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postgresql/src/backend/access/transam/xlog.c

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/*-------------------------------------------------------------------------
*
* xlog.c
* PostgreSQL transaction log manager
*
*
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.356 2010/01/02 16:57:35 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <ctype.h>
#include <signal.h>
#include <time.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <unistd.h>
#include "access/clog.h"
#include "access/multixact.h"
#include "access/subtrans.h"
#include "access/transam.h"
#include "access/tuptoaster.h"
#include "access/twophase.h"
#include "access/xact.h"
#include "access/xlog_internal.h"
#include "access/xlogutils.h"
#include "catalog/catversion.h"
#include "catalog/pg_control.h"
#include "catalog/pg_database.h"
#include "catalog/pg_type.h"
#include "funcapi.h"
#include "libpq/pqsignal.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "postmaster/bgwriter.h"
#include "storage/bufmgr.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/guc.h"
#include "utils/ps_status.h"
#include "pg_trace.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;
bool XLogRequestRecoveryConnections = true;
int MaxStandbyDelay = 30;
bool fullPageWrites = true;
bool log_checkpoints = false;
int sync_method = DEFAULT_SYNC_METHOD;
#ifdef WAL_DEBUG
bool XLOG_DEBUG = false;
#endif
/*
* XLOGfileslop is the maximum number of preallocated future XLOG segments.
* When we are done with an old XLOG segment file, we will recycle it as a
* future XLOG segment as long as there aren't already XLOGfileslop future
* segments; else we'll delete it. This could be made a separate GUC
* variable, but at present I think it's sufficient to hardwire it as
* 2*CheckPointSegments+1. Under normal conditions, a checkpoint will free
* no more than 2*CheckPointSegments log segments, and we want to recycle all
* of them; the +1 allows boundary cases to happen without wasting a
* delete/create-segment cycle.
*/
#define XLOGfileslop (2*CheckPointSegments + 1)
/*
* GUC support
*/
const struct config_enum_entry sync_method_options[] = {
{"fsync", SYNC_METHOD_FSYNC, false},
#ifdef HAVE_FSYNC_WRITETHROUGH
{"fsync_writethrough", SYNC_METHOD_FSYNC_WRITETHROUGH, false},
#endif
#ifdef HAVE_FDATASYNC
{"fdatasync", SYNC_METHOD_FDATASYNC, false},
#endif
#ifdef OPEN_SYNC_FLAG
{"open_sync", SYNC_METHOD_OPEN, false},
#endif
#ifdef OPEN_DATASYNC_FLAG
{"open_datasync", SYNC_METHOD_OPEN_DSYNC, false},
#endif
{NULL, 0, false}
};
/*
* Statistics for current checkpoint are collected in this global struct.
* Because only the background writer or a stand-alone backend can perform
* checkpoints, this will be unused in normal backends.
*/
CheckpointStatsData CheckpointStats;
/*
* ThisTimeLineID will be same in all backends --- it identifies current
* WAL timeline for the database system.
*/
TimeLineID ThisTimeLineID = 0;
/*
* Are we doing recovery from XLOG?
*
* This is only ever true in the startup process; it should be read as meaning
* "this process is replaying WAL records", rather than "the system is in
* recovery mode". It should be examined primarily by functions that need
* to act differently when called from a WAL redo function (e.g., to skip WAL
* logging). To check whether the system is in recovery regardless of which
* process you're running in, use RecoveryInProgress() but only after shared
* memory startup and lock initialization.
*/
bool InRecovery = false;
/* Are we in Hot Standby mode? Only valid in startup process, see xlog.h */
HotStandbyState standbyState = STANDBY_DISABLED;
static XLogRecPtr LastRec;
/*
* Local copy of SharedRecoveryInProgress variable. True actually means "not
* known, need to check the shared state".
