/*------------------------------------------------------------------------- * * xlog.c * PostgreSQL transaction log manager * * * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.303 2008/05/12 00:00:46 alvherre Exp $ * *------------------------------------------------------------------------- */ #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/xlogdefs.h" #include "access/xlogutils.h" #include "catalog/catversion.h" #include "catalog/pg_control.h" #include "catalog/pg_type.h" #include "funcapi.h" #include "miscadmin.h" #include "pgstat.h" #include "postmaster/bgwriter.h" #include "storage/bufmgr.h" #include "storage/bufpage.h" #include "storage/fd.h" #include "storage/ipc.h" #include "storage/pmsignal.h" #include "storage/procarray.h" #include "storage/smgr.h" #include "storage/spin.h" #include "utils/builtins.h" #include "utils/pg_locale.h" #include "utils/ps_status.h" /* File path names (all relative to $PGDATA) */ #define BACKUP_LABEL_FILE "backup_label" #define BACKUP_LABEL_OLD "backup_label.old" #define RECOVERY_COMMAND_FILE "recovery.conf" #define RECOVERY_COMMAND_DONE "recovery.done" /* User-settable parameters */ int CheckPointSegments = 3; int XLOGbuffers = 8; int XLogArchiveTimeout = 0; bool XLogArchiveMode = false; char *XLogArchiveCommand = NULL; char *XLOG_sync_method = NULL; const char XLOG_sync_method_default[] = DEFAULT_SYNC_METHOD_STR; bool fullPageWrites = true; bool log_checkpoints = false; #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) /* these are derived from XLOG_sync_method by assign_xlog_sync_method */ int sync_method = DEFAULT_SYNC_METHOD; static int open_sync_bit = DEFAULT_SYNC_FLAGBIT; #define XLOG_SYNC_BIT (enableFsync ? open_sync_bit : 0) /* * 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? */ bool InRecovery = false; /* 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 */ static char *recoveryRestoreCommand = NULL; static bool recoveryTarget = false; static bool recoveryTargetExact = false; static bool recoveryTargetInclusive = true; static bool recoveryLogRestartpoints = false; static TransactionId recoveryTargetXid; static TimestampTz recoveryTargetTime; static TimestampTz recoveryLastXTime = 0; /* if recoveryStopsHere returns true, it saves actual stop xid/time here */ static TransactionId recoveryStopXid; static TimestampTz recoveryStopTime; 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. * * 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 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; /*---------- * 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. * * We do a lot of pushups to minimize the amount of access to lockable * shared memory values. There are actually three shared-memory copies of * LogwrtResult, plus one unshared copy in each backend. Here's how it works: * XLogCtl->LogwrtResult is protected by info_lck * XLogCtl->Write.LogwrtResult is protected by WALWriteLock * XLogCtl->Insert.LogwrtResult is protected by WALInsertLock * One must hold the associated lock to read or write any of these, but * of course no lock is needed to read/write the unshared LogwrtResult. * * XLogCtl->LogwrtResult and XLogCtl->Write.LogwrtResult are both "always * right", since both are updated by a write or flush operation before * it releases WALWriteLock. The point of keeping XLogCtl->Write.LogwrtResult * is that it can be examined/modified by code that already holds WALWriteLock * without needing to grab info_lck as well. * * XLogCtl->Insert.LogwrtResult may lag behind the reality of the other two, * but is updated when convenient. Again, it exists for the convenience of * code that is already holding WALInsertLock but not the other locks. * * The unshared LogwrtResult may lag behind any or all of these, and again * 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. * * Note that this all works because the request and result positions can only * advance forward, never back up, and so we can easily determine which of two * values is "more up to date". * * 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 (ensures only one * checkpointer at a time; currently, with all checkpoints done by the * bgwriter, 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 { XLogwrtResult LogwrtResult; /* a recent value of LogwrtResult */ 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? */ } XLogCtlInsert; /* * Shared state data for XLogWrite/XLogFlush. */ typedef struct XLogCtlWrite { XLogwrtResult LogwrtResult; /* current value of LogwrtResult */ 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; XLogwrtResult LogwrtResult; uint32 ckptXidEpoch; /* nextXID & epoch of latest checkpoint */ TransactionId ckptXid; XLogRecPtr asyncCommitLSN; /* LSN of newest async commit */ /* Protected by WALWriteLock: */ XLogCtlWrite Write; /* * 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; 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}}; /* * 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. */ static int readFile = -1; static uint32 readId = 0; static uint32 readSeg = 0; static uint32 readOff = 0; /* 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 XLogRecord *nextRecord = NULL; static TimeLineID lastPageTLI = 0; static bool InRedo = false; static void XLogArchiveNotify(const char *xlog); static void XLogArchiveNotifySeg(uint32 log, uint32 seg); static bool XLogArchiveCheckDone(const char *xlog, bool create_if_missing); 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 CheckPointGuts(XLogRecPtr checkPointRedo, int flags); static bool XLogCheckBuffer(XLogRecData *rdata, bool doPageWrites, XLogRecPtr *lsn, BkpBlock *bkpb); static bool AdvanceXLInsertBuffer(bool new_segment); static void XLogWrite(XLogwrtRqst WriteRqst, bool flexible, bool xlog_switch); static int XLogFileInit(uint32 log, uint32 seg, bool *use_existent, bool use_lock); static bool InstallXLogFileSegment(uint32 *log, uint32 *seg, char *tmppath, bool find_free, int *max_advance, bool use_lock); static int XLogFileOpen(uint32 log, uint32 seg); static int XLogFileRead(uint32 log, uint32 seg, int emode); static void XLogFileClose(void); static bool RestoreArchivedFile(char *path, const char *xlogfname, const char *recovername, off_t expectedSize); static void PreallocXlogFiles(XLogRecPtr endptr); static void RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr); static void CleanupBackupHistory(void); static XLogRecord *ReadRecord(XLogRecPtr *RecPtr, int emode); 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 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); #ifdef WAL_DEBUG static void xlog_outrec(StringInfo buf, XLogRecord *record); #endif static void issue_xlog_fsync(void); static void pg_start_backup_callback(int code, Datum arg); static bool read_backup_label(XLogRecPtr *checkPointLoc, XLogRecPtr *minRecoveryLoc); static void rm_redo_error_callback(void *arg); /* * 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; 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); /* info's high bits are reserved for use by me */ if (info & XLR_INFO_MASK) elog(PANIC, "invalid xlog info mask %02X", 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, determine which buffers must be backed * up, and compute the CRC values for the data. Note that the record * header isn't added into the CRC initially since we don't know the final * length or info bits quite yet. Thus, the CRC will represent the CRC of * the whole record in the order "rdata, then backup blocks, then record * header". * * 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. This means we have to be careful about modifying the * rdata chain until we know we aren't going to loop back again. The only * change we allow ourselves to make earlier is to set rdt->data = NULL in * chain items we have decided we will have to back up the whole buffer * for. This is OK because we will certainly decide the same thing again * for those items if we do it over; doing it here saves an extra pass * over the chain later. */ 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, forcePageWrites could change under us, * but we'll recheck it once we have the lock. */ doPageWrites = fullPageWrites || Insert->forcePageWrites; INIT_CRC32(rdata_crc); len = 0; for (rdt = rdata;;) { if (rdt->buffer == InvalidBuffer) { /* Simple data, just include it */ len += rdt->len; COMP_CRC32(rdata_crc, rdt->data, 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; else if (rdt->data) { len += rdt->len; COMP_CRC32(rdata_crc, rdt->data, 