'archive' * wal_level. */ if (InArchiveRecovery && ControlFile->wal_level == WAL_LEVEL_MINIMAL) { ereport(WARNING, (errmsg("WAL was generated with wal_level=minimal, data may be missing"), errhint("This happens if you temporarily set wal_level=minimal without taking a new base backup."))); } /* * For Hot Standby, the WAL must be generated with 'hot_standby' mode, and * we must have at least as many backend slots as the primary. */ if (InArchiveRecovery && EnableHotStandby) { if (ControlFile->wal_level < WAL_LEVEL_HOT_STANDBY) ereport(ERROR, (errmsg("hot standby is not possible because wal_level was not set to \"hot_standby\" on the master server"), errhint("Either set wal_level to \"hot_standby\" on the master, or turn off hot_standby here."))); /* We ignore autovacuum_max_workers when we make this test. */ RecoveryRequiresIntParameter("max_connections", MaxConnections, ControlFile->MaxConnections); RecoveryRequiresIntParameter("max_prepared_xacts", max_prepared_xacts, ControlFile->max_prepared_xacts); RecoveryRequiresIntParameter("max_locks_per_xact", max_locks_per_xact, ControlFile->max_locks_per_xact); } } /* * This must be called ONCE during postmaster or standalone-backend startup */ void StartupXLOG(void) { XLogCtlInsert *Insert; CheckPoint checkPoint; bool wasShutdown; bool reachedStopPoint = false; bool haveBackupLabel = false; XLogRecPtr RecPtr, checkPointLoc, EndOfLog; uint32 endLogId; uint32 endLogSeg; XLogRecord *record; uint32 freespace; TransactionId oldestActiveXID; bool backupEndRequired = false; bool backupFromStandby = false; DBState dbstate_at_startup; /* * Read control file and check XLOG status looks valid. * * Note: in most control paths, *ControlFile is already valid and we need * not do ReadControlFile() here, but might as well do it to be sure. */ ReadControlFile(); if (ControlFile->state < DB_SHUTDOWNED || ControlFile->state > DB_IN_PRODUCTION || !XRecOffIsValid(ControlFile->checkPoint.xrecoff)) ereport(FATAL, (errmsg("control file contains invalid data"))); if (ControlFile->state == DB_SHUTDOWNED) ereport(LOG, (errmsg("database system was shut down at %s", str_time(ControlFile->time)))); else if (ControlFile->state == DB_SHUTDOWNED_IN_RECOVERY) ereport(LOG, (errmsg("database system was shut down in recovery at %s", str_time(ControlFile->time)))); else if (ControlFile->state == DB_SHUTDOWNING) ereport(LOG, (errmsg("database system shutdown was interrupted; last known up at %s", str_time(ControlFile->time)))); else if (ControlFile->state == DB_IN_CRASH_RECOVERY) ereport(LOG, (errmsg("database system was interrupted while in recovery at %s", str_time(ControlFile->time)), errhint("This probably means that some data is corrupted and" " you will have to use the last backup for recovery."))); else if (ControlFile->state == DB_IN_ARCHIVE_RECOVERY) ereport(LOG, (errmsg("database system was interrupted while in recovery at log time %s", str_time(ControlFile->checkPointCopy.time)), errhint("If this has occurred more than once some data might be corrupted" " and you might need to choose an earlier recovery target."))); else if (ControlFile->state == DB_IN_PRODUCTION) ereport(LOG, (errmsg("database system was interrupted; last known up at %s", str_time(ControlFile->time)))); /* This is just to allow attaching to startup process with a debugger */ #ifdef XLOG_REPLAY_DELAY if (ControlFile->state != DB_SHUTDOWNED) pg_usleep(60000000L); #endif /* * Verify that pg_xlog and pg_xlog/archive_status exist. In cases where * someone has performed a copy for PITR, these directories may have been * excluded and need to be re-created. */ ValidateXLOGDirectoryStructure(); /* * Clear out any old relcache cache files. This is *necessary* if we do * any WAL replay, since that would probably result in the cache files * being out of sync with database reality. In theory we could leave them * in place if the database had been cleanly shut down, but it seems * safest to just remove them always and let them be rebuilt during the * first backend startup. */ RelationCacheInitFileRemove(); /* * Initialize on the assumption we want to recover to the same timeline * that's active according to pg_control. */ recoveryTargetTLI = ControlFile->checkPointCopy.ThisTimeLineID; /* * Check for recovery control file, and if so set up state for offline * recovery */ readRecoveryCommandFile(); /* Now we can determine the list of expected TLIs */ expectedTLIs = readTimeLineHistory(recoveryTargetTLI); /* * If pg_control's timeline is not in expectedTLIs, then we cannot * proceed: the backup is not part of the history of the requested * timeline. */ if (!list_member_int(expectedTLIs, (int) ControlFile->checkPointCopy.ThisTimeLineID)) ereport(FATAL, (errmsg("requested timeline %u is not a child of database system timeline %u", recoveryTargetTLI, ControlFile->checkPointCopy.ThisTimeLineID))); /* * Save the selected recovery target timeline ID and * archive_cleanup_command in shared memory so that other processes can * see them */ XLogCtl->RecoveryTargetTLI = recoveryTargetTLI; strncpy(XLogCtl->archiveCleanupCommand, archiveCleanupCommand ? archiveCleanupCommand : "", sizeof(XLogCtl->archiveCleanupCommand)); if (InArchiveRecovery) { if (StandbyMode) ereport(LOG, (errmsg("entering standby mode"))); else if (recoveryTarget == RECOVERY_TARGET_XID) ereport(LOG, (errmsg("starting point-in-time recovery to XID %u", recoveryTargetXid))); else if (recoveryTarget == RECOVERY_TARGET_TIME) ereport(LOG, (errmsg("starting point-in-time recovery to %s", timestamptz_to_str(recoveryTargetTime)))); else if (recoveryTarget == RECOVERY_TARGET_NAME) ereport(LOG, (errmsg("starting point-in-time recovery to \"%s\"", recoveryTargetName))); else ereport(LOG, (errmsg("starting archive recovery"))); } /* * Take ownership of the wakeup latch if we're going to sleep during * recovery. */ if (StandbyMode) OwnLatch(&XLogCtl->recoveryWakeupLatch); if (read_backup_label(&checkPointLoc, &backupEndRequired, &backupFromStandby)) { /* * When a backup_label file is present, we want to roll forward from * the checkpoint it identifies, rather than using pg_control. */ record = ReadCheckpointRecord(checkPointLoc, 0); if (record != NULL) { memcpy(&checkPoint, XLogRecGetData(record), sizeof(CheckPoint)); wasShutdown = (record->xl_info == XLOG_CHECKPOINT_SHUTDOWN); ereport(DEBUG1, (errmsg("checkpoint record is at %X/%X", checkPointLoc.xlogid, checkPointLoc.xrecoff))); InRecovery = true; /* force recovery even if SHUTDOWNED */ /* * Make sure that REDO location exists. This may not be the case * if there was a crash during an online backup, which left a * backup_label around that references a WAL segment that's * already been archived. */ if (XLByteLT(checkPoint.redo, checkPointLoc)) { if (!ReadRecord(&(checkPoint.redo), LOG, false)) ereport(FATAL, (errmsg("could not find redo location referenced by checkpoint record"), errhint("If you are not restoring from a backup, try removing the file \"%s/backup_label\".", DataDir))); } } else { ereport(FATAL, (errmsg("could not locate required checkpoint record"), errhint("If you are not restoring from a backup, try removing the file \"%s/backup_label\".", DataDir))); wasShutdown = false; /* keep compiler quiet */ } /* set flag to delete it later */ haveBackupLabel = true; } else { /* * Get the last valid checkpoint record. If the latest one according * to pg_control is broken, try the next-to-last one. */ checkPointLoc = ControlFile->checkPoint; RedoStartLSN = ControlFile->checkPointCopy.redo; record = ReadCheckpointRecord(checkPointLoc, 1); if (record != NULL) { ereport(DEBUG1, (errmsg("checkpoint record is at %X/%X", checkPointLoc.xlogid, checkPointLoc.xrecoff))); } else if (StandbyMode) { /* * The last valid checkpoint record required for a streaming * recovery exists in neither standby nor the primary. */ ereport(PANIC, (errmsg("could not locate a valid checkpoint record"))); } else { checkPointLoc = ControlFile->prevCheckPoint; record = ReadCheckpointRecord(checkPointLoc, 2); if (record != NULL) { ereport(LOG, (errmsg("using previous checkpoint record at %X/%X", checkPointLoc.xlogid, checkPointLoc.xrecoff))); InRecovery = true; /* force recovery even if SHUTDOWNED */ } else ereport(PANIC, (errmsg("could not locate a valid checkpoint record"))); } memcpy(&checkPoint, XLogRecGetData(record), sizeof(CheckPoint)); wasShutdown = (record->xl_info == XLOG_CHECKPOINT_SHUTDOWN); } LastRec = RecPtr = checkPointLoc; ereport(DEBUG1, (errmsg("redo record is at %X/%X; shutdown %s", checkPoint.redo.xlogid, checkPoint.redo.xrecoff, wasShutdown ? "TRUE" : "FALSE"))); ereport(DEBUG1, (errmsg("next transaction ID: %u/%u; next OID: %u", checkPoint.nextXidEpoch, checkPoint.nextXid, checkPoint.nextOid))); ereport(DEBUG1, (errmsg("next MultiXactId: %u; next MultiXactOffset: %u", checkPoint.nextMulti, checkPoint.nextMultiOffset))); ereport(DEBUG1, (errmsg("oldest unfrozen transaction ID: %u, in database %u", checkPoint.oldestXid, checkPoint.oldestXidDB))); if (!TransactionIdIsNormal(checkPoint.nextXid)) ereport(PANIC, (errmsg("invalid next transaction ID"))); ShmemVariableCache->nextXid = checkPoint.nextXid; ShmemVariableCache->nextOid = checkPoint.nextOid; ShmemVariableCache->oidCount = 0; MultiXactSetNextMXact(checkPoint.nextMulti, checkPoint.nextMultiOffset); SetTransactionIdLimit(checkPoint.oldestXid, checkPoint.oldestXidDB); /* * We must replay WAL entries using the same TimeLineID they were created * under, so temporarily adopt the TLI indicated by the checkpoint (see * also xlog_redo()). */ ThisTimeLineID = checkPoint.ThisTimeLineID; lastFullPageWrites = checkPoint.fullPageWrites; RedoRecPtr = XLogCtl->Insert.RedoRecPtr = checkPoint.redo; if (XLByteLT(RecPtr, checkPoint.redo)) ereport(PANIC, (errmsg("invalid redo in checkpoint record"))); /* * Check whether we need to force recovery from WAL. If it appears to * have been a clean shutdown and we did not have a recovery.conf file, * then assume no recovery needed. */ if (XLByteLT(checkPoint.redo, RecPtr)) { if (wasShutdown) ereport(PANIC, (errmsg("invalid redo record in shutdown checkpoint"))); InRecovery = true; } else if (ControlFile->state != DB_SHUTDOWNED) InRecovery = true; else if (InArchiveRecovery) { /* force recovery due to presence of recovery.conf */ InRecovery = true; } /* REDO */ if (InRecovery) { int rmid; /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; /* * Update pg_control to show that we are recovering and to show the * selected checkpoint as the place we are starting from. We also mark * pg_control with any minimum recovery stop point obtained from a * backup history file. */ dbstate_at_startup = ControlFile->state; if (InArchiveRecovery) ControlFile->state = DB_IN_ARCHIVE_RECOVERY; else { ereport(LOG, (errmsg("database system was not properly shut down; " "automatic recovery in progress"))); ControlFile->state = DB_IN_CRASH_RECOVERY; } ControlFile->prevCheckPoint = ControlFile->checkPoint; ControlFile->checkPoint = checkPointLoc; ControlFile->checkPointCopy = checkPoint; if (InArchiveRecovery) { /* initialize minRecoveryPoint if not set yet */ if (XLByteLT(ControlFile->minRecoveryPoint, checkPoint.redo)) ControlFile->minRecoveryPoint = checkPoint.redo; } /* * Set backupStartPoint if we're starting recovery from a base backup. * * Set backupEndPoint and use minRecoveryPoint as the backup end * location if we're starting recovery from a base backup which was * taken from the standby. In this case, the database system status in * pg_control must indicate DB_IN_ARCHIVE_RECOVERY. If not, which * means that backup is corrupted, so we cancel recovery. */ if (haveBackupLabel) { ControlFile->backupStartPoint = checkPoint.redo; ControlFile->backupEndRequired = backupEndRequired; if (backupFromStandby) { if (dbstate_at_startup != DB_IN_ARCHIVE_RECOVERY) ereport(FATAL, (errmsg("backup_label contains inconsistent data with control file"), errhint("This means that the backup is corrupted and you will " "have to use another backup for recovery."))); ControlFile->backupEndPoint = ControlFile->minRecoveryPoint; } } ControlFile->time = (pg_time_t) time(NULL); /* No need to hold ControlFileLock yet, we aren't up far enough */ UpdateControlFile(); /* initialize shared-memory copy of latest checkpoint XID/epoch */ XLogCtl->ckptXidEpoch = ControlFile->checkPointCopy.nextXidEpoch; XLogCtl->ckptXid = ControlFile->checkPointCopy.nextXid; /* initialize our local copy of minRecoveryPoint */ minRecoveryPoint = ControlFile->minRecoveryPoint; /* * Reset pgstat data, because it may be invalid after recovery. */ pgstat_reset_all(); /* * If there was a backup label file, it's done its job and the info * has now been propagated into pg_control. We must get rid of the * label file so that if we crash during recovery, we'll pick up at * the latest recovery restartpoint instead of going all the way back * to the backup start point. It seems prudent though to just rename * the file out of the way rather than delete it completely. */ if (haveBackupLabel) { unlink(BACKUP_LABEL_OLD); if (rename(BACKUP_LABEL_FILE, BACKUP_LABEL_OLD) != 0) ereport(FATAL, (errcode_for_file_access(), errmsg("could not rename file \"%s\" to \"%s\": %m", BACKUP_LABEL_FILE, BACKUP_LABEL_OLD))); } /* Check that the GUCs used to generate the WAL allow recovery */ CheckRequiredParameterValues(); /* * We're in recovery, so unlogged relations may be trashed and must be * reset. This should be done BEFORE allowing Hot Standby * connections, so that read-only backends don't try to read whatever * garbage is left over from before. */ ResetUnloggedRelations(UNLOGGED_RELATION_CLEANUP); /* * Likewise, delete any saved transaction snapshot files that got left * behind by crashed backends. */ DeleteAllExportedSnapshotFiles(); /* * Initialize for Hot Standby, if enabled. We won't let backends in * yet, not until we've reached the min recovery point specified in * control file and we've established a recovery snapshot from a * running-xacts WAL record. */ if (InArchiveRecovery && EnableHotStandby) { TransactionId *xids; int nxids; ereport(DEBUG1, (errmsg("initializing for hot standby"))); InitRecoveryTransactionEnvironment(); if (wasShutdown) oldestActiveXID = PrescanPreparedTransactions(&xids, &nxids); else oldestActiveXID = checkPoint.oldestActiveXid; Assert(TransactionIdIsValid(oldestActiveXID)); /* * Startup commit log and subtrans only. Other SLRUs are not * maintained during recovery and need not be started yet. */ StartupCLOG(); StartupSUBTRANS(oldestActiveXID); /* * If we're beginning at a shutdown checkpoint, we know that * nothing was running on the master at this point. So fake-up an * empty running-xacts record and use that here and now. Recover * additional standby state for prepared transactions. */ if (wasShutdown) { RunningTransactionsData running; TransactionId latestCompletedXid; /* * Construct a RunningTransactions snapshot representing a * shut down server, with only prepared transactions still * alive. We're never overflowed at this point because all * subxids are listed with their parent prepared transactions. */ running.xcnt = nxids; running.subxid_overflow = false; running.nextXid = checkPoint.nextXid; running.oldestRunningXid = oldestActiveXID; latestCompletedXid = checkPoint.nextXid; TransactionIdRetreat(latestCompletedXid); Assert(TransactionIdIsNormal(latestCompletedXid)); running.latestCompletedXid = latestCompletedXid; running.xids = xids; ProcArrayApplyRecoveryInfo(&running); StandbyRecoverPreparedTransactions(false); } } /* Initialize resource managers */ for (rmid = 0; rmid <= RM_MAX_ID; rmid++) { if (RmgrTable[rmid].rm_startup != NULL) RmgrTable[rmid].rm_startup(); } /* * Initialize shared replayEndRecPtr, recoveryLastRecPtr, and * recoveryLastXTime. * * This is slightly confusing if we're starting from an online * checkpoint; we've just read and replayed the chekpoint record, but * we're going to start replay from its redo pointer, which precedes * the location of the checkpoint record itself. So even though the * last record we've replayed is indeed ReadRecPtr, we haven't * replayed all the preceding records yet. That's OK for the current * use of these variables. */ SpinLockAcquire(&xlogctl->info_lck); xlogctl->replayEndRecPtr = ReadRecPtr; xlogctl->recoveryLastRecPtr = EndRecPtr; xlogctl->recoveryLastXTime = 0; xlogctl->currentChunkStartTime = 0; xlogctl->recoveryPause = false; SpinLockRelease(&xlogctl->info_lck); /* Also ensure XLogReceiptTime has a sane value */ XLogReceiptTime = GetCurrentTimestamp(); /* * Let postmaster know we've started redo now, so that it can launch * checkpointer to perform restartpoints. We don't bother during * crash recovery as restartpoints can only be performed during * archive recovery. And we'd like to keep crash recovery simple, to * avoid introducing bugs that could affect you when recovering after * crash. * * After this point, we can no longer assume that we're the only * process in addition to postmaster! Also, fsync requests are * subsequently to be handled by the checkpointer, not locally. */ if (InArchiveRecovery && IsUnderPostmaster) { PublishStartupProcessInformation(); SetForwardFsyncRequests(); SendPostmasterSignal(PMSIGNAL_RECOVERY_STARTED); bgwriterLaunched = true; } /* * Allow read-only connections immediately if we're consistent * already. */ CheckRecoveryConsistency(); /* * Find the first record that logically follows the checkpoint --- it * might physically precede it, though. */ if (XLByteLT(checkPoint.redo, RecPtr)) { /* back up to find the record */ record = ReadRecord(&(checkPoint.redo), PANIC, false); } else { /* just have to read next record after CheckPoint */ record = ReadRecord(NULL, LOG, false); } if (record != NULL) { bool recoveryContinue = true; bool recoveryApply = true; bool recoveryPause = false; ErrorContextCallback errcontext; TimestampTz xtime; InRedo = true; ereport(LOG, (errmsg("redo starts at %X/%X", ReadRecPtr.xlogid, ReadRecPtr.xrecoff))); /* * main redo apply loop */ do { #ifdef WAL_DEBUG if (XLOG_DEBUG || (rmid == RM_XACT_ID && trace_recovery_messages <= DEBUG2) || (rmid != RM_XACT_ID && trace_recovery_messages <= DEBUG3)) { StringInfoData buf; initStringInfo(&buf); appendStringInfo(&buf, "REDO @ %X/%X; LSN %X/%X: ", ReadRecPtr.xlogid, ReadRecPtr.xrecoff, EndRecPtr.xlogid, EndRecPtr.xrecoff); xlog_outrec(&buf, record); appendStringInfo(&buf, " - "); RmgrTable[record->xl_rmid].rm_desc(&buf, record->xl_info, XLogRecGetData(record)); elog(LOG, "%s", buf.data); pfree(buf.data); } #endif /* Handle interrupt signals of startup process */ HandleStartupProcInterrupts(); /* Allow read-only connections if we're consistent now */ CheckRecoveryConsistency(); /* * Have we reached our recovery target? */ if (recoveryStopsHere(record, &recoveryApply)) { /* * Pause only if users can connect to send a resume * message */ if (recoveryPauseAtTarget && standbyState == STANDBY_SNAPSHOT_READY) { SetRecoveryPause(true); recoveryPausesHere(); } reachedStopPoint = true; /* see below */ recoveryContinue = false; if (!recoveryApply) break; } /* Setup error traceback support for ereport() */ errcontext.callback = rm_redo_error_callback; errcontext.arg = (void *) record; errcontext.previous = error_context_stack; error_context_stack = &errcontext; /* * ShmemVariableCache->nextXid must be beyond record's xid. * * We don't expect anyone else to modify nextXid, hence we * don't need to hold a lock while examining it. We still * acquire the lock to modify it, though. */ if (TransactionIdFollowsOrEquals(record->xl_xid, ShmemVariableCache->nextXid)) { LWLockAcquire(XidGenLock, LW_EXCLUSIVE); ShmemVariableCache->nextXid = record->xl_xid; TransactionIdAdvance(ShmemVariableCache->nextXid); LWLockRelease(XidGenLock); } /* * Update shared replayEndRecPtr before replaying this record, * so that XLogFlush will update minRecoveryPoint correctly. */ SpinLockAcquire(&xlogctl->info_lck); xlogctl->replayEndRecPtr = EndRecPtr; recoveryPause = xlogctl->recoveryPause; SpinLockRelease(&xlogctl->info_lck); /* * Pause only if users can connect to send a resume message */ if (recoveryPause && standbyState == STANDBY_SNAPSHOT_READY) recoveryPausesHere(); /* * If we are attempting to enter Hot Standby mode, process * XIDs we see */ if (standbyState >= STANDBY_INITIALIZED && TransactionIdIsValid(record->xl_xid)) RecordKnownAssignedTransactionIds(record->xl_xid); /* Now apply the WAL record itself */ RmgrTable[record->xl_rmid].rm_redo(EndRecPtr, record); /* Pop the error context stack */ error_context_stack = errcontext.previous; if (!XLogRecPtrIsInvalid(ControlFile->backupStartPoint) && XLByteLE(ControlFile->backupEndPoint, EndRecPtr)) { /* * We have reached the end of base backup, the point where * the minimum recovery point in pg_control indicates. The * data on disk is now consistent. Reset backupStartPoint * and backupEndPoint. */ elog(DEBUG1, "end of backup reached"); LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); MemSet(&ControlFile->backupStartPoint, 0, sizeof(XLogRecPtr)); MemSet(&ControlFile->backupEndPoint, 0, sizeof(XLogRecPtr)); ControlFile->backupEndRequired = false; UpdateControlFile(); LWLockRelease(ControlFileLock); } /* * Update shared recoveryLastRecPtr after this record has been * replayed. */ SpinLockAcquire(&xlogctl->info_lck); xlogctl->recoveryLastRecPtr = EndRecPtr; SpinLockRelease(&xlogctl->info_lck); LastRec = ReadRecPtr; record = ReadRecord(NULL, LOG, false); } while (record != NULL && recoveryContinue); /* * end of main redo apply loop */ ereport(LOG, (errmsg("redo done at %X/%X", ReadRecPtr.xlogid, ReadRecPtr.xrecoff))); xtime = GetLatestXTime(); if (xtime) ereport(LOG, (errmsg("last completed transaction was at log time %s", timestamptz_to_str(xtime)))); InRedo = false; } else { /* there are no WAL records following the checkpoint */ ereport(LOG, (errmsg("redo is not required"))); } } /* * Kill WAL receiver, if it's still running, before we continue to write * the startup checkpoint record. It will trump over the checkpoint and * subsequent records if it's still alive when we start writing WAL. */ ShutdownWalRcv(); /* * We don't need the latch anymore. It's not strictly necessary to disown * it, but let's do it for the sake of tidiness. */ if (StandbyMode) DisownLatch(&XLogCtl->recoveryWakeupLatch); /* * We are now done reading the xlog from stream. Turn off streaming * recovery to force fetching the files (which would be required at end of * recovery, e.g., timeline history file) from archive or pg_xlog. */ StandbyMode = false; /* * Re-fetch the last valid or last applied record, so we can identify the * exact endpoint of what we consider the valid portion of WAL. */ record = ReadRecord(&LastRec, PANIC, false); EndOfLog = EndRecPtr; XLByteToPrevSeg(EndOfLog, endLogId, endLogSeg); /* * Complain if we did not roll forward far enough to render the backup * dump consistent. Note: it is indeed okay to look at the local variable * minRecoveryPoint here, even though ControlFile->minRecoveryPoint might * be further ahead --- ControlFile->minRecoveryPoint cannot have been * advanced beyond the WAL we processed. */ if (InRecovery && (XLByteLT(EndOfLog, minRecoveryPoint) || !XLogRecPtrIsInvalid(ControlFile->backupStartPoint))) { if (reachedStopPoint) { /* stopped because of stop request */ ereport(FATAL, (errmsg("requested recovery stop point is before consistent recovery point"))); } /* * Ran off end of WAL before reaching end-of-backup WAL record, or * minRecoveryPoint. That's usually a bad sign, indicating that you * tried to recover from an online backup but never called * pg_stop_backup(), or you didn't archive all the WAL up to that * point. However, this also happens in crash recovery, if the system * crashes while an online backup is in progress. We must not treat * that as an error, or the database will refuse to start up. */ if (InArchiveRecovery || ControlFile->backupEndRequired) { if (ControlFile->backupEndRequired) ereport(FATAL, (errmsg("WAL ends before end of online backup"), errhint("All WAL generated while online backup was taken must be available at recovery."))); else if (!XLogRecPtrIsInvalid(ControlFile->backupStartPoint)) ereport(FATAL, (errmsg("WAL ends before end of online backup"), errhint("Online backup started with pg_start_backup() must be ended with pg_stop_backup(), and all WAL up to that point must be available at recovery."))); else ereport(FATAL, (errmsg("WAL ends before consistent recovery point"))); } } /* * Consider whether we need to assign a new timeline ID. * * If we are doing an archive recovery, we always assign a new ID. This * handles a couple of issues. If we stopped short of the end of WAL * during recovery, then we are clearly generating a new timeline and must * assign it a unique new ID. Even if we ran to the end, modifying the * current last segment is problematic because it may result in trying to * overwrite an already-archived copy of that segment, and we encourage * DBAs to make their archive_commands reject that. We can dodge the * problem by making the new active segment have a new timeline ID. * * In a normal crash recovery, we can just extend the timeline we were in. */ if (InArchiveRecovery) { ThisTimeLineID = findNewestTimeLine(recoveryTargetTLI) + 1; ereport(LOG, (errmsg("selected new timeline ID: %u", ThisTimeLineID))); writeTimeLineHistory(ThisTimeLineID, recoveryTargetTLI, curFileTLI, endLogId, endLogSeg); } /* Save the selected TimeLineID in shared memory, too */ XLogCtl->ThisTimeLineID = ThisTimeLineID; /* * We are now done reading the old WAL. Turn off archive fetching if it * was active, and make a writable copy of the last WAL segment. (Note * that we also have a copy of the last block of the old WAL in readBuf; * we will use that below.) */ if (InArchiveRecovery) exitArchiveRecovery(curFileTLI, endLogId, endLogSeg); /* * Prepare to write WAL starting at EndOfLog position, and init xlog * buffer cache using the block containing the last record from the * previous incarnation. */ openLogId = endLogId; openLogSeg = endLogSeg; openLogFile = XLogFileOpen(openLogId, openLogSeg); openLogOff = 0; Insert = &XLogCtl->Insert; Insert->PrevRecord = LastRec; XLogCtl->xlblocks[0].xlogid = openLogId; XLogCtl->xlblocks[0].xrecoff = ((EndOfLog.xrecoff - 1) / XLOG_BLCKSZ + 1) * XLOG_BLCKSZ; /* * Tricky point here: readBuf contains the *last* block that the LastRec * record spans, not the one it starts in. The last block is indeed the * one we want to use. */ Assert(readOff == (XLogCtl->xlblocks[0].xrecoff - XLOG_BLCKSZ) % XLogSegSize); memcpy((char *) Insert->currpage, readBuf, XLOG_BLCKSZ); Insert->currpos = (char *) Insert->currpage + (EndOfLog.xrecoff + XLOG_BLCKSZ - XLogCtl->xlblocks[0].xrecoff); LogwrtResult.Write = LogwrtResult.Flush = EndOfLog; XLogCtl->LogwrtResult = LogwrtResult; XLogCtl->LogwrtRqst.Write = EndOfLog; XLogCtl->LogwrtRqst.Flush = EndOfLog; freespace = INSERT_FREESPACE(Insert); if (freespace > 0) { /* Make sure rest of page is zero */ MemSet(Insert->currpos, 0, freespace); XLogCtl->Write.curridx = 0; } else { /* * Whenever LogwrtResult points to exactly the end of a page, * Write.curridx must point to the *next* page (see XLogWrite()). * * Note: it might seem we should do AdvanceXLInsertBuffer() here, but * this is sufficient. The first actual attempt to insert a log * record will advance the insert state. */ XLogCtl->Write.curridx = NextBufIdx(0); } /* Pre-scan prepared transactions to find out the range of XIDs present */ oldestActiveXID = PrescanPreparedTransactions(NULL, NULL); /* * Update full_page_writes in shared memory and write an XLOG_FPW_CHANGE * record before resource manager writes cleanup WAL records or checkpoint * record is written. */ Insert->fullPageWrites = lastFullPageWrites; LocalSetXLogInsertAllowed(); UpdateFullPageWrites(); LocalXLogInsertAllowed = -1; if (InRecovery) { int rmid; /* * Resource managers might need to write WAL records, eg, to record * index cleanup actions. So temporarily enable XLogInsertAllowed in * this process only. */ LocalSetXLogInsertAllowed(); /* * Allow resource managers to do any required cleanup. */ for (rmid = 0; rmid <= RM_MAX_ID; rmid++) { if (RmgrTable[rmid].rm_cleanup != NULL) RmgrTable[rmid].rm_cleanup(); } /* Disallow XLogInsert again */ LocalXLogInsertAllowed = -1; /* * Perform a checkpoint to update all our recovery activity to disk. * * Note that we write a shutdown checkpoint rather than an on-line * one. This is not particularly critical, but since we may be * assigning a new TLI, using a shutdown checkpoint allows us to have * the rule that TLI only changes in shutdown checkpoints, which * allows some extra error checking in xlog_redo. */ if (bgwriterLaunched) RequestCheckpoint(CHECKPOINT_END_OF_RECOVERY | CHECKPOINT_IMMEDIATE | CHECKPOINT_WAIT); else CreateCheckPoint(CHECKPOINT_END_OF_RECOVERY | CHECKPOINT_IMMEDIATE); /* * And finally, execute the recovery_end_command, if any. */ if (recoveryEndCommand) ExecuteRecoveryCommand(recoveryEndCommand, "recovery_end_command", true); } /* * Preallocate additional log files, if wanted. */ PreallocXlogFiles(EndOfLog); /* * Reset initial contents of unlogged relations. This has to be done * AFTER recovery is complete so that any unlogged relations created * during recovery also get picked up. */ if (InRecovery) ResetUnloggedRelations(UNLOGGED_RELATION_INIT); /* * Okay, we're officially UP. */ InRecovery = false; LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); ControlFile->state = DB_IN_PRODUCTION; ControlFile->time = (pg_time_t) time(NULL); UpdateControlFile(); LWLockRelease(ControlFileLock); /* start the archive_timeout timer running */ XLogCtl->Write.lastSegSwitchTime = (pg_time_t) time(NULL); /* also initialize latestCompletedXid, to nextXid - 1 */ LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE); ShmemVariableCache->latestCompletedXid = ShmemVariableCache->nextXid; TransactionIdRetreat(ShmemVariableCache->latestCompletedXid); LWLockRelease(ProcArrayLock); /* * Start up the commit log and subtrans, if not already done for hot * standby. */ if (standbyState == STANDBY_DISABLED) { StartupCLOG(); StartupSUBTRANS(oldestActiveXID); } /* * Perform end of recovery actions for any SLRUs that need it. */ StartupMultiXact(); TrimCLOG(); /* Reload shared-memory state for prepared transactions */ RecoverPreparedTransactions(); /* * Shutdown the recovery environment. This must occur after * RecoverPreparedTransactions(), see notes for lock_twophase_recover() */ if (standbyState != STANDBY_DISABLED) ShutdownRecoveryTransactionEnvironment(); /* Shut down readFile facility, free space */ if (readFile >= 0) { close(readFile); readFile = -1; } if (readBuf) { free(readBuf); readBuf = NULL; } if (readRecordBuf) { free(readRecordBuf); readRecordBuf = NULL; readRecordBufSize = 0; } /* * If any of the critical GUCs have changed, log them before we allow * backends to write WAL. */ LocalSetXLogInsertAllowed(); XLogReportParameters(); /* * All done. Allow backends to write WAL. (Although the bool flag is * probably atomic in itself, we use the info_lck here to ensure that * there are no race conditions concerning visibility of other recent * updates to shared memory.) */ { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); xlogctl->SharedRecoveryInProgress = false; SpinLockRelease(&xlogctl->info_lck); } } /* * Checks if recovery has reached a consistent state. When consistency is * reached and we have a valid starting standby snapshot, tell postmaster * that it can start accepting read-only connections. */ static void CheckRecoveryConsistency(void) { /* * During crash recovery, we don't reach a consistent state until we've * replayed all the WAL. */ if (XLogRecPtrIsInvalid(minRecoveryPoint)) return; /* * Have we passed our safe starting point? */ if (!reachedConsistency && XLByteLE(minRecoveryPoint, EndRecPtr) && XLogRecPtrIsInvalid(ControlFile->backupStartPoint)) { /* * Check to see if the XLOG sequence contained any unresolved * references to uninitialized pages. */ XLogCheckInvalidPages(); reachedConsistency = true; ereport(LOG, (errmsg("consistent recovery state reached at %X/%X", EndRecPtr.xlogid, EndRecPtr.xrecoff))); } /* * Have we got a valid starting snapshot that will allow queries to be * run? If so, we can tell postmaster that the database is consistent now, * enabling connections. */ if (standbyState == STANDBY_SNAPSHOT_READY && !LocalHotStandbyActive && reachedConsistency && IsUnderPostmaster) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); xlogctl->SharedHotStandbyActive = true; SpinLockRelease(&xlogctl->info_lck); LocalHotStandbyActive = true; SendPostmasterSignal(PMSIGNAL_BEGIN_HOT_STANDBY); } } /* * Is the system still in recovery? * * Unlike testing InRecovery, this works in any process that's connected to * shared memory. * * As a side-effect, we initialize the local TimeLineID and RedoRecPtr * variables the first time we see that recovery is finished. */ bool RecoveryInProgress(void) { /* * We check shared state each time only until we leave recovery mode. We * can't re-enter recovery, so there's no need to keep checking after the * shared variable has once been seen false. */ if (!LocalRecoveryInProgress) return false; else { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; /* spinlock is essential on machines with weak memory ordering! */ SpinLockAcquire(&xlogctl->info_lck); LocalRecoveryInProgress = xlogctl->SharedRecoveryInProgress; SpinLockRelease(&xlogctl->info_lck); /* * Initialize TimeLineID and RedoRecPtr when we discover that recovery * is finished. InitPostgres() relies upon this behaviour to ensure * that InitXLOGAccess() is called at backend startup. (If you change * this, see also LocalSetXLogInsertAllowed.) */ if (!LocalRecoveryInProgress) InitXLOGAccess(); return LocalRecoveryInProgress; } } /* * Is HotStandby active yet? This is only important in special backends * since normal backends won't ever be able to connect until this returns * true. Postmaster knows this by way of signal, not via shared memory. * * Unlike testing standbyState, this works in any process that's connected to * shared memory. */ bool HotStandbyActive(void) { /* * We check shared state each time only until Hot Standby is active. We * can't de-activate Hot Standby, so there's no need to keep checking * after the shared variable has once been seen true. */ if (LocalHotStandbyActive) return true; else { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; /* spinlock is essential on machines with weak memory ordering! */ SpinLockAcquire(&xlogctl->info_lck); LocalHotStandbyActive = xlogctl->SharedHotStandbyActive; SpinLockRelease(&xlogctl->info_lck); return LocalHotStandbyActive; } } /* * Is this process allowed to insert new WAL records? * * Ordinarily this is essentially equivalent to !RecoveryInProgress(). * But we also have provisions for forcing the result "true" or "false" * within specific processes regardless of the global state. */ bool XLogInsertAllowed(void) { /* * If value is "unconditionally true" or "unconditionally false", just * return it. This provides the normal fast path once recovery is known * done. */ if (LocalXLogInsertAllowed >= 0) return (bool) LocalXLogInsertAllowed; /* * Else, must check to see if we're still in recovery. */ if (RecoveryInProgress()) return false; /* * On exit from recovery, reset to "unconditionally true", since there is * no need to keep checking. */ LocalXLogInsertAllowed = 1; return true; } /* * Make XLogInsertAllowed() return true in the current process only. * * Note: it is allowed to switch LocalXLogInsertAllowed back to -1 later, * and even call LocalSetXLogInsertAllowed() again after that. */ static void LocalSetXLogInsertAllowed(void) { Assert(LocalXLogInsertAllowed == -1); LocalXLogInsertAllowed = 1; /* Initialize as RecoveryInProgress() would do when switching state */ InitXLOGAccess(); } /* * Subroutine to try to fetch and validate a prior checkpoint record. * * whichChkpt identifies the checkpoint (merely for reporting purposes). * 1 for "primary", 2 for "secondary", 0 for "other" (backup_label) */ static XLogRecord * ReadCheckpointRecord(XLogRecPtr RecPtr, int whichChkpt) { XLogRecord *record; if (!XRecOffIsValid(RecPtr.xrecoff)) { switch (whichChkpt) { case 1: ereport(LOG, (errmsg("invalid primary checkpoint link in control file"))); break; case 2: ereport(LOG, (errmsg("invalid secondary checkpoint link in control file"))); break; default: ereport(LOG, (errmsg("invalid checkpoint link in backup_label file"))); break; } return NULL; } record = ReadRecord(&RecPtr, LOG, true); if (record == NULL) { switch (whichChkpt) { case 1: ereport(LOG, (errmsg("invalid primary checkpoint record"))); break; case 2: ereport(LOG, (errmsg("invalid secondary checkpoint record"))); break; default: ereport(LOG, (errmsg("invalid checkpoint record"))); break; } return NULL; } if (record->xl_rmid != RM_XLOG_ID) { switch (whichChkpt) { case 1: ereport(LOG, (errmsg("invalid resource manager ID in primary checkpoint record"))); break; case 2: ereport(LOG, (errmsg("invalid resource manager ID in secondary checkpoint record"))); break; default: ereport(LOG, (errmsg("invalid resource manager ID in checkpoint record"))); break; } return NULL; } if (record->xl_info != XLOG_CHECKPOINT_SHUTDOWN && record->xl_info != XLOG_CHECKPOINT_ONLINE) { switch (whichChkpt) { case 1: ereport(LOG, (errmsg("invalid xl_info in primary checkpoint record"))); break; case 2: ereport(LOG, (errmsg("invalid xl_info in secondary checkpoint record"))); break; default: ereport(LOG, (errmsg("invalid xl_info in checkpoint record"))); break; } return NULL; } if (record->xl_len != sizeof(CheckPoint) || record->xl_tot_len != SizeOfXLogRecord + sizeof(CheckPoint)) { switch (whichChkpt) { case 1: ereport(LOG, (errmsg("invalid length of primary checkpoint record"))); break; case 2: ereport(LOG, (errmsg("invalid length of secondary checkpoint record"))); break; default: ereport(LOG, (errmsg("invalid length of checkpoint record"))); break; } return NULL; } return record; } /* * This must be called during startup of a backend process, except that * it need not be called in a standalone backend (which does StartupXLOG * instead). We need to initialize the local copies of ThisTimeLineID and * RedoRecPtr. * * Note: before Postgres 8.0, we went to some effort to keep the postmaster * process's copies of ThisTimeLineID and RedoRecPtr valid too. This was * unnecessary however, since the postmaster itself never touches XLOG anyway. */ void InitXLOGAccess(void) { /* ThisTimeLineID doesn't change so we need no lock to copy it */ ThisTimeLineID = XLogCtl->ThisTimeLineID; Assert(ThisTimeLineID != 0 || IsBootstrapProcessingMode()); /* Use GetRedoRecPtr to copy the RedoRecPtr safely */ (void) GetRedoRecPtr(); } /* * Once spawned, a backend may update its local RedoRecPtr from * XLogCtl->Insert.RedoRecPtr; it must hold the insert lock or info_lck * to do so. This is done in XLogInsert() or GetRedoRecPtr(). */ XLogRecPtr GetRedoRecPtr(void) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); Assert(XLByteLE(RedoRecPtr, xlogctl->Insert.RedoRecPtr)); RedoRecPtr = xlogctl->Insert.RedoRecPtr; SpinLockRelease(&xlogctl->info_lck); return RedoRecPtr; } /* * GetInsertRecPtr -- Returns the current insert position. * * NOTE: The value *actually* returned is the position of the last full * xlog page. It lags behind the real insert position by at most 1 page. * For that, we don't need to acquire WALInsertLock which can be quite * heavily contended, and an approximation is enough for the current * usage of this function. */ XLogRecPtr GetInsertRecPtr(void) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; XLogRecPtr recptr; SpinLockAcquire(&xlogctl->info_lck); recptr = xlogctl->LogwrtRqst.Write; SpinLockRelease(&xlogctl->info_lck); return recptr; } /* * GetFlushRecPtr -- Returns the current flush position, ie, the last WAL * position known to be fsync'd to disk. */ XLogRecPtr GetFlushRecPtr(void) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; XLogRecPtr recptr; SpinLockAcquire(&xlogctl->info_lck); recptr = xlogctl->LogwrtResult.Flush; SpinLockRelease(&xlogctl->info_lck); return recptr; } /* * Get the time of the last xlog segment switch */ pg_time_t GetLastSegSwitchTime(void) { pg_time_t result; /* Need WALWriteLock, but shared lock is sufficient */ LWLockAcquire(WALWriteLock, LW_SHARED); result = XLogCtl->Write.lastSegSwitchTime; LWLockRelease(WALWriteLock); return result; } /* * GetNextXidAndEpoch - get the current nextXid value and associated epoch * * This is exported for use by code that would like to have 64-bit XIDs. * We don't really support such things, but all XIDs within the system * can be presumed "close to" the result, and thus the epoch associated * with them can be determined. */ void GetNextXidAndEpoch(TransactionId *xid, uint32 *epoch) { uint32 ckptXidEpoch; TransactionId ckptXid; TransactionId nextXid; /* Must read checkpoint info first, else have race condition */ { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); ckptXidEpoch = xlogctl->ckptXidEpoch; ckptXid = xlogctl->ckptXid; SpinLockRelease(&xlogctl->info_lck); } /* Now fetch current nextXid */ nextXid = ReadNewTransactionId(); /* * nextXid is certainly logically later than ckptXid. So if it's * numerically less, it must have wrapped into the next epoch. */ if (nextXid < ckptXid) ckptXidEpoch++; *xid = nextXid; *epoch = ckptXidEpoch; } /* * GetRecoveryTargetTLI - get the recovery target timeline ID */ TimeLineID GetRecoveryTargetTLI(void) { /* RecoveryTargetTLI doesn't change so we need no lock to copy it */ return XLogCtl->RecoveryTargetTLI; } /* * This must be called ONCE during postmaster or standalone-backend shutdown */ void ShutdownXLOG(int code, Datum arg) { ereport(LOG, (errmsg("shutting down"))); if (RecoveryInProgress()) CreateRestartPoint(CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_IMMEDIATE); else { /* * If archiving is enabled, rotate the last XLOG file so that all the * remaining records are archived (postmaster wakes up the archiver * process one more time at the end of shutdown). The checkpoint * record will go to the next XLOG file and won't be archived (yet). */ if (XLogArchivingActive() && XLogArchiveCommandSet()) RequestXLogSwitch(); CreateCheckPoint(CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_IMMEDIATE); } ShutdownCLOG(); ShutdownSUBTRANS(); ShutdownMultiXact(); ereport(LOG, (errmsg("database system is shut down"))); } /* * Log start of a checkpoint. */ static void LogCheckpointStart(int flags, bool restartpoint) { const char *msg; /* * XXX: This is hopelessly untranslatable. We could call gettext_noop for * the main message, but what about all the flags? */ if (restartpoint) msg = "restartpoint starting:%s%s%s%s%s%s%s"; else msg = "checkpoint starting:%s%s%s%s%s%s%s"; elog(LOG, msg, (flags & CHECKPOINT_IS_SHUTDOWN) ? " shutdown" : "", (flags & CHECKPOINT_END_OF_RECOVERY) ? " end-of-recovery" : "", (flags & CHECKPOINT_IMMEDIATE) ? " immediate" : "", (flags & CHECKPOINT_FORCE) ? " force" : "", (flags & CHECKPOINT_WAIT) ? " wait" : "", (flags & CHECKPOINT_CAUSE_XLOG) ? " xlog" : "", (flags & CHECKPOINT_CAUSE_TIME) ? " time" : ""); } /* * Log end of a checkpoint. */ static void LogCheckpointEnd(bool restartpoint) { long write_secs, sync_secs, total_secs, longest_secs, average_secs; int write_usecs, sync_usecs, total_usecs, longest_usecs, average_usecs; uint64 average_sync_time; CheckpointStats.ckpt_end_t = GetCurrentTimestamp(); TimestampDifference(CheckpointStats.ckpt_write_t, CheckpointStats.ckpt_sync_t, &write_secs, &write_usecs); TimestampDifference(CheckpointStats.ckpt_sync_t, CheckpointStats.ckpt_sync_end_t, &sync_secs, &sync_usecs); /* Accumulate checkpoint timing summary data, in milliseconds. */ BgWriterStats.m_checkpoint_write_time += write_secs * 1000 + write_usecs / 1000; BgWriterStats.m_checkpoint_sync_time += sync_secs * 1000 + sync_usecs / 1000; /* * All of the published timing statistics are accounted for. Only * continue if a log message is to be written. */ if (!log_checkpoints) return; TimestampDifference(CheckpointStats.ckpt_start_t, CheckpointStats.ckpt_end_t, &total_secs, &total_usecs); /* * Timing values returned from CheckpointStats are in microseconds. * Convert to the second plus microsecond form that TimestampDifference * returns for homogeneous printing. */ longest_secs = (long) (CheckpointStats.ckpt_longest_sync / 1000000); longest_usecs = CheckpointStats.ckpt_longest_sync - (uint64) longest_secs *1000000; average_sync_time = 0; if (CheckpointStats.ckpt_sync_rels > 0) average_sync_time = CheckpointStats.ckpt_agg_sync_time / CheckpointStats.ckpt_sync_rels; average_secs = (long) (average_sync_time / 1000000); average_usecs = average_sync_time - (uint64) average_secs *1000000; if (restartpoint) elog(LOG, "restartpoint complete: wrote %d buffers (%.1f%%); " "%d transaction log file(s) added, %d removed, %d recycled; " "write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s; " "sync files=%d, longest=%ld.%03d s, average=%ld.%03d s", CheckpointStats.ckpt_bufs_written, (double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers, CheckpointStats.ckpt_segs_added, CheckpointStats.ckpt_segs_removed, CheckpointStats.ckpt_segs_recycled, write_secs, write_usecs / 1000, sync_secs, sync_usecs / 1000, total_secs, total_usecs / 1000, CheckpointStats.ckpt_sync_rels, longest_secs, longest_usecs / 1000, average_secs, average_usecs / 1000); else elog(LOG, "checkpoint complete: wrote %d buffers (%.1f%%); " "%d transaction log file(s) added, %d removed, %d recycled; " "write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s; " "sync files=%d, longest=%ld.%03d s, average=%ld.%03d s", CheckpointStats.ckpt_bufs_written, (double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers, CheckpointStats.ckpt_segs_added, CheckpointStats.ckpt_segs_removed, CheckpointStats.ckpt_segs_recycled, write_secs, write_usecs / 1000, sync_secs, sync_usecs / 1000, total_secs, total_usecs / 1000, CheckpointStats.ckpt_sync_rels, longest_secs, longest_usecs / 1000, average_secs, average_usecs / 1000); } /* * Perform a checkpoint --- either during shutdown, or on-the-fly * * flags is a bitwise OR of the following: * CHECKPOINT_IS_SHUTDOWN: checkpoint is for database shutdown. * CHECKPOINT_END_OF_RECOVERY: checkpoint is for end of WAL recovery. * CHECKPOINT_IMMEDIATE: finish the checkpoint ASAP, * ignoring checkpoint_completion_target parameter. * CHECKPOINT_FORCE: force a checkpoint even if no XLOG activity has occurred * since the last one (implied by CHECKPOINT_IS_SHUTDOWN or * CHECKPOINT_END_OF_RECOVERY). * * Note: flags contains other bits, of interest here only for logging purposes. * In particular note that this routine is synchronous and does not pay * attention to CHECKPOINT_WAIT. */ void CreateCheckPoint(int flags) { bool shutdown; CheckPoint checkPoint; XLogRecPtr recptr; XLogCtlInsert *Insert = &XLogCtl->Insert; XLogRecData rdata; uint32 freespace; uint32 _logId; uint32 _logSeg; TransactionId *inCommitXids; int nInCommit; /* * An end-of-recovery checkpoint is really a shutdown checkpoint, just * issued at a different time. */ if (flags & (CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_END_OF_RECOVERY)) shutdown = true; else shutdown = false; /* sanity check */ if (RecoveryInProgress() && (flags & CHECKPOINT_END_OF_RECOVERY) == 0) elog(ERROR, "can't create a checkpoint during recovery"); /* * Acquire CheckpointLock to ensure only one checkpoint happens at a time. * (This is just pro forma, since in the present system structure there is * only one process that is allowed to issue checkpoints at any given * time.) */ LWLockAcquire(CheckpointLock, LW_EXCLUSIVE); /* * Prepare to accumulate statistics. * * Note: because it is possible for log_checkpoints to change while a * checkpoint proceeds, we always accumulate stats, even if * log_checkpoints is currently off. */ MemSet(&CheckpointStats, 0, sizeof(CheckpointStats)); CheckpointStats.ckpt_start_t = GetCurrentTimestamp(); /* * Use a critical section to force system panic if we have trouble. */ START_CRIT_SECTION(); if (shutdown) { LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); ControlFile->state = DB_SHUTDOWNING; ControlFile->time = (pg_time_t) time(NULL); UpdateControlFile(); LWLockRelease(ControlFileLock); } /* * Let smgr prepare for checkpoint; this has to happen before we determine * the REDO pointer. Note that smgr must not do anything that'd have to * be undone if we decide no checkpoint is needed. */ smgrpreckpt(); /* Begin filling in