*/
static bool LocalRecoveryInProgress = true;
/*
* Local state for XLogInsertAllowed():
* 1: unconditionally allowed to insert XLOG
* 0: unconditionally not allowed to insert XLOG
* -1: must check RecoveryInProgress(); disallow until it is false
* Most processes start with -1 and transition to 1 after seeing that recovery
* is not in progress. But we can also force the value for special cases.
* The coding in XLogInsertAllowed() depends on the first two of these states
* being numerically the same as bool true and false.
*/
static int LocalXLogInsertAllowed = -1;
/* Are we recovering using offline XLOG archives? */
static bool InArchiveRecovery = false;
/* Was the last xlog file restored from archive, or local? */
static bool restoredFromArchive = false;
/* options taken from recovery.conf */
static char *recoveryRestoreCommand = NULL;
static char *recoveryEndCommand = NULL;
static bool recoveryTarget = false;
static bool recoveryTargetExact = false;
static bool recoveryTargetInclusive = true;
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 or restartpoint (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;
/*
* SharedRecoveryInProgress indicates if we're still in crash or archive
* recovery. Protected by info_lck.
*/
bool SharedRecoveryInProgress;
/*
* During recovery, we keep a copy of the latest checkpoint record here.
* Used by the background writer when it wants to create a restartpoint.
*
* Protected by info_lck.
*/
XLogRecPtr lastCheckPointRecPtr;
CheckPoint lastCheckPoint;
/* end+1 of the last record replayed (or being replayed) */
XLogRecPtr replayEndRecPtr;
/* timestamp of last record replayed (or being replayed) */
TimestampTz recoveryLastXTime;
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 XLogRecPtr minRecoveryPoint; /* local copy of
* ControlFile->minRecoveryPoint */
static bool updateMinRecoveryPoint = true;
static bool InRedo = false;
/*
* Flags set by interrupt handlers for later service in the redo loop.
*/
static volatile sig_atomic_t got_SIGHUP = false;
static volatile sig_atomic_t shutdown_requested = false;
/*
* Flag set when executing a restore command, to tell SIGTERM signal handler
* that it's safe to just proc_exit.
*/
static volatile sig_atomic_t in_restore_command = false;
static void XLogArchiveNotify(const char *xlog);
static void XLogArchiveNotifySeg(uint32 log, uint32 seg);
static bool XLogArchiveCheckDone(const char *xlog);
static bool XLogArchiveIsBusy(const char *xlog);
static void XLogArchiveCleanup(const char *xlog);
static void readRecoveryCommandFile(void);
static void exitArchiveRecovery(TimeLineID endTLI,
uint32 endLogId, uint32 endLogSeg);
static bool recoveryStopsHere(XLogRecord *record, bool *includeThis);
static void CheckRequiredParameterValues(CheckPoint checkPoint);
static void LocalSetXLogInsertAllowed(void);
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 ExecuteRecoveryEndCommand(void);
static void PreallocXlogFiles(XLogRecPtr endptr);
static void RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr);
static void ValidateXLOGDirectoryStructure(void);
static void CleanupBackupHistory(void);
static void UpdateMinRecoveryPoint(XLogRecPtr lsn, bool force);
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);
static int get_sync_bit(int method);
/*
* Insert an XLOG record having the specified RMID and info bytes,
* with the body of the record being the data chunk(s) described by
* the rdata chain (see xlog.h for notes about rdata).
*
* Returns XLOG pointer to end of record (beginning of next record).
* This can be used as LSN for data pages affected by the logged action.
* (LSN is the XLOG point up to which the XLOG must be flushed to disk
* before the data page can be written out. This implements the basic
* WAL rule "write the log before the data".)
*
* NB: this routine feels free to scribble on the XLogRecData structs,
* though not on the data they reference. This is OK since the XLogRecData
* structs are always just temporaries in the calling code.