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; } else if (rdt->data) { len += rdt->len; COMP_CRC32(rdata_crc, rdt->data, 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; } /* * Now add the backup block headers and data into the CRC */ for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++) { if (dtbuf_bkp[i]) { BkpBlock *bkpb = &(dtbuf_xlg[i]); char *page; COMP_CRC32(rdata_crc, (char *) bkpb, sizeof(BkpBlock)); page = (char *) BufferGetBlock(dtbuf[i]); if (bkpb->hole_length == 0) { COMP_CRC32(rdata_crc, page, BLCKSZ); } else { /* must skip the hole */ COMP_CRC32(rdata_crc, page, bkpb->hole_offset); COMP_CRC32(rdata_crc, page + (bkpb->hole_offset + bkpb->hole_length), BLCKSZ - (bkpb->hole_offset + bkpb->hole_length)); } } } /* * 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); 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(); goto begin; } } } } /* * Also check to see if 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->forcePageWrites && !doPageWrites) { /* Oops, must redo it with full-page data */ LWLockRelease(WALInsertLock); END_CRIT_SECTION(); goto begin; } /* * Make additional rdata chain entries for the backup blocks, so that we * don't need to special-case them in the write loop. Note that we have * now irrevocably changed the input rdata chain. 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. */ 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; } } /* * If we backed up any full blocks and online backup is not in progress, * mark the backup blocks as removable. 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. * * Note: we could just set the flag whenever !forcePageWrites, but * defining it like this leaves the info bit free for some potential other * use in records without any backup blocks. */ if ((info & XLR_BKP_BLOCK_MASK) && !Insert->forcePageWrites) info |= XLR_BKP_REMOVABLE; /* * 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->Write.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) { XLogCtlWrite *Write = &XLogCtl->Write; XLogwrtRqst FlushRqst; XLogRecPtr OldSegEnd; 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 == 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); } Write->LogwrtResult = LogwrtResult; 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) { PageHeader page; page = (PageHeader) BufferGetBlock(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 = page->pd_lsn; if (doPageWrites && XLByteLE(page->pd_lsn, RedoRecPtr)) { /* * The page needs to be backed up, so set up *bkpb */ bkpb->node = BufferGetFileNode(rdata->buffer); bkpb->block = BufferGetBlockNumber(rdata->buffer); if (rdata->buffer_std) { /* Assume we can omit data between pd_lower and pd_upper */ uint16 lower = page->pd_lower; uint16 upper = 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, bool create_if_missing) { 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 */ if (create_if_missing) XLogArchiveNotify(xlog); return false; } /* * 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; XLogCtlWrite *Write = &XLogCtl->Write; int nextidx = NextBufIdx(Insert->curridx); bool update_needed = true; XLogRecPtr OldPageRqstPtr; XLogwrtRqst WriteRqst; XLogRecPtr NewPageEndPtr; XLogPageHeader NewPage; /* Use Insert->LogwrtResult copy if it's more fresh */ if (XLByteLT(LogwrtResult.Write, Insert->LogwrtResult.Write)) LogwrtResult = Insert->LogwrtResult; /* * 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 */ if (XLByteLE(OldPageRqstPtr, LogwrtResult.Write)) { /* OK, someone wrote it already */ Insert->LogwrtResult = LogwrtResult; } else { /* Must acquire write lock */ LWLockAcquire(WALWriteLock, LW_EXCLUSIVE); LogwrtResult = Write->LogwrtResult; if (XLByteLE(OldPageRqstPtr, LogwrtResult.Write)) { /* OK, someone wrote it already */ LWLockRelease(WALWriteLock); Insert->LogwrtResult = LogwrtResult; } else { /* * Have to write buffers while holding insert lock. This is * not good, so only write as much as we absolutely must. */ WriteRqst.Write = OldPageRqstPtr; WriteRqst.Flush.xlogid = 0; WriteRqst.Flush.xrecoff = 0; XLogWrite(WriteRqst, false, false); LWLockRelease(WALWriteLock); Insert->LogwrtResult = LogwrtResult; } } } /* * 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 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. * * Caller must have just finished filling the open log file (so that * openLogId/openLogSeg are valid). We measure the distance from RedoRecPtr * to the open log file and see if that exceeds CheckPointSegments. * * Note: it is caller's responsibility that RedoRecPtr is up-to-date. */ static bool XLogCheckpointNeeded(void) { /* * 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 = (openLogId % XLogSegSize) * XLogSegsPerFile + openLogSeg; new_highbits = openLogId / 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 = Write->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(); LogwrtResult.Flush = LogwrtResult.Write; /* end of page */ if (XLogArchivingActive()) XLogArchiveNotifySeg(openLogId, openLogSeg); Write->lastSegSwitchTime = (pg_time_t) time(NULL); /* * Signal bgwriter to start 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()) { (void) GetRedoRecPtr(); if (XLogCheckpointNeeded()) 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) { 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(); } 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); } Write->LogwrtResult = LogwrtResult; } /* * Record the LSN for an asynchronous transaction commit. * (This should not be called for aborts, nor for synchronous commits.) */ void XLogSetAsyncCommitLSN(XLogRecPtr asyncCommitLSN) { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); if (XLByteLT(xlogctl->asyncCommitLSN, asyncCommitLSN)) xlogctl->asyncCommitLSN = asyncCommitLSN; SpinLockRelease(&xlogctl->info_lck); } /* * 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; /* Disabled during REDO */ if (InRedo) 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; /* read LogwrtResult and update local state */ { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; 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)) { /* now wait for the write lock */ LWLockAcquire(WALWriteLock, LW_EXCLUSIVE); LogwrtResult = XLogCtl->Write.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); } 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 has actually * happened in the field several times with 7.1 releases. Note that we * cannot get here while InRedo is true, but if the bad page is brought in * and marked dirty during recovery then CreateCheckPoint will try to * flush it at the end of recovery.) * * The current approach is to ERROR under normal conditions, but only * WARNING during recovery, so that the system can be brought up even if * there's a corrupt 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(InRecovery ? WARNING : 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. (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. */ void XLogBackgroundFlush(void) { XLogRecPtr WriteRqstPtr; bool flexible = true; /* 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->asyncCommitLSN; SpinLockRelease(&xlogctl->info_lck); flexible = false; /* ensure it all gets written */ } /* Done if already known flushed */ if (XLByteLE(WriteRqstPtr, LogwrtResult.Flush)) return; #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->Write.LogwrtResult; if (!XLByteLE(WriteRqstPtr, LogwrtResult.Flush)) { XLogwrtRqst WriteRqst; WriteRqst.Write = WriteRqstPtr; WriteRqst.Flush = WriteRqstPtr; XLogWrite(WriteRqst, flexible, false); } LWLockRelease(WALWriteLock); END_CRIT_SECTION(); } /* * Flush any previous asynchronously-committed transactions' commit records. * * NOTE: it is unwise to assume that this provides any strong guarantees. * In particular, because of the inexact LSN bookkeeping used by clog.c, * we cannot assume that hint bits will be settable for these transactions. */ void XLogAsyncCommitFlush(void) { XLogRecPtr WriteRqstPtr; /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); WriteRqstPtr = xlogctl->asyncCommitLSN; SpinLockRelease(&xlogctl->info_lck); XLogFlush(WriteRqstPtr); } /* * 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) { /* 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. */ static 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 | XLOG_SYNC_BIT, 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 XLOG_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... */ unlink(tmppath); } elog(DEBUG2, "done creating