the checkpoint WAL record */ MemSet(&checkPoint, 0, sizeof(checkPoint)); checkPoint.time = (pg_time_t) time(NULL); /* * For Hot Standby, derive the oldestActiveXid before we fix the redo * pointer. This allows us to begin accumulating changes to assemble our * starting snapshot of locks and transactions. */ if (!shutdown && XLogStandbyInfoActive()) checkPoint.oldestActiveXid = GetOldestActiveTransactionId(); else checkPoint.oldestActiveXid = InvalidTransactionId; /* * We must hold WALInsertLock while examining insert state to determine * the checkpoint REDO pointer. */ LWLockAcquire(WALInsertLock, LW_EXCLUSIVE); /* * If this isn't a shutdown or forced checkpoint, and we have not inserted * any XLOG records since the start of the last checkpoint, skip the * checkpoint. The idea here is to avoid inserting duplicate checkpoints * when the system is idle. That wastes log space, and more importantly it * exposes us to possible loss of both current and previous checkpoint * records if the machine crashes just as we're writing the update. * (Perhaps it'd make even more sense to checkpoint only when the previous * checkpoint record is in a different xlog page?) * * We have to make two tests to determine that nothing has happened since * the start of the last checkpoint: current insertion point must match * the end of the last checkpoint record, and its redo pointer must point * to itself. */ if ((flags & (CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_END_OF_RECOVERY | CHECKPOINT_FORCE)) == 0) { XLogRecPtr curInsert; INSERT_RECPTR(curInsert, Insert, Insert->curridx); if (curInsert.xlogid == ControlFile->checkPoint.xlogid && curInsert.xrecoff == ControlFile->checkPoint.xrecoff + MAXALIGN(SizeOfXLogRecord + sizeof(CheckPoint)) && ControlFile->checkPoint.xlogid == ControlFile->checkPointCopy.redo.xlogid && ControlFile->checkPoint.xrecoff == ControlFile->checkPointCopy.redo.xrecoff) { LWLockRelease(WALInsertLock); LWLockRelease(CheckpointLock); END_CRIT_SECTION(); return; } } /* * An end-of-recovery checkpoint is created before anyone is allowed to * write WAL. To allow us to write the checkpoint record, temporarily * enable XLogInsertAllowed. (This also ensures ThisTimeLineID is * initialized, which we need here and in AdvanceXLInsertBuffer.) */ if (flags & CHECKPOINT_END_OF_RECOVERY) LocalSetXLogInsertAllowed(); checkPoint.ThisTimeLineID = ThisTimeLineID; checkPoint.fullPageWrites = Insert->fullPageWrites; /* * Compute new REDO record ptr = location of next XLOG record. * * NB: this is NOT necessarily where the checkpoint record itself will be, * since other backends may insert more XLOG records while we're off doing * the buffer flush work. Those XLOG records are logically after the * checkpoint, even though physically before it. Got that? */ freespace = INSERT_FREESPACE(Insert); if (freespace < SizeOfXLogRecord) { (void) AdvanceXLInsertBuffer(false); /* OK to ignore update return flag, since we will do flush anyway */ freespace = INSERT_FREESPACE(Insert); } INSERT_RECPTR(checkPoint.redo, Insert, Insert->curridx); /* * Here we update the shared RedoRecPtr for future XLogInsert calls; this * must be done while holding the insert lock AND the info_lck. * * Note: if we fail to complete the checkpoint, RedoRecPtr will be left * pointing past where it really needs to point. This is okay; the only * consequence is that XLogInsert might back up whole buffers that it * didn't really need to. We can't postpone advancing RedoRecPtr because * XLogInserts that happen while we are dumping buffers must assume that * their buffer changes are not included in the checkpoint. */ { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); RedoRecPtr = xlogctl->Insert.RedoRecPtr = checkPoint.redo; SpinLockRelease(&xlogctl->info_lck); } /* * Now we can release WAL insert lock, allowing other xacts to proceed * while we are flushing disk buffers. */ LWLockRelease(WALInsertLock); /* * If enabled, log checkpoint start. We postpone this until now so as not * to log anything if we decided to skip the checkpoint. */ if (log_checkpoints) LogCheckpointStart(flags, false); TRACE_POSTGRESQL_CHECKPOINT_START(flags); /* * Before flushing data, we must wait for any transactions that are * currently in their commit critical sections. If an xact inserted its * commit record into XLOG just before the REDO point, then a crash * restart from the REDO point would not replay that record, which means * that our flushing had better include the xact's update of pg_clog. So * we wait till he's out of his commit critical section before proceeding. * See notes in RecordTransactionCommit(). * * Because we've already released WALInsertLock, this test is a bit fuzzy: * it is possible that we will wait for xacts we didn't really need to * wait for. But the delay should be short and it seems better to make * checkpoint take a bit longer than to hold locks longer than necessary. * (In fact, the whole reason we have this issue is that xact.c does * commit record XLOG insertion and clog update as two separate steps * protected by different locks, but again that seems best on grounds of * minimizing lock contention.) * * A transaction that has not yet set inCommit when we look cannot be at * risk, since he's not inserted his commit record yet; and one that's * already cleared it is not at risk either, since he's done fixing clog * and we will correctly flush the update below. So we cannot miss any * xacts we need to wait for. */ nInCommit = GetTransactionsInCommit(&inCommitXids); if (nInCommit > 0) { do { pg_usleep(10000L); /* wait for 10 msec */ } while (HaveTransactionsInCommit(inCommitXids, nInCommit)); } pfree(inCommitXids); /* * Get the other info we need for the checkpoint record. */ LWLockAcquire(XidGenLock, LW_SHARED); checkPoint.nextXid = ShmemVariableCache->nextXid; checkPoint.oldestXid = ShmemVariableCache->oldestXid; checkPoint.oldestXidDB = ShmemVariableCache->oldestXidDB; LWLockRelease(XidGenLock); /* Increase XID epoch if we've wrapped around since last checkpoint */ checkPoint.nextXidEpoch = ControlFile->checkPointCopy.nextXidEpoch; if (checkPoint.nextXid < ControlFile->checkPointCopy.nextXid) checkPoint.nextXidEpoch++; LWLockAcquire(OidGenLock, LW_SHARED); checkPoint.nextOid = ShmemVariableCache->nextOid; if (!shutdown) checkPoint.nextOid += ShmemVariableCache->oidCount; LWLockRelease(OidGenLock); MultiXactGetCheckptMulti(shutdown, &checkPoint.nextMulti, &checkPoint.nextMultiOffset); /* * Having constructed the checkpoint record, ensure all shmem disk buffers * and commit-log buffers are flushed to disk. * * This I/O could fail for various reasons. If so, we will fail to * complete the checkpoint, but there is no reason to force a system * panic. Accordingly, exit critical section while doing it. */ END_CRIT_SECTION(); CheckPointGuts(checkPoint.redo, flags); /* * Take a snapshot of running transactions and write this to WAL. This * allows us to reconstruct the state of running transactions during * archive recovery, if required. Skip, if this info disabled. * * If we are shutting down, or Startup process is completing crash * recovery we don't need to write running xact data. * * Update checkPoint.nextXid since we have a later value */ if (!shutdown && XLogStandbyInfoActive()) LogStandbySnapshot(&checkPoint.nextXid); START_CRIT_SECTION(); /* * Now insert the checkpoint record into XLOG. */ rdata.data = (char *) (&checkPoint); rdata.len = sizeof(checkPoint); rdata.buffer = InvalidBuffer; rdata.next = NULL; recptr = XLogInsert(RM_XLOG_ID, shutdown ? XLOG_CHECKPOINT_SHUTDOWN : XLOG_CHECKPOINT_ONLINE, &rdata); XLogFlush(recptr); /* * We mustn't write any new WAL after a shutdown checkpoint, or it will be * overwritten at next startup. No-one should even try, this just allows * sanity-checking. In the case of an end-of-recovery checkpoint, we want * to just temporarily disable writing until the system has exited * recovery. */ if (shutdown) { if (flags & CHECKPOINT_END_OF_RECOVERY) LocalXLogInsertAllowed = -1; /* return to "check" state */ else LocalXLogInsertAllowed = 0; /* never again write WAL */ } /* * We now have ProcLastRecPtr = start of actual checkpoint record, recptr * = end of actual checkpoint record. */ if (shutdown && !XLByteEQ(checkPoint.redo, ProcLastRecPtr)) ereport(PANIC, (errmsg("concurrent transaction log activity while database system is shutting down"))); /* * Select point at which we can truncate the log, which we base on the * prior checkpoint's earliest info. */ XLByteToSeg(ControlFile->checkPointCopy.redo, _logId, _logSeg); /* * Update the control file. */ LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); if (shutdown) ControlFile->state = DB_SHUTDOWNED; ControlFile->prevCheckPoint = ControlFile->checkPoint; ControlFile->checkPoint = ProcLastRecPtr; ControlFile->checkPointCopy = checkPoint; ControlFile->time = (pg_time_t) time(NULL); /* crash recovery should always recover to the end of WAL */ MemSet(&ControlFile->minRecoveryPoint, 0, sizeof(XLogRecPtr)); UpdateControlFile(); LWLockRelease(ControlFileLock); /* Update shared-memory copy of checkpoint XID/epoch */ { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); xlogctl->ckptXidEpoch = checkPoint.nextXidEpoch; xlogctl->ckptXid = checkPoint.nextXid; SpinLockRelease(&xlogctl->info_lck); } /* * We are now done with critical updates; no need for system panic if we * have trouble while fooling with old log segments. */ END_CRIT_SECTION(); /* * Let smgr do post-checkpoint cleanup (eg, deleting old files). */ smgrpostckpt(); /* * Delete old log files (those no longer needed even for previous * checkpoint or the standbys in XLOG streaming). */ if (_logId || _logSeg) { KeepLogSeg(recptr, &_logId, &_logSeg); PrevLogSeg(_logId, _logSeg); RemoveOldXlogFiles(_logId, _logSeg, recptr); } /* * Make more log segments if needed. (Do this after recycling old log * segments, since that may supply some of the needed files.) */ if (!shutdown) PreallocXlogFiles(recptr); /* * Truncate pg_subtrans if possible. We can throw away all data before * the oldest XMIN of any running transaction. No future transaction will * attempt to reference any pg_subtrans entry older than that (see Asserts * in subtrans.c). During recovery, though, we mustn't do this because * StartupSUBTRANS hasn't been called yet. */ if (!RecoveryInProgress()) TruncateSUBTRANS(GetOldestXmin(true, false)); /* Real work is done, but log and update stats before releasing lock. */ LogCheckpointEnd(false); TRACE_POSTGRESQL_CHECKPOINT_DONE(CheckpointStats.ckpt_bufs_written, NBuffers, CheckpointStats.ckpt_segs_added, CheckpointStats.ckpt_segs_removed, CheckpointStats.ckpt_segs_recycled); LWLockRelease(CheckpointLock); } /* * Flush all data in shared memory to disk, and fsync * * This is the common code shared between regular checkpoints and * recovery restartpoints. */ static void CheckPointGuts(XLogRecPtr checkPointRedo, int flags) { CheckPointCLOG(); CheckPointSUBTRANS(); CheckPointMultiXact(); CheckPointPredicate(); CheckPointRelationMap(); CheckPointBuffers(flags); /* performs all required fsyncs */ /* We deliberately delay 2PC checkpointing as long as possible */ CheckPointTwoPhase(checkPointRedo); } /* * Save a checkpoint for recovery restart if appropriate * * This function is called each time a checkpoint record is read from XLOG. * It must determine whether the checkpoint represents a safe restartpoint or * not. If so, the checkpoint record is stashed in shared memory so that * CreateRestartPoint can consult it. (Note that the latter function is * executed by the checkpointer, while this one will be executed by the * startup process.) */ static void RecoveryRestartPoint(const CheckPoint *checkPoint) { int rmid; /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; /* * Is it safe to restartpoint? We must ask each of the resource managers * whether they have any partial state information that might prevent a * correct restart from this point. If so, we skip this opportunity, but * return at the next checkpoint record for another try. */ for (rmid = 0; rmid <= RM_MAX_ID; rmid++) { if (RmgrTable[rmid].rm_safe_restartpoint != NULL) if (!(RmgrTable[rmid].rm_safe_restartpoint())) { elog(trace_recovery(DEBUG2), "RM %d not safe to record restart point at %X/%X", rmid, checkPoint->redo.xlogid, checkPoint->redo.xrecoff); return; } } /* * Also refrain from creating a restartpoint if we have seen any * references to non-existent pages. Restarting recovery from the * restartpoint would not see the references, so we would lose the * cross-check that the pages belonged to a relation that was dropped * later. */ if (XLogHaveInvalidPages()) { elog(trace_recovery(DEBUG2), "could not record restart point at %X/%X because there " "are unresolved references to invalid pages", checkPoint->redo.xlogid, checkPoint->redo.xrecoff); return; } /* * Copy the checkpoint record to shared memory, so that checkpointer can * work out the next time it wants to perform a restartpoint. */ SpinLockAcquire(&xlogctl->info_lck); XLogCtl->lastCheckPointRecPtr = ReadRecPtr; memcpy(&XLogCtl->lastCheckPoint, checkPoint, sizeof(CheckPoint)); SpinLockRelease(&xlogctl->info_lck); } /* * Establish a restartpoint if possible. * * This is similar to CreateCheckPoint, but is used during WAL recovery * to establish a point from which recovery can roll forward without * replaying the entire recovery log. * * Returns true if a new restartpoint was established. We can only establish * a restartpoint if we have replayed a safe checkpoint record since last * restartpoint. */ bool CreateRestartPoint(int flags) { XLogRecPtr lastCheckPointRecPtr; CheckPoint lastCheckPoint; uint32 _logId; uint32 _logSeg; TimestampTz xtime; /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; /* * Acquire CheckpointLock to ensure only one restartpoint or checkpoint * happens at a time. */ LWLockAcquire(CheckpointLock, LW_EXCLUSIVE); /* Get a local copy of the last safe checkpoint record. */ SpinLockAcquire(&xlogctl->info_lck); lastCheckPointRecPtr = xlogctl->lastCheckPointRecPtr; memcpy(&lastCheckPoint, &XLogCtl->lastCheckPoint, sizeof(CheckPoint)); SpinLockRelease(&xlogctl->info_lck); /* * Check that we're still in recovery mode. It's ok if we exit recovery * mode after this check, the restart point is valid anyway. */ if (!RecoveryInProgress()) { ereport(DEBUG2, (errmsg("skipping restartpoint, recovery has already ended"))); LWLockRelease(CheckpointLock); return false; } /* * If the last checkpoint record we've replayed is already our last * restartpoint, we can't perform a new restart point. We still update * minRecoveryPoint in that case, so that if this is a shutdown restart * point, we won't start up earlier than before. That's not strictly * necessary, but when hot standby is enabled, it would be rather weird if * the database opened up for read-only connections at a point-in-time * before the last shutdown. Such time travel is still possible in case of * immediate shutdown, though. * * We don't explicitly advance minRecoveryPoint when we do create a * restartpoint. It's assumed that flushing the buffers will do that as a * side-effect. */ if (XLogRecPtrIsInvalid(lastCheckPointRecPtr) || XLByteLE(lastCheckPoint.redo, ControlFile->checkPointCopy.redo)) { ereport(DEBUG2, (errmsg("skipping restartpoint, already performed at %X/%X", lastCheckPoint.redo.xlogid, lastCheckPoint.redo.xrecoff))); UpdateMinRecoveryPoint(InvalidXLogRecPtr, true); if (flags & CHECKPOINT_IS_SHUTDOWN) { LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); ControlFile->state = DB_SHUTDOWNED_IN_RECOVERY; ControlFile->time = (pg_time_t) time(NULL); UpdateControlFile(); LWLockRelease(ControlFileLock); } LWLockRelease(CheckpointLock); return false; } /* * Update the shared RedoRecPtr so that the startup process can calculate * the number of segments replayed since last restartpoint, and request a * restartpoint if it exceeds checkpoint_segments. * * You need to hold WALInsertLock and info_lck to update it, although * during recovery acquiring WALInsertLock is just pro forma, because * there is no other processes updating Insert.RedoRecPtr. */ LWLockAcquire(WALInsertLock, LW_EXCLUSIVE); SpinLockAcquire(&xlogctl->info_lck); xlogctl->Insert.RedoRecPtr = lastCheckPoint.redo; SpinLockRelease(&xlogctl->info_lck); LWLockRelease(WALInsertLock); /* * Prepare to accumulate statistics. * * Note: because it is possible for log_checkpoints to change while a * checkpoint proceeds, we always accumulate stats, even if * log_checkpoints is currently off. */ MemSet(&CheckpointStats, 0, sizeof(CheckpointStats)); CheckpointStats.ckpt_start_t = GetCurrentTimestamp(); if (log_checkpoints) LogCheckpointStart(flags, true); CheckPointGuts(lastCheckPoint.redo, flags); /* * Select point at which we can truncate the xlog, which we base on the * prior checkpoint's earliest info. */ XLByteToSeg(ControlFile->checkPointCopy.redo, _logId, _logSeg); /* * Update pg_control, using current time. Check that it still shows * IN_ARCHIVE_RECOVERY state and an older checkpoint, else do nothing; * this is a quick hack to make sure nothing really bad happens if somehow * we get here after the end-of-recovery checkpoint. */ LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); if (ControlFile->state == DB_IN_ARCHIVE_RECOVERY && XLByteLT(ControlFile->checkPointCopy.redo, lastCheckPoint.redo)) { ControlFile->prevCheckPoint = ControlFile->checkPoint; ControlFile->checkPoint = lastCheckPointRecPtr; ControlFile->checkPointCopy = lastCheckPoint; ControlFile->time = (pg_time_t) time(NULL); if (flags & CHECKPOINT_IS_SHUTDOWN) ControlFile->state = DB_SHUTDOWNED_IN_RECOVERY; UpdateControlFile(); } LWLockRelease(ControlFileLock); /* * Delete old log files (those no longer needed even for previous * checkpoint/restartpoint) to prevent the disk holding the xlog from * growing full. */ if (_logId || _logSeg) { XLogRecPtr endptr; /* Get the current (or recent) end of xlog */ endptr = GetStandbyFlushRecPtr(); KeepLogSeg(endptr, &_logId, &_logSeg); PrevLogSeg(_logId, _logSeg); RemoveOldXlogFiles(_logId, _logSeg, endptr); /* * Make more log segments if needed. (Do this after recycling old log * segments, since that may supply some of the needed files.) */ PreallocXlogFiles(endptr); } /* * Truncate pg_subtrans if possible. We can throw away all data before * the oldest XMIN of any running transaction. No future transaction will * attempt to reference any pg_subtrans entry older than that (see Asserts * in subtrans.c). When hot standby is disabled, though, we mustn't do * this because StartupSUBTRANS hasn't been called yet. */ if (EnableHotStandby) TruncateSUBTRANS(GetOldestXmin(true, false)); /* Real work is done, but log and update before releasing lock. */ LogCheckpointEnd(true); xtime = GetLatestXTime(); ereport((log_checkpoints ? LOG : DEBUG2), (errmsg("recovery restart point at %X/%X", lastCheckPoint.redo.xlogid, lastCheckPoint.redo.xrecoff), xtime ? errdetail("last completed transaction was at log time %s", timestamptz_to_str(xtime)) : 0)); LWLockRelease(CheckpointLock); /* * Finally, execute archive_cleanup_command, if any. */ if (XLogCtl->archiveCleanupCommand[0]) ExecuteRecoveryCommand(XLogCtl->archiveCleanupCommand, "archive_cleanup_command", false); return true; } /* * Calculate the last segment that we need to retain because of * wal_keep_segments, by subtracting wal_keep_segments from * the given xlog location, recptr. */ static void KeepLogSeg(XLogRecPtr recptr, uint32 *logId, uint32 *logSeg) { uint32 log; uint32 seg; int d_log; int d_seg; if (wal_keep_segments == 0) return; XLByteToSeg(recptr, log, seg); d_seg = wal_keep_segments % XLogSegsPerFile; d_log = wal_keep_segments / XLogSegsPerFile; if (seg < d_seg) { d_log += 1; seg = seg - d_seg + XLogSegsPerFile; } else seg = seg - d_seg; /* avoid underflow, don't go below (0,1) */ if (log < d_log || (log == d_log && seg == 0)) { log = 0; seg = 1; } else log = log - d_log; /* don't delete WAL segments newer than the calculated segment */ if (log < *logId || (log == *logId && seg < *logSeg)) { *logId = log; *logSeg = seg; } } /* * Write a NEXTOID log record */ void XLogPutNextOid(Oid nextOid) { XLogRecData rdata; rdata.data = (char *) (&nextOid); rdata.len = sizeof(Oid); rdata.buffer = InvalidBuffer; rdata.next = NULL; (void) XLogInsert(RM_XLOG_ID, XLOG_NEXTOID, &rdata); /* * We need not flush the NEXTOID record immediately, because any of the * just-allocated OIDs could only reach disk as part of a tuple insert or * update that would have its own XLOG record that must follow the NEXTOID * record. Therefore, the standard buffer LSN interlock applied to those * records will ensure no such OID reaches disk before the NEXTOID record * does. * * Note, however, that the above statement only covers state "within" the * database. When we use a generated OID as a file or directory name, we * are in a sense violating the basic WAL rule, because that filesystem * change may reach disk before the NEXTOID WAL record does. The impact * of this is that if a database crash occurs immediately afterward, we * might after restart re-generate the same OID and find that it conflicts * with the leftover file or directory. But since for safety's sake we * always loop until finding a nonconflicting filename, this poses no real * problem in practice. See pgsql-hackers discussion 27-Sep-2006. */ } /* * Write an XLOG SWITCH record. * * Here we just blindly issue an XLogInsert request for the record. * All the magic happens inside XLogInsert. * * The return value is either the end+1 address of the switch record, * or the end+1 address of the prior segment if we did not need to * write a switch record because we are already at segment start. */ XLogRecPtr RequestXLogSwitch(void) { XLogRecPtr RecPtr; XLogRecData rdata; /* XLOG SWITCH, alone among xlog record types, has no data */ rdata.buffer = InvalidBuffer; rdata.data = NULL; rdata.len = 0; rdata.next = NULL; RecPtr = XLogInsert(RM_XLOG_ID, XLOG_SWITCH, &rdata); return RecPtr; } /* * Write a RESTORE POINT record */ XLogRecPtr XLogRestorePoint(const char *rpName) { XLogRecPtr RecPtr; XLogRecData rdata; xl_restore_point xlrec; xlrec.rp_time = GetCurrentTimestamp(); strncpy(xlrec.rp_name, rpName, MAXFNAMELEN); rdata.buffer = InvalidBuffer; rdata.data = (char *) &xlrec; rdata.len = sizeof(xl_restore_point); rdata.next = NULL; RecPtr = XLogInsert(RM_XLOG_ID, XLOG_RESTORE_POINT, &rdata); ereport(LOG, (errmsg("restore point \"%s\" created at %X/%X", rpName, RecPtr.xlogid, RecPtr.xrecoff))); return RecPtr; } /* * Check if any of the GUC parameters that are critical for hot standby * have changed, and update the value in pg_control file if necessary. */ static void XLogReportParameters(void) { if (wal_level != ControlFile->wal_level || MaxConnections != ControlFile->MaxConnections || max_prepared_xacts != ControlFile->max_prepared_xacts || max_locks_per_xact != ControlFile->max_locks_per_xact) { /* * The change in number of backend slots doesn't need to be WAL-logged * if archiving is not enabled, as you can't start archive recovery * with wal_level=minimal anyway. We don't really care about the * values in pg_control either if wal_level=minimal, but seems better * to keep them up-to-date to avoid confusion. */ if (wal_level != ControlFile->wal_level || XLogIsNeeded()) { XLogRecData rdata; xl_parameter_change xlrec; xlrec.MaxConnections = MaxConnections; xlrec.max_prepared_xacts = max_prepared_xacts; xlrec.max_locks_per_xact = max_locks_per_xact; xlrec.wal_level = wal_level; rdata.buffer = InvalidBuffer; rdata.data = (char *) &xlrec; rdata.len = sizeof(xlrec); rdata.next = NULL; XLogInsert(RM_XLOG_ID, XLOG_PARAMETER_CHANGE, &rdata); } ControlFile->MaxConnections = MaxConnections; ControlFile->max_prepared_xacts = max_prepared_xacts; ControlFile->max_locks_per_xact = max_locks_per_xact; ControlFile->wal_level = wal_level; UpdateControlFile(); } } /* * Update full_page_writes in shared memory, and write an * XLOG_FPW_CHANGE record if necessary. * * Note: this function assumes there is no other process running * concurrently that could update it. */ void UpdateFullPageWrites(void) { XLogCtlInsert *Insert = &XLogCtl->Insert; /* * Do nothing if full_page_writes has not been changed. * * It's safe to check the shared full_page_writes without the lock, * because we assume that there is no concurrently running process which * can update it. */ if (fullPageWrites == Insert->fullPageWrites) return; START_CRIT_SECTION(); /* * It's always safe to take full page images, even when not strictly * required, but not the other round. So if we're setting full_page_writes * to true, first set it true and then write the WAL record. If we're * setting it to false, first write the WAL record and then set the global * flag. */ if (fullPageWrites) { LWLockAcquire(WALInsertLock, LW_EXCLUSIVE); Insert->fullPageWrites = true; LWLockRelease(WALInsertLock); } /* * Write an XLOG_FPW_CHANGE record. This allows us to keep track of * full_page_writes during archive recovery, if required. */ if (XLogStandbyInfoActive() && !RecoveryInProgress()) { XLogRecData rdata; rdata.data = (char *) (&fullPageWrites); rdata.len = sizeof(bool); rdata.buffer = InvalidBuffer; rdata.next = NULL; XLogInsert(RM_XLOG_ID, XLOG_FPW_CHANGE, &rdata); } if (!fullPageWrites) { LWLockAcquire(WALInsertLock, LW_EXCLUSIVE); Insert->fullPageWrites = false; LWLockRelease(WALInsertLock); } END_CRIT_SECTION(); } /* * XLOG resource manager's routines * * Definitions of info values are in include/catalog/pg_control.h, though * not all record types are related to control file updates. */ void xlog_redo(XLogRecPtr lsn, XLogRecord *record) { uint8 info = record->xl_info & ~XLR_INFO_MASK; /* Backup blocks are not used in xlog records */ Assert(!(record->xl_info & XLR_BKP_BLOCK_MASK)); if (info == XLOG_NEXTOID) { Oid nextOid; /* * We used to try to take the maximum of ShmemVariableCache->nextOid * and the recorded nextOid, but that fails if the OID counter wraps * around. Since no OID allocation should be happening during replay * anyway, better to just believe the record exactly. We still take * OidGenLock while setting the variable, just in case. */ memcpy(&nextOid, XLogRecGetData(record), sizeof(Oid)); LWLockAcquire(OidGenLock, LW_EXCLUSIVE); ShmemVariableCache->nextOid = nextOid; ShmemVariableCache->oidCount = 0; LWLockRelease(OidGenLock); } else if (info == XLOG_CHECKPOINT_SHUTDOWN) { CheckPoint checkPoint; memcpy(&checkPoint, XLogRecGetData(record), sizeof(CheckPoint)); /* In a SHUTDOWN checkpoint, believe the counters exactly */ LWLockAcquire(XidGenLock, LW_EXCLUSIVE); ShmemVariableCache->nextXid = checkPoint.nextXid; LWLockRelease(XidGenLock); LWLockAcquire(OidGenLock, LW_EXCLUSIVE); ShmemVariableCache->nextOid = checkPoint.nextOid; ShmemVariableCache->oidCount = 0; LWLockRelease(OidGenLock); MultiXactSetNextMXact(checkPoint.nextMulti, checkPoint.nextMultiOffset); SetTransactionIdLimit(checkPoint.oldestXid, checkPoint.oldestXidDB); /* * If we see a shutdown checkpoint while waiting for an end-of-backup * record, the backup was canceled and the end-of-backup record will * never arrive. */ if (InArchiveRecovery && !XLogRecPtrIsInvalid(ControlFile->backupStartPoint) && XLogRecPtrIsInvalid(ControlFile->backupEndPoint)) ereport(PANIC, (errmsg("online backup was canceled, recovery cannot continue"))); /* * If we see a shutdown checkpoint, we know that nothing was running * on the master at this point. So fake-up an empty running-xacts * record and use that here and now. Recover additional standby state * for prepared transactions. */ if (standbyState >= STANDBY_INITIALIZED) { TransactionId *xids; int nxids; TransactionId oldestActiveXID; TransactionId latestCompletedXid; RunningTransactionsData running; oldestActiveXID = PrescanPreparedTransactions(&xids, &nxids); /* * Construct a RunningTransactions snapshot representing a shut * down server, with only prepared transactions still alive. We're * never overflowed at this point because all subxids are listed * with their parent prepared transactions. */ running.xcnt = nxids; running.subxid_overflow = false; running.nextXid = checkPoint.nextXid; running.oldestRunningXid = oldestActiveXID; latestCompletedXid = checkPoint.nextXid; TransactionIdRetreat(latestCompletedXid); Assert(TransactionIdIsNormal(latestCompletedXid)); running.latestCompletedXid = latestCompletedXid; running.xids = xids; ProcArrayApplyRecoveryInfo(&running); StandbyRecoverPreparedTransactions(true); } /* ControlFile->checkPointCopy always tracks the latest ckpt XID */ ControlFile->checkPointCopy.nextXidEpoch = checkPoint.nextXidEpoch; ControlFile->checkPointCopy.nextXid = checkPoint.nextXid; /* Update shared-memory copy of checkpoint XID/epoch */ { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); xlogctl->ckptXidEpoch = checkPoint.nextXidEpoch; xlogctl->ckptXid = checkPoint.nextXid; SpinLockRelease(&xlogctl->info_lck); } /* * TLI may change in a shutdown checkpoint, but it shouldn't decrease */ if (checkPoint.ThisTimeLineID != ThisTimeLineID) { if (checkPoint.ThisTimeLineID < ThisTimeLineID || !list_member_int(expectedTLIs, (int) checkPoint.ThisTimeLineID)) ereport(PANIC, (errmsg("unexpected timeline ID %u (after %u) in checkpoint record", checkPoint.ThisTimeLineID, ThisTimeLineID))); /* Following WAL records should be run with new TLI */ ThisTimeLineID = checkPoint.ThisTimeLineID; } RecoveryRestartPoint(&checkPoint); } else if (info == XLOG_CHECKPOINT_ONLINE) { CheckPoint checkPoint; memcpy(&checkPoint, XLogRecGetData(record), sizeof(CheckPoint)); /* In an ONLINE checkpoint, treat the XID counter as a minimum */ LWLockAcquire(XidGenLock, LW_EXCLUSIVE); if (TransactionIdPrecedes(ShmemVariableCache->nextXid, checkPoint.nextXid)) ShmemVariableCache->nextXid = checkPoint.nextXid; LWLockRelease(XidGenLock); /* ... but still treat OID counter as exact */ LWLockAcquire(OidGenLock, LW_EXCLUSIVE); ShmemVariableCache->nextOid = checkPoint.nextOid; ShmemVariableCache->oidCount = 0; LWLockRelease(OidGenLock); MultiXactAdvanceNextMXact(checkPoint.nextMulti, checkPoint.nextMultiOffset); if (TransactionIdPrecedes(ShmemVariableCache->oldestXid, checkPoint.oldestXid)) SetTransactionIdLimit(checkPoint.oldestXid, checkPoint.oldestXidDB); /* ControlFile->checkPointCopy always tracks the latest ckpt XID */ ControlFile->checkPointCopy.nextXidEpoch = checkPoint.nextXidEpoch; ControlFile->checkPointCopy.nextXid = checkPoint.nextXid; /* Update shared-memory copy of checkpoint XID/epoch */ { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); xlogctl->ckptXidEpoch = checkPoint.nextXidEpoch; xlogctl->ckptXid = checkPoint.nextXid; SpinLockRelease(&xlogctl->info_lck); } /* TLI should not change in an on-line checkpoint */ if (checkPoint.ThisTimeLineID != ThisTimeLineID) ereport(PANIC, (errmsg("unexpected timeline ID %u (should be %u) in checkpoint record", checkPoint.ThisTimeLineID, ThisTimeLineID))); RecoveryRestartPoint(&checkPoint); } else if (info == XLOG_NOOP) { /* nothing to do here */ } else if (info == XLOG_SWITCH) { /* nothing to do here */ } else if (info == XLOG_RESTORE_POINT) { /* nothing to do here */ } else if (info == XLOG_BACKUP_END) { XLogRecPtr startpoint; memcpy(&startpoint, XLogRecGetData(record), sizeof(startpoint)); if (XLByteEQ(ControlFile->backupStartPoint, startpoint)) { /* * We have reached the end of base backup, the point where * pg_stop_backup() was done. The data on disk is now consistent. * Reset backupStartPoint, and update minRecoveryPoint to make * sure we don't allow starting up at an earlier point even if * recovery is stopped and restarted soon after this. */ elog(DEBUG1, "end of backup reached"); LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); if (XLByteLT(ControlFile->minRecoveryPoint, lsn)) ControlFile->minRecoveryPoint = lsn; MemSet(&ControlFile->backupStartPoint, 0, sizeof(XLogRecPtr)); ControlFile->backupEndRequired = false; UpdateControlFile(); LWLockRelease(ControlFileLock); } } else if (info == XLOG_PARAMETER_CHANGE) { xl_parameter_change xlrec; /* Update our copy of the parameters in pg_control */ memcpy(&xlrec, XLogRecGetData(record), sizeof(xl_parameter_change)); LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); ControlFile->MaxConnections = xlrec.MaxConnections; ControlFile->max_prepared_xacts = xlrec.max_prepared_xacts; ControlFile->max_locks_per_xact = xlrec.max_locks_per_xact; ControlFile->wal_level = xlrec.wal_level; /* * Update minRecoveryPoint to ensure that if recovery is aborted, we * recover back up to this point before allowing hot standby again. * This is particularly important if wal_level was set to 'archive' * before, and is now 'hot_standby', to ensure you don't run queries * against the WAL preceding the wal_level change. Same applies to * decreasing max_* settings. */ minRecoveryPoint = ControlFile->minRecoveryPoint; if ((minRecoveryPoint.xlogid != 0 || minRecoveryPoint.xrecoff != 0) && XLByteLT(minRecoveryPoint, lsn)) { ControlFile->minRecoveryPoint = lsn; } UpdateControlFile(); LWLockRelease(ControlFileLock); /* Check to see if any changes to max_connections give problems */ CheckRequiredParameterValues(); } else if (info == XLOG_FPW_CHANGE) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; bool fpw; memcpy(&fpw, XLogRecGetData(record), sizeof(bool)); /* * Update the LSN of the last replayed XLOG_FPW_CHANGE record so that * do_pg_start_backup() and do_pg_stop_backup() can check whether * full_page_writes has been disabled during online backup. */ if (!fpw) { SpinLockAcquire(&xlogctl->info_lck); if (XLByteLT(xlogctl->lastFpwDisableRecPtr, ReadRecPtr)) xlogctl->lastFpwDisableRecPtr = ReadRecPtr; SpinLockRelease(&xlogctl->info_lck); } /* Keep track of full_page_writes */ lastFullPageWrites = fpw; } } void xlog_desc(StringInfo buf, uint8 xl_info, char *rec) { uint8 info = xl_info & ~XLR_INFO_MASK; if (info == XLOG_CHECKPOINT_SHUTDOWN || info == XLOG_CHECKPOINT_ONLINE) { CheckPoint *checkpoint = (CheckPoint *) rec; appendStringInfo(buf, "checkpoint: redo %X/%X; " "tli %u; fpw %s; xid %u/%u; oid %u; multi %u; offset %u; " "oldest xid %u in DB %u; oldest running xid %u; %s", checkpoint->redo.xlogid, checkpoint->redo.xrecoff, checkpoint->ThisTimeLineID, checkpoint->fullPageWrites ? "true" : "false", checkpoint->nextXidEpoch, checkpoint->nextXid, checkpoint->nextOid, checkpoint->nextMulti, checkpoint->nextMultiOffset, checkpoint->oldestXid, checkpoint->oldestXidDB, checkpoint->oldestActiveXid, (info == XLOG_CHECKPOINT_SHUTDOWN) ? "shutdown" : "online"); } else if (info == XLOG_NOOP) { appendStringInfo(buf, "xlog no-op"); } else if (info == XLOG_NEXTOID) { Oid nextOid; memcpy(&nextOid, rec, sizeof(Oid)); appendStringInfo(buf, "nextOid: %u", nextOid); } else if (info == XLOG_SWITCH) { appendStringInfo(buf, "xlog switch"); } else if (info == XLOG_RESTORE_POINT) { xl_restore_point *xlrec = (xl_restore_point *) rec; appendStringInfo(buf, "restore point: %s", xlrec->rp_name); } else if (info == XLOG_BACKUP_END) { XLogRecPtr startpoint; memcpy(&startpoint, rec, sizeof(XLogRecPtr)); appendStringInfo(buf, "backup end: %X/%X", startpoint.xlogid, startpoint.xrecoff); } else if (info == XLOG_PARAMETER_CHANGE) { xl_parameter_change xlrec; const char *wal_level_str; const struct config_enum_entry *entry; memcpy(&xlrec, rec, sizeof(xl_parameter_change)); /* Find a string representation for wal_level */ wal_level_str = "?"; for (entry = wal_level_options; entry->name; entry++) { if (entry->val == xlrec.wal_level) { wal_level_str = entry->name; break; } } appendStringInfo(buf, "parameter change: max_connections=%d max_prepared_xacts=%d max_locks_per_xact=%d wal_level=%s", xlrec.MaxConnections, xlrec.max_prepared_xacts, xlrec.max_locks_per_xact, wal_level_str); } else if (info == XLOG_FPW_CHANGE) { bool fpw; memcpy(&fpw, rec, sizeof(bool)); appendStringInfo(buf, "full_page_writes: %s", fpw ? "true" : "false"); } else appendStringInfo(buf, "UNKNOWN"); } #ifdef WAL_DEBUG static void xlog_outrec(StringInfo buf, XLogRecord *record) { int i; appendStringInfo(buf, "prev %X/%X; xid %u", record->xl_prev.xlogid, record->xl_prev.xrecoff, record->xl_xid); appendStringInfo(buf, "; len %u", record->xl_len); for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++) { if (record->xl_info & XLR_SET_BKP_BLOCK(i)) appendStringInfo(buf, "; bkpb%d", i + 1); } appendStringInfo(buf, ": %s", RmgrTable[record->xl_rmid].rm_name); } #endif /* WAL_DEBUG */ /* * Return the (possible) sync flag used for opening a file, depending on the * value of the GUC wal_sync_method. */ static int get_sync_bit(int method) { int o_direct_flag = 0; /* If fsync is disabled, never open in sync mode */ if (!enableFsync) return 0; /* * Optimize writes by bypassing kernel cache with O_DIRECT when using * O_SYNC/O_FSYNC and O_DSYNC. But only if archiving and streaming are * disabled, otherwise the archive command or walsender process will read * the WAL soon after writing it, which is guaranteed to cause a physical * read if we bypassed the kernel cache. We also skip the * posix_fadvise(POSIX_FADV_DONTNEED) call in XLogFileClose() for the same * reason. * * Never use O_DIRECT in walreceiver process for similar reasons; the WAL * written by walreceiver is normally read by the startup process soon * after its written. Also, walreceiver performs unaligned writes, which * don't work with O_DIRECT, so it is required for correctness too. */ if (!XLogIsNeeded() && !am_walreceiver) o_direct_flag = PG_O_DIRECT; switch (method) { /* * enum values for all sync options are defined even if they are * not supported on the current platform. But if not, they are * not included in the enum option array, and therefore will never * be seen here. */ case SYNC_METHOD_FSYNC: case SYNC_METHOD_FSYNC_WRITETHROUGH: case SYNC_METHOD_FDATASYNC: return 0; #ifdef OPEN_SYNC_FLAG case SYNC_METHOD_OPEN: return OPEN_SYNC_FLAG | o_direct_flag; #endif #ifdef OPEN_DATASYNC_FLAG case SYNC_METHOD_OPEN_DSYNC: return OPEN_DATASYNC_FLAG | o_direct_flag; #endif default: /* can't happen (unless we are out of sync with option array) */ elog(ERROR, "unrecognized wal_sync_method: %d", method); return 0; /* silence warning */ } } /* * GUC support */ void assign_xlog_sync_method(int new_sync_method, void *extra) { if (sync_method != new_sync_method) { /* * To ensure that no blocks escape unsynced, force an fsync on the * currently open log segment (if any). Also, if the open flag is * changing, close the log file so it will be reopened (with new flag * bit) at next use. */ if (openLogFile >= 0) { if (pg_fsync(openLogFile) != 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not fsync log file %u, segment %u: %m", openLogId, openLogSeg))); if (get_sync_bit(sync_method) != get_sync_bit(new_sync_method)) XLogFileClose(); } } } /* * Issue appropriate kind of fsync (if any) for an XLOG output file. * * 'fd' is a file descriptor for the XLOG file to be fsync'd. * 'log' and 'seg' are for error reporting purposes. */ void issue_xlog_fsync(int fd, uint32 log, uint32 seg) { switch (sync_method) { case SYNC_METHOD_FSYNC: if (pg_fsync_no_writethrough(fd) != 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not fsync log file %u, segment %u: %m", log, seg))); break; #ifdef HAVE_FSYNC_WRITETHROUGH case SYNC_METHOD_FSYNC_WRITETHROUGH: if (pg_fsync_writethrough(fd) != 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not fsync write-through log file %u, segment %u: %m", log, seg))); break; #endif #ifdef HAVE_FDATASYNC case SYNC_METHOD_FDATASYNC: if (pg_fdatasync(fd) != 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not fdatasync log file %u, segment %u: %m", log, seg))); break; #endif case SYNC_METHOD_OPEN: case SYNC_METHOD_OPEN_DSYNC: /* write synced it already */ break; default: elog(PANIC, "unrecognized wal_sync_method: %d", sync_method); break; } } /* * do_pg_start_backup is the workhorse of the user-visible pg_start_backup() * function. It creates the necessary starting checkpoint and constructs the * backup label file. * * There are two kind of backups: exclusive and non-exclusive. An exclusive * backup is started with pg_start_backup(), and there can be only one active * at a time. The backup label file of an exclusive backup is written to * $PGDATA/backup_label, and it is removed by pg_stop_backup(). * * A non-exclusive backup is used for the streaming base backups (see * src/backend/replication/basebackup.c). The difference to exclusive backups * is that the backup label file is not written to disk. Instead, its would-be * contents are returned in *labelfile, and the caller is responsible for * including it in the backup archive as 'backup_label'. There can be many * non-exclusive backups active at the same time, and they don't conflict * with an exclusive backup either. * * Every successfully started non-exclusive backup must be stopped by calling * do_pg_stop_backup() or do_pg_abort_backup(). */ XLogRecPtr do_pg_start_backup(const char *backupidstr, bool fast, char **labelfile) { bool exclusive = (labelfile == NULL); bool backup_started_in_recovery = false; XLogRecPtr checkpointloc; XLogRecPtr startpoint; pg_time_t stamp_time; char strfbuf[128]; char xlogfilename[MAXFNAMELEN]; uint32 _logId; uint32 _logSeg; struct stat stat_buf; FILE *fp; StringInfoData labelfbuf; backup_started_in_recovery = RecoveryInProgress(); if (!superuser() && !is_authenticated_user_replication_role()) ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), errmsg("must be superuser or replication role to run a backup"))); /* * Currently only non-exclusive backup can be taken during recovery. */ if (backup_started_in_recovery && exclusive) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("recovery is in progress"), errhint("WAL control functions cannot be executed during recovery."))); /* * During recovery, we don't need to check WAL level. Because, if WAL * level is not sufficient, it's impossible to get here during recovery. */ if (!backup_started_in_recovery && !XLogIsNeeded()) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("WAL level not sufficient for making an online backup"), errhint("wal_level must be set to \"archive\" or \"hot_standby\" at server start."))); if (strlen(backupidstr) > MAXPGPATH) ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("backup label too long (max %d bytes)", MAXPGPATH))); /* * Mark backup active in shared memory. We must do full-page WAL writes * during an on-line backup even if not doing so at other times, because * it's quite possible for the backup dump to obtain a "torn" (partially * written) copy of a database page if it reads the page concurrently with * our write to the same page. This can be fixed as long as the first * write to the page in the WAL sequence is a full-page write. Hence, we * turn on forcePageWrites and then force a CHECKPOINT, to ensure there * are no dirty pages in shared memory that might get dumped while the * backup is in progress without having a corresponding WAL record. (Once * the backup is complete, we need not force full-page writes anymore, * since we expect that any pages not modified during the backup interval * must have been correctly captured by the backup.) * * Note that forcePageWrites has no effect during an online backup from * the standby. * * We must hold WALInsertLock to change the value of forcePageWrites, to * ensure adequate interlocking against XLogInsert(). */ LWLockAcquire(WALInsertLock, LW_EXCLUSIVE); if (exclusive) { if (XLogCtl->Insert.exclusiveBackup) { LWLockRelease(WALInsertLock); ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("a backup is already in progress"), errhint("Run pg_stop_backup() and try again."))); } XLogCtl->Insert.exclusiveBackup = true; } else XLogCtl->Insert.nonExclusiveBackups++; XLogCtl->Insert.forcePageWrites = true; LWLockRelease(WALInsertLock); /* Ensure we release forcePageWrites if fail below */ PG_ENSURE_ERROR_CLEANUP(pg_start_backup_callback, (Datum) BoolGetDatum(exclusive)); { bool gotUniqueStartpoint = false; /* * Force an XLOG file switch before the checkpoint, to ensure that the * WAL segment the checkpoint is written to doesn't contain pages with * old timeline IDs. That would otherwise happen if you called * pg_start_backup() right after restoring from a PITR archive: the * first WAL segment containing the startup checkpoint has pages in * the beginning with the old timeline ID. That can cause trouble at * recovery: we won't have a history file covering the old timeline if * pg_xlog directory was not included in the base backup and the WAL * archive was cleared too before starting the backup. * * This also ensures that we have emitted a WAL page header that has * XLP_BKP_REMOVABLE off before we emit the checkpoint record. * Therefore, if a WAL archiver (such as pglesslog) is trying to * compress out removable backup blocks, it won't remove any that * occur after this point. * * During recovery, we skip forcing XLOG file switch, which means that * the backup taken during recovery is not available for the special * recovery case described above. */ if (!backup_started_in_recovery) RequestXLogSwitch(); do { bool checkpointfpw; /* * Force a CHECKPOINT. Aside from being necessary to prevent torn * page problems, this guarantees that two successive backup runs * will have different checkpoint positions and hence different * history file names, even if nothing happened in between. * * During recovery, establish a restartpoint if possible. We use * the last restartpoint as the backup starting checkpoint. This * means that two successive backup runs can have same checkpoint * positions. * * Since the fact that we are executing do_pg_start_backup() * during recovery means that checkpointer is running, we can use * RequestCheckpoint() to establish a restartpoint. * * We use CHECKPOINT_IMMEDIATE only if requested by user (via * passing fast = true). Otherwise this can take awhile. */ RequestCheckpoint(CHECKPOINT_FORCE | CHECKPOINT_WAIT | (fast ? CHECKPOINT_IMMEDIATE : 0)); /* * Now we need to fetch the checkpoint record location, and also * its REDO pointer. The oldest point in WAL that would be needed * to restore starting from the checkpoint is precisely the REDO * pointer. */ LWLockAcquire(ControlFileLock, LW_SHARED); checkpointloc = ControlFile->checkPoint; startpoint = ControlFile->checkPointCopy.redo; checkpointfpw = ControlFile->checkPointCopy.fullPageWrites; LWLockRelease(ControlFileLock); if (backup_started_in_recovery) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; XLogRecPtr recptr; /* * Check to see if all WAL replayed during online backup * (i.e., since last restartpoint used as backup starting * checkpoint) contain full-page writes. */ SpinLockAcquire(&xlogctl->info_lck); recptr = xlogctl->lastFpwDisableRecPtr; SpinLockRelease(&xlogctl->info_lck); if (!checkpointfpw || XLByteLE(startpoint, recptr)) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("WAL generated with full_page_writes=off was replayed " "since last restartpoint"), errhint("This means that the backup being taken on standby " "is corrupt and should not be used. " "Enable full_page_writes and run CHECKPOINT on the master, " "and then try an online backup again."))); /* * During recovery, since we don't use the end-of-backup WAL * record and don't write the backup history file, the * starting WAL location doesn't need to be unique. This means * that two base backups started at the same time might use * the same checkpoint as starting locations. */ gotUniqueStartpoint = true; } /* * If two base backups are started at the same time (in WAL sender * processes), we need to make sure that they use different * checkpoints as starting locations, because we use the starting * WAL location as a unique identifier for the base backup in the * end-of-backup WAL record and when we write the backup history * file. Perhaps it would be better generate a separate unique ID * for each backup instead of forcing another checkpoint, but * taking a checkpoint right after another is not that expensive * either because only few buffers have been dirtied yet. */ LWLockAcquire(WALInsertLock, LW_SHARED); if (XLByteLT(XLogCtl->Insert.lastBackupStart, startpoint)) { XLogCtl->Insert.lastBackupStart = startpoint; gotUniqueStartpoint = true; } LWLockRelease(WALInsertLock); } while (!gotUniqueStartpoint); XLByteToSeg(startpoint, _logId, _logSeg); XLogFileName(xlogfilename, ThisTimeLineID, _logId, _logSeg); /* * Construct backup label file */ initStringInfo(&labelfbuf); /* Use the log timezone here, not the session timezone */ stamp_time = (pg_time_t) time(NULL); pg_strftime(strfbuf, sizeof(strfbuf), "%Y-%m-%d %H:%M:%S %Z", pg_localtime(&stamp_time, log_timezone)); appendStringInfo(&labelfbuf, "START WAL LOCATION: %X/%X (file %s)\n", startpoint.xlogid, startpoint.xrecoff, xlogfilename); appendStringInfo(&labelfbuf, "CHECKPOINT LOCATION: %X/%X\n", checkpointloc.xlogid, checkpointloc.xrecoff); appendStringInfo(&labelfbuf, "BACKUP METHOD: %s\n", exclusive ? "pg_start_backup" : "streamed"); appendStringInfo(&labelfbuf, "BACKUP FROM: %s\n", backup_started_in_recovery ? "standby" : "master"); appendStringInfo(&labelfbuf, "START TIME: %s\n", strfbuf); appendStringInfo(&labelfbuf, "LABEL: %s\n", backupidstr); /* * Okay, write the file, or return its contents to caller. */ if (exclusive) { /* * Check for existing backup label --- implies a backup is already * running. (XXX given that we checked exclusiveBackup above, * maybe it would be OK to just unlink any such label file?) */ if (stat(BACKUP_LABEL_FILE, &stat_buf) != 0) { if (errno != ENOENT) ereport(ERROR, (errcode_for_file_access(), errmsg("could not stat file \"%s\": %m", BACKUP_LABEL_FILE))); } else ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("a backup is already in progress"), errhint("If you're sure there is no backup in progress, remove file \"%s\" and try again.", BACKUP_LABEL_FILE))); fp = AllocateFile(BACKUP_LABEL_FILE, "w"); if (!fp) ereport(ERROR, (errcode_for_file_access(), errmsg("could not create file \"%s\": %m", BACKUP_LABEL_FILE))); if (fwrite(labelfbuf.data, labelfbuf.len, 1, fp) != 1 || fflush(fp) != 0 || ferror(fp) || FreeFile(fp)) ereport(ERROR, (errcode_for_file_access(), errmsg("could not write file \"%s\": %m", BACKUP_LABEL_FILE))); pfree(labelfbuf.data); } else *labelfile = labelfbuf.data; } PG_END_ENSURE_ERROR_CLEANUP(pg_start_backup_callback, (Datum) BoolGetDatum(exclusive)); /* * We're done. As a convenience, return the starting WAL location. */ return startpoint; } /* Error cleanup callback for pg_start_backup */ static void pg_start_backup_callback(int code, Datum arg) { bool exclusive = DatumGetBool(arg); /* Update backup counters and forcePageWrites on failure */ LWLockAcquire(WALInsertLock, LW_EXCLUSIVE); if (exclusive) { Assert(XLogCtl->Insert.exclusiveBackup); XLogCtl->Insert.exclusiveBackup = false; } else { Assert(XLogCtl->Insert.nonExclusiveBackups > 0); XLogCtl->Insert.nonExclusiveBackups--; } if (!XLogCtl->Insert.exclusiveBackup && XLogCtl->Insert.nonExclusiveBackups == 0) { XLogCtl->Insert.forcePageWrites = false; } LWLockRelease(WALInsertLock); } /* * do_pg_stop_backup is the workhorse of the user-visible pg_stop_backup() * function. * If labelfile is NULL, this stops an exclusive backup. Otherwise this stops * the non-exclusive backup specified by 'labelfile'. */ XLogRecPtr do_pg_stop_backup(char *labelfile, bool waitforarchive) { bool exclusive = (labelfile == NULL); bool backup_started_in_recovery = false; XLogRecPtr startpoint; XLogRecPtr stoppoint; XLogRecData rdata; pg_time_t stamp_time; char strfbuf[128]; char histfilepath[MAXPGPATH]; char startxlogfilename[MAXFNAMELEN]; char stopxlogfilename[MAXFNAMELEN]; char lastxlogfilename[MAXFNAMELEN]; char histfilename[MAXFNAMELEN]; char backupfrom[20]; uint32 _logId; uint32 _logSeg; FILE *lfp; FILE *fp; char ch; int seconds_before_warning; int waits = 0; bool reported_waiting = false; char *remaining; char *ptr; backup_started_in_recovery = RecoveryInProgress(); if (!superuser() && !is_authenticated_user_replication_role()) ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be superuser or replication role to run a backup")))); /* * Currently only non-exclusive backup can be taken during recovery. */ if (backup_started_in_recovery && exclusive) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("recovery is in progress"), errhint("WAL control functions cannot be executed during recovery."))); /* * During recovery, we don't need to check WAL level. Because, if WAL * level is not sufficient, it's impossible to get here during recovery. */ if (!backup_started_in_recovery && !XLogIsNeeded()) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("WAL level not sufficient for making an online backup"), errhint("wal_level must be set to \"archive\" or \"hot_standby\" at server start."))); /* * OK to update backup counters and forcePageWrites */ LWLockAcquire(WALInsertLock, LW_EXCLUSIVE); if (exclusive) XLogCtl->Insert.exclusiveBackup = false; else { /* * The user-visible pg_start/stop_backup() functions that operate on * exclusive backups can be called at any time, but for non-exclusive * backups, it is expected that each do_pg_start_backup() call is * matched by exactly one do_pg_stop_backup() call. */ Assert(XLogCtl->Insert.nonExclusiveBackups > 0); XLogCtl->Insert.nonExclusiveBackups--; } if (!XLogCtl->Insert.exclusiveBackup && XLogCtl->Insert.nonExclusiveBackups == 0) { XLogCtl->Insert.forcePageWrites = false; } LWLockRelease(WALInsertLock); if (exclusive) { /* * Read the existing label file into memory. */ struct stat statbuf; int r; if (stat(BACKUP_LABEL_FILE, &statbuf)) { if (errno != ENOENT) ereport(ERROR, (errcode_for_file_access(), errmsg("could not stat file \"%s\": %m", BACKUP_LABEL_FILE))); ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("a backup is not in progress"))); } lfp = AllocateFile(BACKUP_LABEL_FILE, "r"); if (!lfp) { ereport(ERROR, (errcode_for_file_access(), errmsg("could not read file \"%s\": %m", BACKUP_LABEL_FILE))); } labelfile = palloc(statbuf.st_size + 1); r = fread(labelfile, statbuf.st_size, 1, lfp); labelfile[statbuf.st_size] = '\0'; /* * Close and remove the backup label file */ if (r != 1 || ferror(lfp) || FreeFile(lfp)) ereport(ERROR, (errcode_for_file_access(), errmsg("could not read file \"%s\": %m", BACKUP_LABEL_FILE))); if (unlink(BACKUP_LABEL_FILE) != 0) ereport(ERROR, (errcode_for_file_access(), errmsg("could not remove file \"%s\": %m", BACKUP_LABEL_FILE))); } /* * Read and parse the START WAL LOCATION line (this code is pretty crude, * but we are not expecting any variability in the file format). */ if (sscanf(labelfile, "START WAL LOCATION: %X/%X (file %24s)%c", &startpoint.xlogid, &startpoint.xrecoff, startxlogfilename, &ch) != 4 || ch != '\n') ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE))); remaining = strchr(labelfile, '\n') + 1; /* %n is not portable enough */ /* * Parse the BACKUP FROM line. If we are taking an online backup from the * standby, we confirm that the standby has not been promoted during the * backup. */ ptr = strstr(remaining, "BACKUP FROM:"); if (!ptr || sscanf(ptr, "BACKUP FROM: %19s\n", backupfrom) != 1) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE))); if (strcmp(backupfrom, "standby") == 0 && !backup_started_in_recovery) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("the standby was promoted during online backup"), errhint("This means that the backup being taken is corrupt " "and should not be used. " "Try taking another online backup."))); /* * During recovery, we don't write an end-of-backup record. We assume that * pg_control was backed up last and its minimum recovery point can be * available as the backup end location. Since we don't have an * end-of-backup record, we use the pg_control value to check whether * we've reached the end of backup when starting recovery from this * backup. We have no way of checking if pg_control wasn't backed up last * however. * * We don't force a switch to new WAL file and wait for all the required * files to be archived. This is okay if we use the backup to start the * standby. But, if it's for an archive recovery, to ensure all the * required files are available, a user should wait for them to be * archived, or include them into the backup. * * We return the current minimum recovery point as the backup end * location. Note that it's would be bigger than the exact backup end * location if the minimum recovery point is updated since the backup of * pg_control. This is harmless for current uses. * * XXX currently a backup history file is for informational and debug * purposes only. It's not essential for an online backup. Furthermore, * even if it's created, it will not be archived during recovery because * an archiver is not invoked. So it doesn't seem worthwhile to write a * backup history file during recovery. */ if (backup_started_in_recovery) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; XLogRecPtr recptr; /* * Check to see if all WAL replayed during online backup contain * full-page writes. */ SpinLockAcquire(&xlogctl->info_lck); recptr = xlogctl->lastFpwDisableRecPtr; SpinLockRelease(&xlogctl->info_lck); if (XLByteLE(startpoint, recptr)) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("WAL generated with full_page_writes=off was replayed " "during online backup"), errhint("This means that the backup being taken on standby " "is corrupt and should not be used. " "Enable full_page_writes and run CHECKPOINT on the master, " "and then try an online backup again."))); LWLockAcquire(ControlFileLock, LW_SHARED); stoppoint = ControlFile->minRecoveryPoint; LWLockRelease(ControlFileLock); return stoppoint; } /* * Write the backup-end xlog record */ rdata.data = (char *) (&startpoint); rdata.len = sizeof(startpoint); rdata.buffer = InvalidBuffer; rdata.next = NULL; stoppoint = XLogInsert(RM_XLOG_ID, XLOG_BACKUP_END, &rdata); /* * Force a switch to a new xlog segment file, so that the backup is valid * as soon as archiver moves out the current segment file. */ RequestXLogSwitch(); XLByteToPrevSeg(stoppoint, _logId, _logSeg); XLogFileName(stopxlogfilename, ThisTimeLineID, _logId, _logSeg); /* Use the log timezone here, not the session timezone */ stamp_time = (pg_time_t) time(NULL); pg_strftime(strfbuf, sizeof(strfbuf), "%Y-%m-%d %H:%M:%S %Z", pg_localtime(&stamp_time, log_timezone)); /* * Write the backup history file */ XLByteToSeg(startpoint, _logId, _logSeg); BackupHistoryFilePath(histfilepath, ThisTimeLineID, _logId, _logSeg, startpoint.xrecoff % XLogSegSize); fp = AllocateFile(histfilepath, "w"); if (!fp) ereport(ERROR, (errcode_for_file_access(), errmsg("could not create file \"%s\": %m", histfilepath))); fprintf(fp, "START WAL LOCATION: %X/%X (file %s)\n", startpoint.xlogid, startpoint.xrecoff, startxlogfilename); fprintf(fp, "STOP WAL LOCATION: %X/%X (file %s)\n", stoppoint.xlogid, stoppoint.xrecoff, stopxlogfilename); /* transfer remaining lines from label to history file */ fprintf(fp, "%s", remaining); fprintf(fp, "STOP TIME: %s\n", strfbuf); if (fflush(fp) || ferror(fp) || FreeFile(fp)) ereport(ERROR, (errcode_for_file_access(), errmsg("could not write file \"%s\": %m", histfilepath))); /* * Clean out any no-longer-needed history files. As a side effect, this * will post a .ready file for the newly created history file, notifying * the archiver that history file may be archived immediately. */ CleanupBackupHistory(); /* * If archiving is enabled, wait for all the required WAL files to be * archived before returning. If archiving isn't enabled, the required WAL * needs to be transported via streaming replication (hopefully with * wal_keep_segments set high enough), or some more exotic mechanism like * polling and copying files from pg_xlog with script. We have no * knowledge of those mechanisms, so it's up to the user to ensure that he * gets all the required WAL. * * We wait until both the last WAL file filled during backup and the * history file have been archived, and assume that the alphabetic sorting * property of the WAL files ensures any earlier WAL files are safely * archived as well. * * We wait forever, since archive_command is supposed to work and we * assume the admin wanted his backup to work completely. If you don't * wish to wait, you can set statement_timeout. Also, some notices are * issued to clue in anyone who might be doing this interactively. */ if (waitforarchive && XLogArchivingActive()) { XLByteToPrevSeg(stoppoint, _logId, _logSeg); XLogFileName(lastxlogfilename, ThisTimeLineID, _logId, _logSeg); XLByteToSeg(startpoint, _logId, _logSeg); BackupHistoryFileName(histfilename, ThisTimeLineID, _logId, _logSeg, startpoint.xrecoff % XLogSegSize); seconds_before_warning = 60; waits = 0; while (XLogArchiveIsBusy(lastxlogfilename) || XLogArchiveIsBusy(histfilename)) { CHECK_FOR_INTERRUPTS(); if (!reported_waiting && waits > 5) { ereport(NOTICE, (errmsg("pg_stop_backup cleanup done, waiting for required WAL segments to be archived"))); reported_waiting = true; } pg_usleep(1000000L); if (++waits >= seconds_before_warning) { seconds_before_warning *= 2; /* This wraps in >10 years... */ ereport(WARNING, (errmsg("pg_stop_backup still waiting for all required WAL segments to be archived (%d seconds elapsed)", waits), errhint("Check that your archive_command is executing properly. " "pg_stop_backup can be canceled safely, " "but the database backup will not be usable without all the WAL segments."))); } } ereport(NOTICE, (errmsg("pg_stop_backup complete, all required WAL segments have been archived"))); } else if (waitforarchive) ereport(NOTICE, (errmsg("WAL archiving is not enabled; you must ensure that all required WAL segments are copied through other means to complete the backup"))); /* * We're done. As a convenience, return the ending WAL location. */ return stoppoint; } /* * do_pg_abort_backup: abort a running backup * * This does just the most basic steps of do_pg_stop_backup(), by taking the * system out of backup mode, thus making it a lot more safe to call from * an error handler. * * NB: This is only for aborting a non-exclusive backup that doesn't write * backup_label. A backup started with pg_stop_backup() needs to be finished * with pg_stop_backup(). */ void do_pg_abort_backup(void) { LWLockAcquire(WALInsertLock, LW_EXCLUSIVE); Assert(XLogCtl->Insert.nonExclusiveBackups > 0); XLogCtl->Insert.nonExclusiveBackups--; if (!XLogCtl->Insert.exclusiveBackup && XLogCtl->Insert.nonExclusiveBackups == 0) { XLogCtl->Insert.forcePageWrites = false; } LWLockRelease(WALInsertLock); } /* * Get latest redo apply position. * * Optionally, returns the end byte position of the last restored * WAL segment. Callers not interested in that value may pass * NULL for restoreLastRecPtr. * * Exported to allow WALReceiver to read the pointer directly. */ XLogRecPtr GetXLogReplayRecPtr(XLogRecPtr *restoreLastRecPtr) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; XLogRecPtr recptr; SpinLockAcquire(&xlogctl->info_lck); recptr = xlogctl->recoveryLastRecPtr; if (restoreLastRecPtr) *restoreLastRecPtr = xlogctl->restoreLastRecPtr; SpinLockRelease(&xlogctl->info_lck); return recptr; } /* * Get current standby flush position, ie, the last WAL position * known to be fsync'd to disk in standby. */ XLogRecPtr GetStandbyFlushRecPtr(void) { XLogRecPtr receivePtr; XLogRecPtr replayPtr; XLogRecPtr restorePtr; receivePtr = GetWalRcvWriteRecPtr(NULL); replayPtr = GetXLogReplayRecPtr(&restorePtr); if (XLByteLT(receivePtr, replayPtr)) return XLByteLT(replayPtr, restorePtr) ? restorePtr : replayPtr; else return XLByteLT(receivePtr, restorePtr) ? restorePtr : receivePtr; } /* * Get latest WAL insert pointer */ XLogRecPtr GetXLogInsertRecPtr(void) { XLogCtlInsert *Insert = &XLogCtl->Insert; XLogRecPtr current_recptr; LWLockAcquire(WALInsertLock, LW_SHARED); INSERT_RECPTR(current_recptr, Insert, Insert->curridx); LWLockRelease(WALInsertLock); return current_recptr; } /* * Get latest WAL write pointer */ XLogRecPtr GetXLogWriteRecPtr(void) { { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); LogwrtResult = xlogctl->LogwrtResult; SpinLockRelease(&xlogctl->info_lck); } return LogwrtResult.Write; } /* * read_backup_label: check to see if a backup_label file is present * * If we see a backup_label during recovery, we assume that we are recovering * from a backup dump file, and we therefore roll forward from the checkpoint * identified by the label file, NOT what pg_control says. This avoids the * problem that pg_control might have been archived one or more checkpoints * later than the start of the dump, and so if we rely on it as the start * point, we will fail to restore a consistent database state. * * Returns TRUE if a backup_label was found (and fills the checkpoint * location and its REDO location into *checkPointLoc and RedoStartLSN, * respectively); returns FALSE if not. If this backup_label came from a * streamed backup, *backupEndRequired is set to TRUE. If this backup_label * was created during recovery, *backupFromStandby is set to TRUE. */ static bool read_backup_label(XLogRecPtr *checkPointLoc, bool *backupEndRequired, bool *backupFromStandby) { char startxlogfilename[MAXFNAMELEN]; TimeLineID tli; FILE *lfp; char ch; char backuptype[20]; char backupfrom[20]; *backupEndRequired = false; *backupFromStandby = false; /* * See if label file is present */ lfp = AllocateFile(BACKUP_LABEL_FILE, "r"); if (!lfp) { if (errno != ENOENT) ereport(FATAL, (errcode_for_file_access(), errmsg("could not read file \"%s\": %m", BACKUP_LABEL_FILE))); return false; /* it's not there, all is fine */ } /* * Read and parse the START WAL LOCATION and CHECKPOINT lines (this code * is pretty crude, but we are not expecting any variability in the file * format). */ if (fscanf(lfp, "START WAL LOCATION: %X/%X (file %08X%16s)%c", &RedoStartLSN.xlogid, &RedoStartLSN.xrecoff, &tli, startxlogfilename, &ch) != 5 || ch != '\n') ereport(FATAL, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE))); if (fscanf(lfp, "CHECKPOINT LOCATION: %X/%X%c", &checkPointLoc->xlogid, &checkPointLoc->xrecoff, &ch) != 3 || ch != '\n') ereport(FATAL, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("invalid data in file \"%s\"", BACKUP_LABEL_FILE))); /* * BACKUP METHOD and BACKUP FROM lines are new in 9.2. We can't restore * from an older backup anyway, but since the information on it is not * strictly required, don't error out if it's missing for some reason. */ if (fscanf(lfp, "BACKUP METHOD: %19s\n", backuptype) == 1) { if (strcmp(backuptype, "streamed") == 0) *backupEndRequired = true; } if (fscanf(lfp, "BACKUP FROM: %19s\n", backupfrom) == 1) { if (strcmp(backupfrom, "standby") == 0) *backupFromStandby = true; } if (ferror(lfp) || FreeFile(lfp)) ereport(FATAL, (errcode_for_file_access(), errmsg("could not read file \"%s\": %m", BACKUP_LABEL_FILE))); return true; } /* * Error context callback for errors occurring during rm_redo(). */ static void rm_redo_error_callback(void *arg) { XLogRecord *record = (XLogRecord *) arg; StringInfoData buf; initStringInfo(&buf); RmgrTable[record->xl_rmid].rm_desc(&buf, record->xl_info, XLogRecGetData(record)); /* don't bother emitting empty description */ if (buf.len > 0) errcontext("xlog redo %s", buf.data); pfree(buf.data); } /* * BackupInProgress: check if online backup mode is active * * This is done by checking for existence of the "backup_label" file. */ bool BackupInProgress(void) { struct stat stat_buf; return (stat(BACKUP_LABEL_FILE, &stat_buf) == 0); } /* * CancelBackup: rename the "backup_label" file to cancel backup mode * * If the "backup_label" file exists, it will be renamed to "backup_label.old". * Note that this will render an online backup in progress useless. * To correctly finish an online backup, pg_stop_backup must be called. */ void CancelBackup(void) { struct stat stat_buf; /* if the file is not there, return */ if (stat(BACKUP_LABEL_FILE, &stat_buf) < 0) return; /* remove leftover file from previously canceled backup if it exists */ unlink(BACKUP_LABEL_OLD); if (rename(BACKUP_LABEL_FILE, BACKUP_LABEL_OLD) == 0) { ereport(LOG, (errmsg("online backup mode canceled"), errdetail("\"%s\" was renamed to \"%s\".", BACKUP_LABEL_FILE, BACKUP_LABEL_OLD))); } else { ereport(WARNING, (errcode_for_file_access(), errmsg("online backup mode was not canceled"), errdetail("Could not rename \"%s\" to \"%s\": %m.", BACKUP_LABEL_FILE, BACKUP_LABEL_OLD))); } } /* * Read the XLOG page containing RecPtr into readBuf (if not read already). * Returns true if the page is read successfully. * * This is responsible for restoring files from archive as needed, as well * as for waiting for the requested WAL record to arrive in standby mode. * * 'emode' specifies the log level used for reporting "file not found" or * "end of WAL" situations in archive recovery, or in standby mode when a * trigger file is found. If set to WARNING or below, XLogPageRead() returns * false in those situations, on higher log levels the ereport() won't * return. * * In standby mode, if after a successful return of XLogPageRead() the * caller finds the record it's interested in to be broken, it should * ereport the error with the level determined by * emode_for_corrupt_record(), and then set "failedSources |= readSource" * and call XLogPageRead() again with the same arguments. This lets * XLogPageRead() to try fetching the record from another source, or to * sleep and retry. */ static bool XLogPageRead(XLogRecPtr *RecPtr, int emode, bool fetching_ckpt, bool randAccess) { static XLogRecPtr receivedUpto = {0, 0}; bool switched_segment = false; uint32 targetPageOff; uint32 targetRecOff; uint32 targetId; uint32 targetSeg; static pg_time_t last_fail_time = 0; XLByteToSeg(*RecPtr, targetId, targetSeg); targetPageOff = ((RecPtr->xrecoff % XLogSegSize) / XLOG_BLCKSZ) * XLOG_BLCKSZ; targetRecOff = RecPtr->xrecoff % XLOG_BLCKSZ; /* Fast exit if we have read the record in the current buffer already */ if (failedSources == 0 && targetId == readId && targetSeg == readSeg && targetPageOff == readOff && targetRecOff < readLen) return true; /* * See if we need to switch to a new segment because the requested record * is not in the currently open one. */ if (readFile >= 0 && !XLByteInSeg(*RecPtr, readId, readSeg)) { /* * Request a restartpoint if we've replayed too much xlog since the * last one. */ if (StandbyMode && bgwriterLaunched) { if (XLogCheckpointNeeded(readId, readSeg)) { (void) GetRedoRecPtr(); if (XLogCheckpointNeeded(readId, readSeg)) RequestCheckpoint(CHECKPOINT_CAUSE_XLOG); } } close(readFile); readFile = -1; readSource = 0; } XLByteToSeg(*RecPtr, readId, readSeg); retry: /* See if we need to retrieve more data */ if (readFile < 0 || (readSource == XLOG_FROM_STREAM && !XLByteLT(*RecPtr, receivedUpto))) { if (StandbyMode) { /* * In standby mode, wait for the requested record to become * available, either via restore_command succeeding to restore the * segment, or via walreceiver having streamed the record. */ for (;;) { if (WalRcvInProgress()) { bool havedata; /* * If we find an invalid record in the WAL streamed from * master, something is seriously wrong. There's little * chance that the problem will just go away, but PANIC is * not good for availability either, especially in hot * standby mode. Disconnect, and retry from * archive/pg_xlog again. The WAL in the archive should be * identical to what was streamed, so it's unlikely that * it helps, but one can hope... */ if (failedSources & XLOG_FROM_STREAM) { ShutdownWalRcv(); continue; } /* * Walreceiver is active, so see if new data has arrived. * * We only advance XLogReceiptTime when we obtain fresh * WAL from walreceiver and observe that we had already * processed everything before the most recent "chunk" * that it flushed to disk. In steady state where we are * keeping up with the incoming data, XLogReceiptTime will * be updated on each cycle. When we are behind, * XLogReceiptTime will not advance, so the grace time * alloted to conflicting queries will decrease. */ if (XLByteLT(*RecPtr, receivedUpto)) havedata = true; else { XLogRecPtr latestChunkStart; receivedUpto = GetWalRcvWriteRecPtr(&latestChunkStart); if (XLByteLT(*RecPtr, receivedUpto)) { havedata = true; if (!XLByteLT(*RecPtr, latestChunkStart)) { XLogReceiptTime = GetCurrentTimestamp(); SetCurrentChunkStartTime(XLogReceiptTime); } } else havedata = false; } if (havedata) { /* * Great, streamed far enough. Open the file if it's * not open already. Use XLOG_FROM_STREAM so that * source info is set correctly and XLogReceiptTime * isn't changed. */ if (readFile < 0) { readFile = XLogFileRead(readId, readSeg, PANIC, recoveryTargetTLI, XLOG_FROM_STREAM, false); Assert(readFile >= 0); switched_segment = true; } else { /* just make sure source info is correct... */ readSource = XLOG_FROM_STREAM; XLogReceiptSource = XLOG_FROM_STREAM; } break; } /* * Data not here yet, so check for trigger then sleep for * five seconds like in the WAL file polling case below. */ if (CheckForStandbyTrigger()) goto retry; /* * Wait for more WAL to arrive, or timeout to be reached */ WaitLatch(&XLogCtl->recoveryWakeupLatch, WL_LATCH_SET | WL_TIMEOUT, 5000L); ResetLatch(&XLogCtl->recoveryWakeupLatch); } else { int sources; pg_time_t now; /* * Until walreceiver manages to reconnect, poll the * archive. */ if (readFile >= 0) { close(readFile); readFile = -1; } /* Reset curFileTLI if random fetch. */ if (randAccess) curFileTLI = 0; /* * Try to restore the file from archive, or read an * existing file from pg_xlog. */ sources = XLOG_FROM_ARCHIVE | XLOG_FROM_PG_XLOG; if (!(sources & ~failedSources)) { /* * We've exhausted all options for retrieving the * file. Retry. */ failedSources = 0; /* * Before we sleep, re-scan for possible new timelines * if we were requested to recover to the latest * timeline. */ if (recoveryTargetIsLatest) { if (rescanLatestTimeLine()) continue; } /* * If it hasn't been long since last attempt, sleep to * avoid busy-waiting. */ now = (pg_time_t) time(NULL); if ((now - last_fail_time) < 5) { pg_usleep(1000000L * (5 - (now - last_fail_time))); now = (pg_time_t) time(NULL); } last_fail_time = now; /* * If primary_conninfo is set, launch walreceiver to * try to stream the missing WAL, before retrying to * restore from archive/pg_xlog. * * If fetching_ckpt is TRUE, RecPtr points to the * initial checkpoint location. In that case, we use * RedoStartLSN as the streaming start position * instead of RecPtr, so that when we later jump * backwards to start redo at RedoStartLSN, we will * have the logs streamed already. */ if (PrimaryConnInfo) { RequestXLogStreaming( fetching_ckpt ? RedoStartLSN : *RecPtr, PrimaryConnInfo); continue; } } /* Don't try to read from a source that just failed */ sources &= ~failedSources; readFile = XLogFileReadAnyTLI(readId, readSeg, DEBUG2, sources); switched_segment = true; if (readFile >= 0) break; /* * Nope, not found in archive and/or pg_xlog. */ failedSources |= sources; /* * Check to see if the trigger file exists. Note that we * do this only after failure, so when you create the * trigger file, we still finish replaying as much as we * can from archive and pg_xlog before failover. */ if (CheckForStandbyTrigger()) goto triggered; } /* * This possibly-long loop needs to handle interrupts of * startup process. */ HandleStartupProcInterrupts(); } } else { /* In archive or crash recovery. */ if (readFile < 0) { int sources; /* Reset curFileTLI if random fetch. */ if (randAccess) curFileTLI = 0; sources = XLOG_FROM_PG_XLOG; if (InArchiveRecovery) sources |= XLOG_FROM_ARCHIVE; readFile = XLogFileReadAnyTLI(readId, readSeg, emode, sources); switched_segment = true; if (readFile < 0) return false; } } } /* * At this point, we have the right segment open and if we're streaming we * know the requested record is in it. */ Assert(readFile != -1); /* * If the current segment is being streamed from master, calculate how * much of the current page we have received already. We know the * requested record has been received, but this is for the benefit of * future calls, to allow quick exit at the top of this function. */ if (readSource == XLOG_FROM_STREAM) { if (RecPtr->xlogid != receivedUpto.xlogid || (RecPtr->xrecoff / XLOG_BLCKSZ) != (receivedUpto.xrecoff / XLOG_BLCKSZ)) { readLen = XLOG_BLCKSZ; } else readLen = receivedUpto.xrecoff % XLogSegSize - targetPageOff; } else readLen = XLOG_BLCKSZ; if (switched_segment && targetPageOff != 0) { /* * Whenever switching to a new WAL segment, we read the first page of * the file and validate its header, even if that's not where the * target record is. This is so that we can check the additional * identification info that is present in the first page's "long" * header. */ readOff = 0; if (read(readFile, readBuf, XLOG_BLCKSZ) != XLOG_BLCKSZ) { ereport(emode_for_corrupt_record(emode, *RecPtr), (errcode_for_file_access(), errmsg("could not read from log file %u, segment %u, offset %u: %m", readId, readSeg, readOff))); goto next_record_is_invalid; } if (!ValidXLOGHeader((XLogPageHeader) readBuf, emode)) goto next_record_is_invalid; } /* Read the requested page */ readOff = targetPageOff; if (lseek(readFile, (off_t) readOff, SEEK_SET) < 0) { ereport(emode_for_corrupt_record(emode, *RecPtr), (errcode_for_file_access(), errmsg("could not seek in log file %u, segment %u to offset %u: %m", readId, readSeg, readOff))); goto next_record_is_invalid; } if (read(readFile, readBuf, XLOG_BLCKSZ) != XLOG_BLCKSZ) { ereport(emode_for_corrupt_record(emode, *RecPtr), (errcode_for_file_access(), errmsg("could not read from log file %u, segment %u, offset %u: %m", readId, readSeg, readOff))); goto next_record_is_invalid; } if (!ValidXLOGHeader((XLogPageHeader) readBuf, emode)) goto next_record_is_invalid; Assert(targetId == readId); Assert(targetSeg == readSeg); Assert(targetPageOff == readOff); Assert(targetRecOff < readLen); return true; next_record_is_invalid: failedSources |= readSource; if (readFile >= 0) close(readFile); readFile = -1; readLen = 0; readSource = 0; /* In standby-mode, keep trying */ if (StandbyMode) goto retry; else return false; triggered: if (readFile >= 0) close(readFile); readFile = -1; readLen = 0; readSource = 0; return false; } /* * Determine what log level should be used to report a corrupt WAL record * in the current WAL page, previously read by XLogPageRead(). * * 'emode' is the error mode that would be used to report a file-not-found * or legitimate end-of-WAL situation. Generally, we use it as-is, but if * we're retrying the exact same record that we've tried previously, only * complain the first time to keep the noise down. However, we only do when * reading from pg_xlog, because we don't expect any invalid records in archive * or in records streamed from master. Files in the archive should be complete, * and we should never hit the end of WAL because we stop and wait for more WAL * to arrive before replaying it. * * NOTE: This function remembers the RecPtr value it was last called with, * to suppress repeated messages about the same record. Only call this when * you are about to ereport(), or you might cause a later message to be * erroneously suppressed. */ static int emode_for_corrupt_record(int emode, XLogRecPtr RecPtr) { static XLogRecPtr lastComplaint = {0, 0}; if (readSource == XLOG_FROM_PG_XLOG && emode == LOG) { if (XLByteEQ(RecPtr, lastComplaint)) emode = DEBUG1; else lastComplaint = RecPtr; } return emode; } /* * Check to see whether the user-specified trigger file exists and whether a * promote request has arrived. If either condition holds, request postmaster * to shut down walreceiver, wait for it to exit, and return true. */ static bool CheckForStandbyTrigger(void) { struct stat stat_buf; static bool triggered = false; if (triggered) return true; if (IsPromoteTriggered()) { ereport(LOG, (errmsg("received promote request"))); ShutdownWalRcv(); ResetPromoteTriggered(); triggered = true; return true; } if (TriggerFile == NULL) return false; if (stat(TriggerFile, &stat_buf) == 0) { ereport(LOG, (errmsg("trigger file found: %s", TriggerFile))); ShutdownWalRcv(); unlink(TriggerFile); triggered = true; return true; } return false; } /* * Check to see if a promote request has arrived. Should be * called by postmaster after receiving SIGUSR1. */ bool CheckPromoteSignal(void) { struct stat stat_buf; if (stat(PROMOTE_SIGNAL_FILE, &stat_buf) == 0) { /* * Since we are in a signal handler, it's not safe to elog. We * silently ignore any error from unlink. */ unlink(PROMOTE_SIGNAL_FILE); return true; } return false; } /* * Wake up startup process to replay newly arrived WAL, or to notice that * failover has been requested. */ void WakeupRecovery(void) { SetLatch(&XLogCtl->recoveryWakeupLatch); } /* * Update the WalWriterSleeping flag. */ void SetWalWriterSleeping(bool sleeping) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); xlogctl->WalWriterSleeping = sleeping; SpinLockRelease(&xlogctl->info_lck); }