*/
XLogRecPtr
XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata)
{
XLogCtlInsert *Insert = &XLogCtl->Insert;
XLogRecord *record;
XLogContRecord *contrecord;
XLogRecPtr RecPtr;
XLogRecPtr WriteRqst;
uint32 freespace;
int curridx;
XLogRecData *rdt;
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);
/* cross-check on whether we should be here or not */
if (!XLogInsertAllowed())
elog(ERROR, "cannot make new WAL entries during recovery");
/* info's high bits are reserved for use by me */
if (info & XLR_INFO_MASK)
elog(PANIC, "invalid xlog info mask %02X", info);
TRACE_POSTGRESQL_XLOG_INSERT(rmid, info);
/*
* In bootstrap mode, we don't actually log anything but XLOG resources;
* return a phony record pointer.
*/
if (IsBootstrapProcessingMode() && rmid != RM_XLOG_ID)
{
RecPtr.xlogid = 0;
RecPtr.xrecoff = SizeOfXLogLongPHD; /* start of 1st chkpt record */
return RecPtr;
}
/*
* Here we scan the rdata chain, 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;
TRACE_POSTGRESQL_XLOG_SWITCH();
LWLockAcquire(WALWriteLock, LW_EXCLUSIVE);
/*
* Flush through the end of the page containing XLOG_SWITCH, and
* perform end-of-segment actions (eg, notifying archiver).
*/
WriteRqst = XLogCtl->xlblocks[curridx];
FlushRqst.Write = WriteRqst;
FlushRqst.Flush = WriteRqst;
XLogWrite(FlushRqst, false, true);
/* Set up the next buffer as first page of next segment */
/* Note: AdvanceXLInsertBuffer cannot need to do I/O here */
(void) AdvanceXLInsertBuffer(true);
/* There should be no unwritten data */
curridx = Insert->curridx;
Assert(curridx == 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)
{
Page page;
page = BufferGetPage(rdata->buffer);
/*
* XXX We assume page LSN is first data on *every* page that can be passed
* to XLogInsert, whether it otherwise has the standard page layout or
* not.
*/
*lsn = PageGetLSN(page);
if (doPageWrites &&
XLByteLE(PageGetLSN(page), RedoRecPtr))
{
/*
* The page needs to be backed up, so set up *bkpb
*/
BufferGetTag(rdata->buffer, &bkpb->node, &bkpb->fork, &bkpb->block);
if (rdata->buffer_std)
{
/* Assume we can omit data between pd_lower and pd_upper */
uint16 lower = ((PageHeader) page)->pd_lower;
uint16 upper = ((PageHeader) page)->pd_upper;
if (lower >= SizeOfPageHeaderData &&
upper > lower &&
upper <= BLCKSZ)
{
bkpb->hole_offset = lower;
bkpb->hole_length = upper - lower;
}
else
{
/* No "hole" to compress out */
bkpb->hole_offset = 0;
bkpb->hole_length = 0;
}
}
else
{
/* Not a standard page header, don't try to eliminate "hole" */
bkpb->hole_offset = 0;
bkpb->hole_length = 0;
}
return true; /* buffer requires backup */
}
return false; /* buffer does not need to be backed up */
}
/*
* XLogArchiveNotify
*
* Create an archive notification file
*
* The name of the notification file is the message that will be picked up
* by the archiver, e.g. we write 0000000100000001000000C6.ready
* and the archiver then knows to archive XLOGDIR/0000000100000001000000C6,
* then when complete, rename it to 0000000100000001000000C6.done
*/
static void
XLogArchiveNotify(const char *xlog)
{
char archiveStatusPath[MAXPGPATH];
FILE *fd;
/* insert an otherwise empty file called <XLOG>.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 <XLOG>.done exists, then return true; else if <XLOG>.ready exists,
* then return false; else create <XLOG>.ready and return false.
*
* The reason we do things this way is so that if the original attempt to
* create <XLOG>.ready fails, we'll retry during subsequent checkpoints.