and filling new WAL file"); /* 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 | XLOG_SYNC_BIT, 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))); 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 XLOG_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 file installed, FALSE if not installed because of * exceeding max_advance limit. On Windows, we also return FALSE if we * can't rename the file into place because someone's got it open. * (Any other kind of failure causes ereport().) */ 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) ereport(ERROR, (errcode_for_file_access(), errmsg("could not link file \"%s\" to \"%s\" (initialization of log file %u, segment %u): %m", tmppath, path, *log, *seg))); unlink(tmppath); #else if (rename(tmppath, path) < 0) { #ifdef WIN32 #if !defined(__CYGWIN__) if (GetLastError() == ERROR_ACCESS_DENIED) #else if (errno == EACCES) #endif { if (use_lock) LWLockRelease(ControlFileLock); return false; } #endif /* WIN32 */ ereport(ERROR, (errcode_for_file_access(), errmsg("could not rename file \"%s\" to \"%s\" (initialization of log file %u, segment %u): %m", tmppath, path, *log, *seg))); } #endif if (use_lock) LWLockRelease(ControlFileLock); return true; } /* * Open a pre-existing logfile segment for writing. */ static int XLogFileOpen(uint32 log, uint32 seg) { char path[MAXPGPATH]; int fd; XLogFilePath(path, ThisTimeLineID, log, seg); fd = BasicOpenFile(path, O_RDWR | PG_BINARY | XLOG_SYNC_BIT, 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). */ static int XLogFileRead(uint32 log, uint32 seg, int emode) { char path[MAXPGPATH]; char xlogfname[MAXFNAMELEN]; char activitymsg[MAXFNAMELEN + 16]; 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 */ XLogFileName(xlogfname, tli, log, seg); if (InArchiveRecovery) { /* 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); } else XLogFilePath(path, tli, log, seg); 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); return fd; } if (errno != ENOENT) /* unexpected failure? */ ereport(PANIC, (errcode_for_file_access(), errmsg("could not open file \"%s\" (log file %u, segment %u): %m", path, log, seg))); } /* 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); /* * posix_fadvise is problematic on many platforms: on older x86 Linux it * just dumps core, and there are reports of problems on PPC platforms as * well. The following is therefore disabled for the time being. We could * consider some kind of configure test to see if it's safe to use, but * since we lack hard evidence that there's any useful performance gain to * be had, spending time on that seems unprofitable for now. */ #ifdef NOT_USED /* * WAL segment files will not be re-read in normal operation, so we advise * OS to release any cached pages. But do not do so if WAL archiving is * active, because archiver process could use the cache to read the WAL * segment. * * While O_DIRECT works for O_SYNC, posix_fadvise() works for fsync() and * O_SYNC, and some platforms only have posix_fadvise(). */ #if defined(HAVE_DECL_POSIX_FADVISE) && defined(POSIX_FADV_DONTNEED) if (!XLogArchivingActive()) posix_fadvise(openLogFile, 0, 0, POSIX_FADV_DONTNEED); #endif #endif /* NOT_USED */ 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; /* * 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))); /* * Copy xlog from archival storage to XLOGDIR */ rc = system(xlogRestoreCmd); if (rc == 0) { /* * command apparently succeeded, but let's make sure the file is * really there now and has the correct size. * * XXX I made wrong-size a fatal error 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 (stat(xlogpath, &stat_buf) == 0) { if (expectedSize > 0 && stat_buf.st_size != expectedSize) ereport(FATAL, (errmsg("archive file \"%s\" has wrong size: %lu instead of %lu", xlogfname, (unsigned long) stat_buf.st_size, (unsigned long) expectedSize))); 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. Aborting on other * signals such as SIGTERM seems a good idea as well. * * 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. */ signaled = WIFSIGNALED(rc) || WEXITSTATUS(rc) > 125; ereport(signaled ? FATAL : DEBUG2, (errmsg("could not restore file \"%s\" from archive: return code %d", xlogfname, rc))); /* * 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; } /* * 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++; } } /* * 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]; /* * 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); 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 (XLogArchiveCheckDone(xlde->d_name, true)) { snprintf(path, MAXPGPATH, XLOGDIR "/%s", xlde->d_name); /* * Before deleting the file, see if it can be recycled as a * future log segment. */ if (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... */ ereport(DEBUG2, (errmsg("removing transaction log file \"%s\"", xlde->d_name))); unlink(path); CheckpointStats.ckpt_segs_removed++; } XLogArchiveCleanup(xlde->d_name); } } } FreeDir(xldir); } /* * 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, true)) { 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. */ static void RestoreBkpBlocks(XLogRecord *record, XLogRecPtr lsn) { Relation reln; Buffer buffer; Page page; BkpBlock bkpb; char *blk; int i; 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); reln = XLogOpenRelation(bkpb.node); buffer = XLogReadBuffer(reln, bkpb.block, true); Assert(BufferIsValid(buffer)); page = (Page) BufferGetPage(buffer); if (bkpb.hole_length == 0) { memcpy((char *) page, blk, BLCKSZ); } else { /* must zero-fill the hole */ MemSet((char *) page, 0, BLCKSZ); memcpy((char *) page, blk, bkpb.hole_offset); 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, (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, (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, (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 or 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) { XLogRecord *record; char *buffer; XLogRecPtr tmpRecPtr = EndRecPtr; bool randAccess = false; uint32 len, total_len; uint32 targetPageOff; 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; /* fast case if next record is on same page */ if (nextRecord != NULL) { record = nextRecord; goto got_record; } /* align old recptr to next page */ if (tmpRecPtr.xrecoff % XLOG_BLCKSZ != 0) tmpRecPtr.xrecoff += (XLOG_BLCKSZ - tmpRecPtr.xrecoff % XLOG_BLCKSZ); if (tmpRecPtr.xrecoff >= XLogFileSize) { (tmpRecPtr.xlogid)++; tmpRecPtr.xrecoff = 0; } /* We will account for page header size below */ } else { 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 */ } if (readFile >= 0 && !XLByteInSeg(*RecPtr, readId, readSeg)) { close(readFile); readFile = -1; } XLByteToSeg(*RecPtr, readId, readSeg); if (readFile < 0) { /* Now it's okay to reset curFileTLI if random fetch */ if (randAccess) curFileTLI = 0; readFile = XLogFileRead(readId, readSeg, emode); if (readFile < 0) goto next_record_is_invalid; /* * 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, (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; } targetPageOff = ((RecPtr->xrecoff % XLogSegSize) / XLOG_BLCKSZ) * XLOG_BLCKSZ; if (readOff != targetPageOff) { readOff = targetPageOff; if (lseek(readFile, (off_t) readOff, SEEK_SET) < 0) { ereport(emode, (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, (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; } pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) readBuf); targetRecOff = RecPtr->xrecoff % XLOG_BLCKSZ; if (targetRecOff == 0) { /* * Can only get here in the continuing-from-prev-page case, because * XRecOffIsValid eliminated the zero-page-offset case otherwise. Need * to skip over the new page's header. */ tmpRecPtr.xrecoff += pageHeaderSize; targetRecOff = pageHeaderSize; } else if (targetRecOff < pageHeaderSize) { ereport(emode, (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, (errmsg("contrecord is requested by %X/%X", RecPtr->xlogid, RecPtr->xrecoff))); goto next_record_is_invalid; } record = (XLogRecord *) ((char *) readBuf + RecPtr->xrecoff % XLOG_BLCKSZ); got_record:; /* * 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, (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, (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, (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, (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, (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, (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, (errmsg("record length %u at %X/%X too long", total_len, RecPtr->xlogid, RecPtr->xrecoff))); goto next_record_is_invalid; } readRecordBufSize = newSize; } buffer = readRecordBuf; nextRecord = NULL; len = XLOG_BLCKSZ - RecPtr->xrecoff % XLOG_BLCKSZ; if (total_len > len) { /* Need to reassemble record */ XLogContRecord *contrecord; uint32 gotlen = len; memcpy(buffer, record, len); record = (XLogRecord *) buffer; buffer += len; for (;;) { readOff += XLOG_BLCKSZ; if (readOff >= XLogSegSize) { close(readFile); readFile = -1; NextLogSeg(readId, readSeg); readFile = XLogFileRead(readId, readSeg, emode); if (readFile < 0) goto next_record_is_invalid; readOff = 0; } if (read(readFile, readBuf, XLOG_BLCKSZ) != XLOG_BLCKSZ) { ereport(emode, (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; if (!(((XLogPageHeader) readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD)) { ereport(emode, (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, (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); if (XLOG_BLCKSZ - SizeOfXLogRecord >= pageHeaderSize + MAXALIGN(SizeOfXLogContRecord + contrecord->xl_rem_len)) { nextRecord = (XLogRecord *) ((char *) contrecord + MAXALIGN(SizeOfXLogContRecord + contrecord->xl_rem_len)); } 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; if (XLOG_BLCKSZ - SizeOfXLogRecord >= RecPtr->xrecoff % XLOG_BLCKSZ + MAXALIGN(total_len)) nextRecord = (XLogRecord *) ((char *) record + MAXALIGN(total_len)); 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; nextRecord = NULL; /* definitely not on same page */ /* * 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:; close(readFile); readFile = -1; nextRecord = NULL; 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; if (hdr->xlp_magic != XLOG_PAGE_MAGIC) { ereport(emode, (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, (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, (errmsg("WAL file is from different system"), errdetail("WAL file SYSID is %s, pg_control SYSID is %s", fhdrident_str, sysident_str))); return false; } if (longhdr->xlp_seg_size != XLogSegSize) { ereport(emode, (errmsg("WAL file is from different system"), errdetail("Incorrect XLOG_SEG_SIZE in page header."))); return false; } if (longhdr->xlp_xlog_blcksz != XLOG_BLCKSZ) { ereport(emode, (errmsg("WAL file is from different 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, (errmsg("invalid info bits %04X in log file %u, segment %u, offset %u", hdr->xlp_info, readId, readSeg, readOff))); return false; } recaddr.xlogid = readId; recaddr.xrecoff = readSeg * XLogSegSize + readOff; if (!XLByteEQ(hdr->xlp_pageaddr, recaddr)) { ereport(emode, (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, (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, (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; 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; 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; } } /* * 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 XLOG_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); snprintf(buffer, sizeof(buffer), "%s%u\t%s\t%s transaction %u at %s\n", (srcfd < 0) ? "" : "\n", parentTLI, xlogfname, recoveryStopAfter ? "after" : "before", recoveryStopXid, timestamptz_to_str(recoveryStopTime)); 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 */ char *localeptr; /* * 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; ControlFile->localeBuflen = LOCALE_NAME_BUFLEN; localeptr = setlocale(LC_COLLATE, NULL); if (!localeptr) ereport(PANIC, (errmsg("invalid LC_COLLATE setting"))); StrNCpy(ControlFile->lc_collate, localeptr, LOCALE_NAME_BUFLEN); localeptr = setlocale(LC_CTYPE, NULL); if (!localeptr) ereport(PANIC, (errmsg("invalid LC_CTYPE setting"))); StrNCpy(ControlFile->lc_ctype, localeptr, LOCALE_NAME_BUFLEN); /* 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. We do this here for 2 reasons: * * (1) if the database isn't compatible with the backend executable, we * want to abort before we can possibly do any damage; * * (2) this code is executed in the postmaster, so the setlocale() will * propagate to forked backends, which aren't going to read this file for * themselves. (These locale settings are considered critical * compatibility items because they can affect sort order of indexes.) */ 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 if (ControlFile->localeBuflen != LOCALE_NAME_BUFLEN) ereport(FATAL, (errmsg("database files are incompatible with server"), errdetail("The database cluster was initialized with LOCALE_NAME_BUFLEN %d," " but the server was compiled with LOCALE_NAME_BUFLEN %d.", ControlFile->localeBuflen, LOCALE_NAME_BUFLEN), errhint("It looks like you need to recompile or initdb."))); if (pg_perm_setlocale(LC_COLLATE, ControlFile->lc_collate) == NULL) ereport(FATAL, (errmsg("database files are incompatible with operating system"), errdetail("The database cluster was initialized with LC_COLLATE \"%s\"," " which is not recognized by setlocale().", ControlFile->lc_collate), errhint("It looks like you need to initdb or install locale support."))); if (pg_perm_setlocale(LC_CTYPE, ControlFile->lc_ctype) == NULL) ereport(FATAL, (errmsg("database files are incompatible with operating system"), errdetail("The database cluster was initialized with LC_CTYPE \"%s\"," " which is not recognized by setlocale().", ControlFile->lc_ctype), errhint("It looks like you need to initdb or install locale support."))); /* Make the fixed locale settings visible as GUC variables, too */ SetConfigOption("lc_collate", ControlFile->lc_collate, PGC_INTERNAL, PGC_S_OVERRIDE); SetConfigOption("lc_ctype", ControlFile->lc_ctype, PGC_INTERNAL, PGC_S_OVERRIDE); } 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"))); } /* * Initialization of shared memory for XLOG */ Size XLOGShmemSize(void) { Size size; /* 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->Insert.currpage = (XLogPageHeader) (XLogCtl->pages); SpinLockInit(&XLogCtl->info_lck); /* * 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 */ checkPoint.redo.xlogid = 0; checkPoint.redo.xrecoff = SizeOfXLogLongPHD; checkPoint.ThisTimeLineID = ThisTimeLineID; checkPoint.nextXidEpoch = 0; checkPoint.nextXid = FirstNormalTransactionId; checkPoint.nextOid = FirstBootstrapObjectId; checkPoint.nextMulti = FirstMultiXactId; checkPoint.nextMultiOffset = 0; checkPoint.time = (pg_time_t) time(NULL); ShmemVariableCache->nextXid = checkPoint.nextXid; ShmemVariableCache->nextOid = checkPoint.nextOid; ShmemVariableCache->oidCount = 0; MultiXactSetNextMXact(checkPoint.nextMulti, checkPoint.nextMultiOffset); /* 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 = 0; 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, 0, &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; /* 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. * * XXX longer term intention is to expand this to * cater for additional parameters and controls * possibly use a flex lexer similar to the GUC one */ static void readRecoveryCommandFile(void) { FILE *fd; char cmdline[MAXPGPATH]; TimeLineID rtli = 0; bool rtliGiven = false; bool syntaxError = false; 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))); } ereport(LOG, (errmsg("starting archive recovery"))); /* * Parse the file... */ while (fgets(cmdline, sizeof(cmdline), fd) != NULL) { /* skip leading whitespace and check for # comment */ char *ptr; char *tok1; char *tok2; for (ptr = cmdline; *ptr; ptr++) { if (!isspace((unsigned char) *ptr)) break; } if (*ptr == '\0' || *ptr == '#') continue; /* identify the quoted parameter value */ tok1 = strtok(ptr, "'"); if (!tok1) { syntaxError = true; break; } tok2 = strtok(NULL, "'"); if (!tok2) { syntaxError = true; break; } /* reparse to get just the parameter name */ tok1 = strtok(ptr, " \t="); if (!tok1) { syntaxError = true; break; } if (strcmp(tok1, "restore_command") == 0) { recoveryRestoreCommand = pstrdup(tok2); ereport(LOG, (errmsg("restore_command = '%s'", recoveryRestoreCommand))); } else if (strcmp(tok1, "recovery_target_timeline") == 0) { rtliGiven = true; if (strcmp(tok2, "latest") == 0) rtli = 0; else { errno = 0; rtli = (TimeLineID) strtoul(tok2, NULL, 0); if (errno == EINVAL || errno == ERANGE) ereport(FATAL, (errmsg("recovery_target_timeline is not a valid number: \"%s\"", tok2))); } if (rtli) ereport(LOG, (errmsg("recovery_target_timeline = %u", rtli))); else ereport(LOG, (errmsg("recovery_target_timeline = latest"))); } else if (strcmp(tok1, "recovery_target_xid") == 0) { errno = 