*/
static bool
XLogArchiveCheckDone(const char *xlog)
{
char archiveStatusPath[MAXPGPATH];
struct stat stat_buf;
/* Always deletable if archiving is off */
if (!XLogArchivingActive())
return true;
/* First check for .done --- this means archiver is done with it */
StatusFilePath(archiveStatusPath, xlog, ".done");
if (stat(archiveStatusPath, &stat_buf) == 0)
return true;
/* check for .ready --- this means archiver is still busy with it */
StatusFilePath(archiveStatusPath, xlog, ".ready");
if (stat(archiveStatusPath, &stat_buf) == 0)
return false;
/* Race condition --- maybe archiver just finished, so recheck */
StatusFilePath(archiveStatusPath, xlog, ".done");
if (stat(archiveStatusPath, &stat_buf) == 0)
return true;
/* Retry creation of the .ready file */
XLogArchiveNotify(xlog);
return false;
}
/*
* XLogArchiveIsBusy
*
* Check to see if an XLOG segment file is still unarchived.
* This is almost but not quite the inverse of XLogArchiveCheckDone: in
* the first place we aren't chartered to recreate the .ready file, and
* in the second place we should consider that if the file is already gone
* then it's not busy. (This check is needed to handle the race condition
* that a checkpoint already deleted the no-longer-needed file.)
*/
static bool
XLogArchiveIsBusy(const char *xlog)
{
char archiveStatusPath[MAXPGPATH];
struct stat stat_buf;
/* First check for .done --- this means archiver is done with it */
StatusFilePath(archiveStatusPath, xlog, ".done");
if (stat(archiveStatusPath, &stat_buf) == 0)
return false;
/* check for .ready --- this means archiver is still busy with it */
StatusFilePath(archiveStatusPath, xlog, ".ready");
if (stat(archiveStatusPath, &stat_buf) == 0)
return true;
/* Race condition --- maybe archiver just finished, so recheck */
StatusFilePath(archiveStatusPath, xlog, ".done");
if (stat(archiveStatusPath, &stat_buf) == 0)
return false;
/*
* Check to see if the WAL file has been removed by checkpoint, which
* implies it has already been archived, and explains why we can't see a
* status file for it.
*/
snprintf(archiveStatusPath, MAXPGPATH, XLOGDIR "/%s", xlog);
if (stat(archiveStatusPath, &stat_buf) != 0 &&
errno == ENOENT)
return false;
return true;
}
/*
* XLogArchiveCleanup
*
* Cleanup archive notification file(s) for a particular xlog segment
*/
static void
XLogArchiveCleanup(const char *xlog)
{
char archiveStatusPath[MAXPGPATH];
/* Remove the .done file */
StatusFilePath(archiveStatusPath, xlog, ".done");
unlink(archiveStatusPath);
/* should we complain about failure? */
/* Remove the .ready file if present --- normally it shouldn't be */
StatusFilePath(archiveStatusPath, xlog, ".ready");
unlink(archiveStatusPath);
/* should we complain about failure? */
}
/*
* Advance the Insert state to the next buffer page, writing out the next
* buffer if it still contains unwritten data.
*
* If new_segment is TRUE then we set up the next buffer page as the first
* page of the next xlog segment file, possibly but not usually the next
* consecutive file page.
*
* The global LogwrtRqst.Write pointer needs to be advanced to include the
* just-filled page. If we can do this for free (without an extra lock),
* we do so here. Otherwise the caller must do it. We return TRUE if the
* request update still needs to be done, FALSE if we did it internally.
*
* Must be called with WALInsertLock held.
*/
static bool
AdvanceXLInsertBuffer(bool new_segment)
{
XLogCtlInsert *Insert = &XLogCtl->Insert;
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.
*/
TRACE_POSTGRESQL_WAL_BUFFER_WRITE_DIRTY_START();
WriteRqst.Write = OldPageRqstPtr;
WriteRqst.Flush.xlogid = 0;
WriteRqst.Flush.xrecoff = 0;
XLogWrite(WriteRqst, false, false);
LWLockRelease(WALWriteLock);
Insert->LogwrtResult = LogwrtResult;
TRACE_POSTGRESQL_WAL_BUFFER_WRITE_DIRTY_DONE();
}
}
}
/*
* Now the next buffer slot is free and we can set it up to be the next
* output page.