0; recoveryTargetXid = (TransactionId) strtoul(tok2, NULL, 0); if (errno == EINVAL || errno == ERANGE) ereport(FATAL, (errmsg("recovery_target_xid is not a valid number: \"%s\"", tok2))); ereport(LOG, (errmsg("recovery_target_xid = %u", recoveryTargetXid))); recoveryTarget = true; recoveryTargetExact = true; } else if (strcmp(tok1, "recovery_target_time") == 0) { /* * if recovery_target_xid specified, then this overrides * recovery_target_time */ if (recoveryTargetExact) continue; recoveryTarget = true; recoveryTargetExact = false; /* * Convert the time string given by the user to TimestampTz form. */ recoveryTargetTime = DatumGetTimestampTz(DirectFunctionCall3(timestamptz_in, CStringGetDatum(tok2), ObjectIdGetDatum(InvalidOid), Int32GetDatum(-1))); ereport(LOG, (errmsg("recovery_target_time = '%s'", timestamptz_to_str(recoveryTargetTime)))); } else if (strcmp(tok1, "recovery_target_inclusive") == 0) { /* * does nothing if a recovery_target is not also set */ if (strcmp(tok2, "true") == 0) recoveryTargetInclusive = true; else { recoveryTargetInclusive = false; tok2 = "false"; } ereport(LOG, (errmsg("recovery_target_inclusive = %s", tok2))); } else if (strcmp(tok1, "log_restartpoints") == 0) { /* * does nothing if a recovery_target is not also set */ if (strcmp(tok2, "true") == 0) recoveryLogRestartpoints = true; else { recoveryLogRestartpoints = false; tok2 = "false"; } ereport(LOG, (errmsg("log_restartpoints = %s", tok2))); } else ereport(FATAL, (errmsg("unrecognized recovery parameter \"%s\"", tok1))); } FreeFile(fd); if (syntaxError) ereport(FATAL, (errmsg("syntax error in recovery command file: %s", cmdline), errhint("Lines should have the format parameter = 'value'."))); /* Check that required parameters were supplied */ if (recoveryRestoreCommand == NULL) ereport(FATAL, (errmsg("recovery command file \"%s\" did not specify restore_command", 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; } else { /* We start the "latest" search from pg_control's timeline */ recoveryTargetTLI = findNewestTimeLine(recoveryTargetTLI); } } } /* * 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; /* * We should have the ending log segment currently open. Verify, and then * close it (to avoid problems on Windows with trying to rename or delete * an open file). */ Assert(readFile >= 0); Assert(readId == endLogId); Assert(readSeg == endLogSeg); close(readFile); readFile = -1; /* * If the segment was fetched from archival storage, we want to replace * the existing xlog segment (if any) with the archival version. This is * because whatever is in XLOGDIR is very possibly older than what we have * from the archives, since it could have come from restoring a PGDATA * backup. In any case, the archival version certainly is more * descriptive of what our current database state is, because that is what * we replayed from. * * Note that if we are establishing a new timeline, ThisTimeLineID is * already set to the new value, and so we will create a new file instead * of overwriting any existing file. (This is, in fact, always the case * at present.) */ snprintf(recoveryPath, MAXPGPATH, XLOGDIR "/RECOVERYXLOG"); XLogFilePath(xlogpath, ThisTimeLineID, endLogId, endLogSeg); if (restoredFromArchive) { ereport(DEBUG3, (errmsg_internal("moving last restored xlog to \"%s\"", xlogpath))); unlink(xlogpath); /* might or might not exist */ if (rename(recoveryPath, xlogpath) != 0) ereport(FATAL, (errcode_for_file_access(), errmsg("could not rename file \"%s\" to \"%s\": %m", recoveryPath, xlogpath))); /* XXX might we need to fix permissions on the file? */ } else { /* * If the latest segment is not archival, but there's still a * RECOVERYXLOG laying about, get rid of it. */ unlink(recoveryPath); /* ignore any error */ /* * 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. */ if (endTLI != ThisTimeLineID) XLogFileCopy(endLogId, endLogSeg, endTLI, endLogId, endLogSeg); } /* * 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); /* 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. * 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; /* We only consider stopping at COMMIT or ABORT records */ if (record->xl_rmid != RM_XACT_ID) return false; record_info = record->xl_info & ~XLR_INFO_MASK; if (record_info == XLOG_XACT_COMMIT) { xl_xact_commit *recordXactCommitData; recordXactCommitData = (xl_xact_commit *) XLogRecGetData(record); recordXtime = recordXactCommitData->xact_time; } else if (record_info == XLOG_XACT_ABORT) { xl_xact_abort *recordXactAbortData; recordXactAbortData = (xl_xact_abort *) XLogRecGetData(record); recordXtime = recordXactAbortData->xact_time; } else return false; /* Remember the most recent COMMIT/ABORT time for logging purposes */ recoveryLastXTime = recordXtime; /* Do we have a PITR target at all? */ if (!recoveryTarget) return false; if (recoveryTargetExact) { /* * 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 { /* * 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) { 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 (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)))); } } return stopsHere; } /* * 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, LastRec, checkPointLoc, minRecoveryLoc, EndOfLog; uint32 endLogId; uint32 endLogSeg; XLogRecord *record; uint32 freespace; TransactionId oldestActiveXID; /* * 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_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 /* * 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))); if (read_backup_label(&checkPointLoc, &minRecoveryLoc)) { /* * 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) { ereport(DEBUG1, (errmsg("checkpoint record is at %X/%X", checkPointLoc.xlogid, checkPointLoc.xrecoff))); InRecovery = true; /* force recovery even if SHUTDOWNED */ } else { ereport(PANIC, (errmsg("could not locate required checkpoint record"), errhint("If you are not restoring from a backup, try removing the file \"%s/backup_label\".", DataDir))); } /* 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; record = ReadCheckpointRecord(checkPointLoc, 1); if (record != NULL) { ereport(DEBUG1, (errmsg("checkpoint record is at %X/%X", checkPointLoc.xlogid, checkPointLoc.xrecoff))); } 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"))); } } LastRec = RecPtr = checkPointLoc; memcpy(&checkPoint, XLogRecGetData(record), sizeof(CheckPoint)); wasShutdown = (record->xl_info == XLOG_CHECKPOINT_SHUTDOWN); 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))); 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); /* * 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; 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; /* * 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. */ if (InArchiveRecovery) { ereport(LOG, (errmsg("automatic recovery in progress"))); 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 (minRecoveryLoc.xlogid != 0 || minRecoveryLoc.xrecoff != 0) ControlFile->minRecoveryPoint = minRecoveryLoc; ControlFile->time = (pg_time_t) time(NULL); UpdateControlFile(); /* * 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))); } /* Start up the recovery environment */ XLogInitRelationCache(); for (rmid = 0; rmid <= RM_MAX_ID; rmid++) { if (RmgrTable[rmid].rm_startup != NULL) RmgrTable[rmid].rm_startup(); } /* * 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); } else { /* just have to read next record after CheckPoint */ record = ReadRecord(NULL, LOG); } if (record != NULL) { bool recoveryContinue = true; bool recoveryApply = true; ErrorContextCallback errcontext; 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) { 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 /* * Have we reached our recovery target? */ if (recoveryStopsHere(record, &recoveryApply)) { 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; /* nextXid must be beyond record's xid */ if (TransactionIdFollowsOrEquals(record->xl_xid, ShmemVariableCache->nextXid)) { ShmemVariableCache->nextXid = record->xl_xid; TransactionIdAdvance(ShmemVariableCache->nextXid); } if (record->xl_info & XLR_BKP_BLOCK_MASK) RestoreBkpBlocks(record, EndRecPtr); RmgrTable[record->xl_rmid].rm_redo(EndRecPtr, record); /* Pop the error context stack */ error_context_stack = errcontext.previous; LastRec = ReadRecPtr; record = ReadRecord(NULL, LOG); } while (record != NULL && recoveryContinue); /* * end of main redo apply loop */ ereport(LOG, (errmsg("redo done at %X/%X", ReadRecPtr.xlogid, ReadRecPtr.xrecoff))); if (recoveryLastXTime) ereport(LOG, (errmsg("last completed transaction was at log time %s", timestamptz_to_str(recoveryLastXTime)))); InRedo = false; } else { /* there are no WAL records following the checkpoint */ ereport(LOG, (errmsg("redo is not required"))); } } /* * 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); EndOfLog = EndRecPtr; XLByteToPrevSeg(EndOfLog, endLogId, endLogSeg); /* * Complain if we did not roll forward far enough to render the backup * dump consistent. */ if (XLByteLT(EndOfLog, ControlFile->minRecoveryPoint)) { if (reachedStopPoint) /* stopped because of stop request */ ereport(FATAL, (errmsg("requested recovery stop point is before end time of backup dump"))); else /* ran off end of WAL */ ereport(FATAL, (errmsg("WAL ends before end time of backup dump"))); } /* * 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->Write.LogwrtResult = LogwrtResult; Insert->LogwrtResult = LogwrtResult; 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 Write.