*/
NewPageEndPtr = XLogCtl->xlblocks[Insert->curridx];
if (new_segment)
{
/* force it to a segment start point */
NewPageEndPtr.xrecoff += XLogSegSize - 1;
NewPageEndPtr.xrecoff -= NewPageEndPtr.xrecoff % XLogSegSize;
}
if (NewPageEndPtr.xrecoff >= XLogFileSize)
{
/* crossing a logid boundary */
NewPageEndPtr.xlogid += 1;
NewPageEndPtr.xrecoff = XLOG_BLCKSZ;
}
else
NewPageEndPtr.xrecoff += XLOG_BLCKSZ;
XLogCtl->xlblocks[nextidx] = NewPageEndPtr;
NewPage = (XLogPageHeader) (XLogCtl->pages + nextidx * (Size) XLOG_BLCKSZ);
Insert->curridx = nextidx;
Insert->currpage = NewPage;
Insert->currpos = ((char *) NewPage) +SizeOfXLogShortPHD;
/*
* Be sure to re-zero the buffer so that bytes beyond what we've written
* will look like zeroes and not valid XLOG records...
*/
MemSet((char *) NewPage, 0, XLOG_BLCKSZ);
/*
* Fill the new page's header
*/
NewPage ->xlp_magic = XLOG_PAGE_MAGIC;
/* NewPage->xlp_info = 0; */ /* done by memset */
NewPage ->xlp_tli = ThisTimeLineID;
NewPage ->xlp_pageaddr.xlogid = NewPageEndPtr.xlogid;
NewPage ->xlp_pageaddr.xrecoff = NewPageEndPtr.xrecoff - XLOG_BLCKSZ;
/*
* If 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 &&
sync_method != SYNC_METHOD_OPEN_DSYNC)
{
if (openLogFile >= 0 &&
!XLByteInPrevSeg(LogwrtResult.Write, openLogId, openLogSeg))
XLogFileClose();
if (openLogFile < 0)
{
XLByteToPrevSeg(LogwrtResult.Write, openLogId, openLogSeg);
openLogFile = XLogFileOpen(openLogId, openLogSeg);
openLogOff = 0;
}
issue_xlog_fsync();
}
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);
}
/*
* Advance minRecoveryPoint in control file.
*
* If we crash during recovery, we must reach this point again before the
* database is consistent.
*
* If 'force' is true, 'lsn' argument is ignored. Otherwise, minRecoveryPoint
* is only updated if it's not already greater than or equal to 'lsn'.
*/
static void
UpdateMinRecoveryPoint(XLogRecPtr lsn, bool force)
{
/* Quick check using our local copy of the variable */
if (!updateMinRecoveryPoint || (!force && XLByteLE(lsn, minRecoveryPoint)))
return;
LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
/* update local copy */
minRecoveryPoint = ControlFile->minRecoveryPoint;
/*
* An invalid minRecoveryPoint means that we need to recover all the WAL,
* i.e., we're doing crash recovery. We never modify the control file's
* value in that case, so we can short-circuit future checks here too.
*/
if (minRecoveryPoint.xlogid == 0 && minRecoveryPoint.xrecoff == 0)
updateMinRecoveryPoint = false;
else if (force || XLByteLT(minRecoveryPoint, lsn))
{
/* use volatile pointer to prevent code rearrangement */
volatile XLogCtlData *xlogctl = XLogCtl;
XLogRecPtr newMinRecoveryPoint;
/*
* To avoid having to update the control file too often, we update it
* all the way to the last record being replayed, even though 'lsn'
* would suffice for correctness. This also allows the 'force' case
* to not need a valid 'lsn' value.
*
* Another important reason for doing it this way is that the passed
* 'lsn' value could be bogus, i.e., past the end of available WAL,
* if the caller got it from a corrupted heap page. Accepting such
* a value as the min recovery point would prevent us from coming up
* at all. Instead, we just log a warning and continue with recovery.