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(); if (InRecovery) { int rmid; /* * 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(); } /* * Check to see if the XLOG sequence contained any unresolved * references to uninitialized pages. */ XLogCheckInvalidPages(); /* * Reset pgstat data, because it may be invalid after recovery. */ pgstat_reset_all(); /* * 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. */ CreateCheckPoint(CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_IMMEDIATE); /* * Close down recovery environment */ XLogCloseRelationCache(); } /* * Preallocate additional log files, if wanted. */ PreallocXlogFiles(EndOfLog); /* * Okay, we're officially UP. */ InRecovery = false; ControlFile->state = DB_IN_PRODUCTION; ControlFile->time = (pg_time_t) time(NULL); UpdateControlFile(); /* start the archive_timeout timer running */ XLogCtl->Write.lastSegSwitchTime = ControlFile->time; /* initialize shared-memory copy of latest checkpoint XID/epoch */ XLogCtl->ckptXidEpoch = ControlFile->checkPointCopy.nextXidEpoch; XLogCtl->ckptXid = ControlFile->checkPointCopy.nextXid; /* also initialize latestCompletedXid, to nextXid - 1 */ ShmemVariableCache->latestCompletedXid = ShmemVariableCache->nextXid; TransactionIdRetreat(ShmemVariableCache->latestCompletedXid); /* Start up the commit log and related stuff, too */ StartupCLOG(); StartupSUBTRANS(oldestActiveXID); StartupMultiXact(); /* Reload shared-memory state for prepared transactions */ RecoverPreparedTransactions(); /* 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; } } /* * 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); 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; /* 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; } /* * 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; } /* * This must be called ONCE during postmaster or standalone-backend shutdown */ void ShutdownXLOG(int code, Datum arg) { ereport(LOG, (errmsg("shutting down"))); 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) { elog(LOG, "checkpoint starting:%s%s%s%s%s%s", (flags & CHECKPOINT_IS_SHUTDOWN) ? " shutdown" : "", (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(void) { long write_secs, sync_secs, total_secs; int write_usecs, sync_usecs, total_usecs; CheckpointStats.ckpt_end_t = GetCurrentTimestamp(); TimestampDifference(CheckpointStats.ckpt_start_t, CheckpointStats.ckpt_end_t, &total_secs, &total_usecs); 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); 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", 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); } /* * 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_IMMEDIATE: finish the checkpoint ASAP, * ignoring checkpoint_completion_target parameter. * CHECKPOINT_FORCE: force a checkpoint even if no XLOG activity has occured * since the last one (implied by CHECKPOINT_IS_SHUTDOWN). * * 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 = (flags & CHECKPOINT_IS_SHUTDOWN) != 0; CheckPoint checkPoint; XLogRecPtr recptr; XLogCtlInsert *Insert = &XLogCtl->Insert; XLogRecData rdata; uint32 freespace; uint32 _logId; uint32 _logSeg; TransactionId *inCommitXids; int nInCommit; /* * 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) { ControlFile->state = DB_SHUTDOWNING; ControlFile->time = (pg_time_t) time(NULL); UpdateControlFile(); } /* * 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.ThisTimeLineID = ThisTimeLineID; checkPoint.time = (pg_time_t) time(NULL); /* * 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_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; } } /* * 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); /* * 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; 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); 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 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); 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). */ if (_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 (!InRecovery) TruncateSUBTRANS(GetOldestXmin(true, false)); /* All real work is done, but log before releasing lock. */ if (log_checkpoints) LogCheckpointEnd(); 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(); CheckPointBuffers(flags); /* performs all required fsyncs */ /* We deliberately delay 2PC checkpointing as long as possible */ CheckPointTwoPhase(checkPointRedo); } /* * Set a recovery restart point if appropriate * * 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. This function is called each time * a checkpoint record is read from XLOG; it must determine whether a * restartpoint is needed or not. */ static void RecoveryRestartPoint(const CheckPoint *checkPoint) { int elapsed_secs; int rmid; /* * Do nothing if the elapsed time since the last restartpoint is less than * half of checkpoint_timeout. (We use a value less than * checkpoint_timeout so that variations in the timing of checkpoints on * the master, or speed of transmission of WAL segments to a slave, won't * make the slave skip a restartpoint once it's synced with the master.) * Checking true elapsed time keeps us from doing restartpoints too often * while rapidly scanning large amounts of WAL. */ elapsed_secs = (pg_time_t) time(NULL) - ControlFile->time; if (elapsed_secs < CheckPointTimeout / 2) return; /* * Is it safe to checkpoint? 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(DEBUG2, "RM %d not safe to record restart point at %X/%X", rmid, checkPoint->redo.xlogid, checkPoint->redo.xrecoff); return; } } /* * OK, force data out to disk */ CheckPointGuts(checkPoint->redo, CHECKPOINT_IMMEDIATE); /* * Update pg_control so that any subsequent crash will restart from this * checkpoint. Note: ReadRecPtr gives the XLOG address of the checkpoint * record itself. */ ControlFile->prevCheckPoint = ControlFile->checkPoint; ControlFile->checkPoint = ReadRecPtr; ControlFile->checkPointCopy = *checkPoint; ControlFile->time = (pg_time_t) time(NULL); UpdateControlFile(); ereport((recoveryLogRestartpoints ? LOG : DEBUG2), (errmsg("recovery restart point at %X/%X", checkPoint->redo.xlogid, checkPoint->redo.xrecoff))); if (recoveryLastXTime) ereport((recoveryLogRestartpoints ? LOG : DEBUG2), (errmsg("last completed transaction was at log time %s", timestamptz_to_str(recoveryLastXTime)))); } /* * 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; } /* * XLOG resource manager's routines */ void xlog_redo(XLogRecPtr lsn, XLogRecord *record) { uint8 info = record->xl_info & ~XLR_INFO_MASK; if (info == XLOG_NEXTOID) { Oid nextOid; memcpy(&nextOid, XLogRecGetData(record), sizeof(Oid)); if (ShmemVariableCache->nextOid < nextOid) { ShmemVariableCache->nextOid = nextOid; ShmemVariableCache->oidCount = 0; } } else if (info == XLOG_CHECKPOINT_SHUTDOWN) { CheckPoint checkPoint; memcpy(&checkPoint, XLogRecGetData(record), sizeof(CheckPoint)); /* In a SHUTDOWN checkpoint, believe the counters exactly */ ShmemVariableCache->nextXid = checkPoint.nextXid; ShmemVariableCache->nextOid = checkPoint.nextOid; ShmemVariableCache->oidCount = 0; MultiXactSetNextMXact(checkPoint.nextMulti, checkPoint.nextMultiOffset); /* ControlFile->checkPointCopy always tracks the latest ckpt XID */ ControlFile->checkPointCopy.nextXidEpoch = checkPoint.nextXidEpoch; ControlFile->checkPointCopy.nextXid = checkPoint.nextXid; /* * 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 counters like NEXTOID */ if (TransactionIdPrecedes(ShmemVariableCache->nextXid, checkPoint.nextXid)) ShmemVariableCache->nextXid = checkPoint.nextXid; if (ShmemVariableCache->nextOid < checkPoint.nextOid) { ShmemVariableCache->nextOid = checkPoint.nextOid; ShmemVariableCache->oidCount = 0; } MultiXactAdvanceNextMXact(checkPoint.nextMulti, checkPoint.nextMultiOffset); /* ControlFile->checkPointCopy always tracks the latest ckpt XID */ ControlFile->checkPointCopy.nextXidEpoch = checkPoint.nextXidEpoch; ControlFile->checkPointCopy.nextXid = checkPoint.nextXid; /* 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 */ } } 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; xid %u/%u; oid %u; multi %u; offset %u; %s", checkpoint->redo.xlogid, checkpoint->redo.xrecoff, checkpoint->ThisTimeLineID, checkpoint->nextXidEpoch, checkpoint->nextXid, checkpoint->nextOid, checkpoint->nextMulti, checkpoint->nextMultiOffset, (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 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); 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 */ /* * GUC support */ const char * assign_xlog_sync_method(const char *method, bool doit, GucSource source) { int new_sync_method; int new_sync_bit; if (pg_strcasecmp(method, "fsync") == 0) { new_sync_method = SYNC_METHOD_FSYNC; new_sync_bit = 0; } #ifdef HAVE_FSYNC_WRITETHROUGH else if (pg_strcasecmp(method, "fsync_writethrough") == 0) { new_sync_method = SYNC_METHOD_FSYNC_WRITETHROUGH; new_sync_bit = 0; } #endif #ifdef HAVE_FDATASYNC else if (pg_strcasecmp(method, "fdatasync") == 0) { new_sync_method = SYNC_METHOD_FDATASYNC; new_sync_bit = 0; } #endif #ifdef OPEN_SYNC_FLAG else if (pg_strcasecmp(method, "open_sync") == 0) { new_sync_method = SYNC_METHOD_OPEN; new_sync_bit = OPEN_SYNC_FLAG; } #endif #ifdef OPEN_DATASYNC_FLAG else if (pg_strcasecmp(method, "open_datasync") == 0) { new_sync_method = SYNC_METHOD_OPEN; new_sync_bit = OPEN_DATASYNC_FLAG; } #endif else return NULL; if (!doit) return method; if (sync_method != new_sync_method || open_sync_bit != new_sync_bit) { /* * 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 (open_sync_bit != new_sync_bit) XLogFileClose(); } sync_method = new_sync_method; open_sync_bit = new_sync_bit; } return method; } /* * Issue appropriate kind of fsync (if any) on the current XLOG output file */ static void issue_xlog_fsync(void) { switch (sync_method) { case SYNC_METHOD_FSYNC: if (pg_fsync_no_writethrough(openLogFile) != 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not fsync log file %u, segment %u: %m", openLogId, openLogSeg))); break; #ifdef HAVE_FSYNC_WRITETHROUGH case SYNC_METHOD_FSYNC_WRITETHROUGH: if (pg_fsync_writethrough(openLogFile) != 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not fsync write-through log file %u, segment %u: %m", openLogId, openLogSeg))); break; #endif #ifdef HAVE_FDATASYNC case SYNC_METHOD_FDATASYNC: if (pg_fdatasync(openLogFile) != 0) ereport(PANIC, (errcode_for_file_access(), errmsg("could not fdatasync log file %u, segment %u: %m", openLogId, openLogSeg))); break; #endif case SYNC_METHOD_OPEN: /* write synced it already */ break; default: elog(PANIC, "unrecognized wal_sync_method: %d", sync_method); break; } } /* * pg_start_backup: set up for taking an on-line backup dump * * Essentially what this does is to create a backup label file in $PGDATA, * where it will be archived as part of the backup dump. The label file * contains the user-supplied label string (typically this would be used * to tell where the backup dump will be stored) and the starting time and * starting WAL location for the dump. */ Datum pg_start_backup(PG_FUNCTION_ARGS) { text *backupid = PG_GETARG_TEXT_P(0); char *backupidstr; 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; if (!superuser()) ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), errmsg("must be superuser to run a backup"))); if (!XLogArchivingActive()) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("WAL archiving is not active"), errhint("archive_mode must be enabled at server start."))); if (!XLogArchiveCommandSet()) ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("WAL archiving is not active"), errhint("archive_command must be defined before " "online backups can be made safely."))); backupidstr = text_to_cstring(backupid); /* * 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.) * * We must hold WALInsertLock to change the value of forcePageWrites, to * ensure adequate interlocking against XLogInsert(). */ LWLockAcquire(WALInsertLock, LW_EXCLUSIVE); if (XLogCtl->Insert.forcePageWrites) { 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.forcePageWrites = true; LWLockRelease(WALInsertLock); /* Ensure we release forcePageWrites if fail below */ PG_ENSURE_ERROR_CLEANUP(pg_start_backup_callback, (Datum) 0); { /* * 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. * * We don't use CHECKPOINT_IMMEDIATE, hence this can take awhile. */ RequestCheckpoint(CHECKPOINT_FORCE | CHECKPOINT_WAIT); /* * 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_EXCLUSIVE); checkpointloc = ControlFile->checkPoint; startpoint = ControlFile->checkPointCopy.redo; LWLockRelease(ControlFileLock); XLByteToSeg(startpoint, _logId, _logSeg); XLogFileName(xlogfilename, 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)); /* * Check for existing backup label --- implies a backup is already * running. (XXX given that we checked forcePageWrites 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))); /* * Okay, write the 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))); fprintf(fp, "START WAL LOCATION: %X/%X (file %s)\n", startpoint.xlogid, startpoint.xrecoff, xlogfilename); fprintf(fp, "CHECKPOINT LOCATION: %X/%X\n", checkpointloc.xlogid, checkpointloc.xrecoff); fprintf(fp, "START TIME: %s\n", strfbuf); fprintf(fp, "LABEL: %s\n", backupidstr); if (fflush(fp) || ferror(fp) || FreeFile(fp)) ereport(ERROR, (errcode_for_file_access(), errmsg("could not write file \"%s\": %m", BACKUP_LABEL_FILE))); } PG_END_ENSURE_ERROR_CLEANUP(pg_start_backup_callback, (Datum) 0); /* * We're done. As a convenience, return the starting WAL location. */ snprintf(xlogfilename, sizeof(xlogfilename), "%X/%X", startpoint.xlogid, startpoint.xrecoff); PG_RETURN_TEXT_P(cstring_to_text(xlogfilename)); } /* Error cleanup callback for pg_start_backup */ static void pg_start_backup_callback(int code, Datum arg) { /* Turn off forcePageWrites on failure */ LWLockAcquire(WALInsertLock, LW_EXCLUSIVE); XLogCtl->Insert.forcePageWrites = false; LWLockRelease(WALInsertLock); } /* * pg_stop_backup: finish taking an on-line backup dump * * We remove the backup label file created by pg_start_backup, and instead * create a backup history file in pg_xlog (whence it will immediately be * archived). The backup history file contains the same info found in * the label file, plus the backup-end time and WAL location. * Note: different from CancelBackup which just cancels online backup mode. */ Datum pg_stop_backup(PG_FUNCTION_ARGS) { XLogRecPtr startpoint; XLogRecPtr stoppoint; pg_time_t stamp_time; char strfbuf[128]; char histfilepath[MAXPGPATH]; char startxlogfilename[MAXFNAMELEN]; char stopxlogfilename[MAXFNAMELEN]; uint32 _logId; uint32 _logSeg; FILE *lfp; FILE *fp; char ch; int ich; int seconds_before_warning; int waits = 0; if (!superuser()) ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be superuser to run a backup")))); /* * OK to clear forcePageWrites */ LWLockAcquire(WALInsertLock, LW_EXCLUSIVE); XLogCtl->Insert.forcePageWrites = false; LWLockRelease(WALInsertLock); /* * 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. We'll report * the end address of the XLOG SWITCH record as the backup stopping point. */ stoppoint = RequestXLogSwitch(); XLByteToSeg(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)); /* * Open the existing label file */ lfp = AllocateFile(BACKUP_LABEL_FILE, "r"); if (!lfp) { if (errno != ENOENT) ereport(ERROR, (errcode_for_file_access(), errmsg("could not read file \"%s\": %m", BACKUP_LABEL_FILE))); ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("a backup is not in progress"))); } /* * 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 (fscanf(lfp, "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))); /* * 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 */ while ((ich = fgetc(lfp)) != EOF) fputc(ich, fp); 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))); /* * Close and remove the backup label file */ if (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))); /* * 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(); /* * Wait until the history file has been archived. We assume that the * alphabetic sorting property of the WAL files ensures the last WAL * file is guaranteed archived by the time the history file is archived. * * 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 = xx; * * If the status file is missing, we assume that is because it was * set to .ready before we slept, then while asleep it has been set * to .done and then removed by a concurrent checkpoint. */ BackupHistoryFileName(histfilepath, ThisTimeLineID, _logId, _logSeg, startpoint.xrecoff % XLogSegSize); seconds_before_warning = 60; waits = 0; while (!XLogArchiveCheckDone(histfilepath, false)) { CHECK_FOR_INTERRUPTS(); pg_usleep(1000000L); if (++waits >= seconds_before_warning) { seconds_before_warning *= 2; /* This wraps in >10 years... */ elog(WARNING, "pg_stop_backup() waiting for archive to complete " "(%d seconds delay)", waits); } } /* * We're done. As a convenience, return the ending WAL location. */ snprintf(stopxlogfilename, sizeof(stopxlogfilename), "%X/%X", stoppoint.xlogid, stoppoint.xrecoff); PG_RETURN_TEXT_P(cstring_to_text(stopxlogfilename)); } /* * pg_switch_xlog: switch to next xlog file */ Datum pg_switch_xlog(PG_FUNCTION_ARGS) { XLogRecPtr switchpoint; char location[MAXFNAMELEN]; if (!superuser()) ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be superuser to switch transaction log files")))); switchpoint = RequestXLogSwitch(); /* * As a convenience, return the WAL location of the switch record */ snprintf(location, sizeof(location), "%X/%X", switchpoint.xlogid, switchpoint.xrecoff); PG_RETURN_TEXT_P(cstring_to_text(location)); } /* * Report the current WAL write location (same format as pg_start_backup etc) * * This is useful for determining how much of WAL is visible to an external * archiving process. Note that the data before this point is written out * to the kernel, but is not necessarily synced to disk. */ Datum pg_current_xlog_location(PG_FUNCTION_ARGS) { char location[MAXFNAMELEN]; /* Make sure we have an up-to-date local LogwrtResult */ { /* use volatile pointer to prevent code rearrangement */ volatile XLogCtlData *xlogctl = XLogCtl; SpinLockAcquire(&xlogctl->info_lck); LogwrtResult = xlogctl->LogwrtResult; SpinLockRelease(&xlogctl->info_lck); } snprintf(location, sizeof(location), "%X/%X", LogwrtResult.Write.xlogid, LogwrtResult.Write.xrecoff); PG_RETURN_TEXT_P(cstring_to_text(location)); } /* * Report the current WAL insert location (same format as pg_start_backup etc) * * This function is mostly for debugging purposes. */ Datum pg_current_xlog_insert_location(PG_FUNCTION_ARGS) { XLogCtlInsert *Insert = &XLogCtl->Insert; XLogRecPtr current_recptr; char location[MAXFNAMELEN]; /* * Get the current end-of-WAL position ... shared lock is sufficient */ LWLockAcquire(WALInsertLock, LW_SHARED); INSERT_RECPTR(current_recptr, Insert, Insert->curridx); LWLockRelease(WALInsertLock); snprintf(location, sizeof(location), "%X/%X", current_recptr.xlogid, current_recptr.xrecoff); PG_RETURN_TEXT_P(cstring_to_text(location)); } /* * Compute an xlog file name and decimal byte offset given a WAL location, * such as is returned by pg_stop_backup() or pg_xlog_switch(). * * Note that a location exactly at a segment boundary is taken to be in * the previous segment. This is usually the right thing, since the * expected usage is to determine which xlog file(s) are ready to archive. */ Datum pg_xlogfile_name_offset(PG_FUNCTION_ARGS) { text *location = PG_GETARG_TEXT_P(0); char *locationstr; unsigned int uxlogid; unsigned int uxrecoff; uint32 xlogid; uint32 xlogseg; uint32 xrecoff; XLogRecPtr locationpoint; char xlogfilename[MAXFNAMELEN]; Datum values[2]; bool isnull[2]; TupleDesc resultTupleDesc; HeapTuple resultHeapTuple; Datum result; /* * Read input and parse */ locationstr = text_to_cstring(location); if (sscanf(locationstr, "%X/%X", &uxlogid, &uxrecoff) != 2) ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("could not parse transaction log location \"%s\"", locationstr))); locationpoint.xlogid = uxlogid; locationpoint.xrecoff = uxrecoff; /* * Construct a tuple descriptor for the result row. This must match this * function's pg_proc entry! */ resultTupleDesc = CreateTemplateTupleDesc(2, false); TupleDescInitEntry(resultTupleDesc, (AttrNumber) 1, "file_name", TEXTOID, -1, 0); TupleDescInitEntry(resultTupleDesc, (AttrNumber) 2, "file_offset", INT4OID, -1, 0); resultTupleDesc = BlessTupleDesc(resultTupleDesc); /* * xlogfilename */ XLByteToPrevSeg(locationpoint, xlogid, xlogseg); XLogFileName(xlogfilename, ThisTimeLineID, xlogid, xlogseg); values[0] = CStringGetTextDatum(xlogfilename); isnull[0] = false; /* * offset */ xrecoff = locationpoint.xrecoff - xlogseg * XLogSegSize; values[1] = UInt32GetDatum(xrecoff); isnull[1] = false; /* * Tuple jam: Having first prepared your Datums, then squash together */ resultHeapTuple = heap_form_tuple(resultTupleDesc, values, isnull); result = HeapTupleGetDatum(resultHeapTuple); PG_RETURN_DATUM(result); } /* * Compute an xlog file name given a WAL location, * such as is returned by pg_stop_backup() or pg_xlog_switch(). */ Datum pg_xlogfile_name(PG_FUNCTION_ARGS) { text *location = PG_GETARG_TEXT_P(0); char *locationstr; unsigned int uxlogid; unsigned int uxrecoff; uint32 xlogid; uint32 xlogseg; XLogRecPtr locationpoint; char xlogfilename[MAXFNAMELEN]; locationstr = text_to_cstring(location); if (sscanf(locationstr, "%X/%X", &uxlogid, &uxrecoff) != 2) ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("could not parse transaction log location \"%s\"", locationstr))); locationpoint.xlogid = uxlogid; locationpoint.xrecoff = uxrecoff; XLByteToPrevSeg(locationpoint, xlogid, xlogseg); XLogFileName(xlogfilename, ThisTimeLineID, xlogid, xlogseg); PG_RETURN_TEXT_P(cstring_to_text(xlogfilename)); } /* * 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. * * We also attempt to retrieve the corresponding backup history file. * If successful, set *minRecoveryLoc to constrain valid PITR stopping * points. * * Returns TRUE if a backup_label was found (and fills the checkpoint * location into *checkPointLoc); returns FALSE if not. */ static bool read_backup_label(XLogRecPtr *checkPointLoc, XLogRecPtr *minRecoveryLoc) { XLogRecPtr startpoint; XLogRecPtr stoppoint; char histfilename[MAXFNAMELEN]; char histfilepath[MAXPGPATH]; char startxlogfilename[MAXFNAMELEN]; char stopxlogfilename[MAXFNAMELEN]; TimeLineID tli; uint32 _logId; uint32 _logSeg; FILE *lfp; FILE *fp; char ch; /* Default is to not constrain recovery stop point */ minRecoveryLoc->xlogid = 0; minRecoveryLoc->xrecoff = 0; /* * 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", &startpoint.xlogid, &startpoint.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))); if (ferror(lfp) || FreeFile(lfp)) ereport(FATAL, (errcode_for_file_access(), errmsg("could not read file \"%s\": %m", BACKUP_LABEL_FILE))); /* * Try to retrieve the backup history file (no error if we can't) */ XLByteToSeg(startpoint, _logId, _logSeg); BackupHistoryFileName(histfilename, tli, _logId, _logSeg, startpoint.xrecoff % XLogSegSize); if (InArchiveRecovery) RestoreArchivedFile(histfilepath, histfilename, "RECOVERYHISTORY", 0); else BackupHistoryFilePath(histfilepath, tli, _logId, _logSeg, startpoint.xrecoff % XLogSegSize); fp = AllocateFile(histfilepath, "r"); if (fp) { /* * Parse history file to identify stop point. */ if (fscanf(fp, "START WAL LOCATION: %X/%X (file %24s)%c", &startpoint.xlogid, &startpoint.xrecoff, startxlogfilename, &ch) != 4 || ch != '\n') ereport(FATAL, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("invalid data in file \"%s\"", histfilename))); if (fscanf(fp, "STOP WAL LOCATION: %X/%X (file %24s)%c", &stoppoint.xlogid, &stoppoint.xrecoff, stopxlogfilename, &ch) != 4 || ch != '\n') ereport(FATAL, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("invalid data in file \"%s\"", histfilename))); *minRecoveryLoc = stoppoint; if (ferror(fp) || FreeFile(fp)) ereport(FATAL, (errcode_for_file_access(), errmsg("could not read file \"%s\": %m", histfilepath))); } 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 cancelled backup if it exists */ unlink(BACKUP_LABEL_OLD); if (rename(BACKUP_LABEL_FILE, BACKUP_LABEL_OLD) == 0) { ereport(LOG, (errmsg("online backup mode cancelled"), 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 cancelled"), errdetail("Could not rename \"%s\" to \"%s\": %m.", BACKUP_LABEL_FILE, BACKUP_LABEL_OLD))); } }