* (See also the comments about corrupt LSNs in XLogFlush.)
*/
SpinLockAcquire(&xlogctl->info_lck);
newMinRecoveryPoint = xlogctl->replayEndRecPtr;
SpinLockRelease(&xlogctl->info_lck);
if (!force && XLByteLT(newMinRecoveryPoint, lsn))
elog(WARNING,
"xlog min recovery request %X/%X is past current point %X/%X",
lsn.xlogid, lsn.xrecoff,
newMinRecoveryPoint.xlogid, newMinRecoveryPoint.xrecoff);
/* update control file */
if (XLByteLT(ControlFile->minRecoveryPoint, newMinRecoveryPoint))
{
ControlFile->minRecoveryPoint = newMinRecoveryPoint;
UpdateControlFile();
minRecoveryPoint = newMinRecoveryPoint;
ereport(DEBUG2,
(errmsg("updated min recovery point to %X/%X",
minRecoveryPoint.xlogid, minRecoveryPoint.xrecoff)));
}
}
LWLockRelease(ControlFileLock);
}
/*
* Ensure that all XLOG data through the given position is flushed to disk.
*
* NOTE: this differs from XLogWrite mainly in that the WALWriteLock is not
* already held, and we try to avoid acquiring it if possible.
*/
void
XLogFlush(XLogRecPtr record)
{
XLogRecPtr WriteRqstPtr;
XLogwrtRqst WriteRqst;
/*
* During REDO, we are reading not writing WAL. Therefore, instead of
* trying to flush the WAL, we should update minRecoveryPoint instead.
* We test XLogInsertAllowed(), not InRecovery, because we need the
* bgwriter to act this way too, and because when the bgwriter tries
* to write the end-of-recovery checkpoint, it should indeed flush.
*/
if (!XLogInsertAllowed())
{
UpdateMinRecoveryPoint(record, false);
return;
}
/* Quick exit if already known flushed */
if (XLByteLE(record, LogwrtResult.Flush))
return;
#ifdef WAL_DEBUG
if (XLOG_DEBUG)
elog(LOG, "xlog flush request %X/%X; write %X/%X; flush %X/%X",
record.xlogid, record.xrecoff,
LogwrtResult.Write.xlogid, LogwrtResult.Write.xrecoff,
LogwrtResult.Flush.xlogid, LogwrtResult.Flush.xrecoff);
#endif
START_CRIT_SECTION();
/*
* Since fsync is usually a horribly expensive operation, we try to
* piggyback as much data as we can on each fsync: if we see any more data
* entered into the xlog buffer, we'll write and fsync that too, so that
* the final value of LogwrtResult.Flush is as large as possible. This
* gives us some chance of avoiding another fsync immediately after.
*/
/* initialize to given target; may increase below */
WriteRqstPtr = record;
/* 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 actually
* happened in the field several times with 7.1 releases.) As of 8.4,
* bad LSNs encountered during recovery are UpdateMinRecoveryPoint's
* problem; the only time we can reach here during recovery is while
* flushing the end-of-recovery checkpoint record, and we don't expect
* that to have a bad LSN.
*
* Note that for calls from xact.c, the ERROR will
* be promoted to PANIC since xact.c calls this routine inside a critical
* section. However, calls from bufmgr.c are not within critical sections
* and so we will not force a restart for a bad LSN on a data page.
*/
if (XLByteLT(LogwrtResult.Flush, record))
elog(ERROR,
"xlog flush request %X/%X is not satisfied --- flushed only to %X/%X",
record.xlogid, record.xrecoff,
LogwrtResult.Flush.xlogid, LogwrtResult.Flush.xrecoff);
}
/*
* Flush xlog, but without specifying exactly where to flush to.
*
* We normally flush only completed blocks; but if there is nothing to do on
* that basis, we check for unflushed async commits in the current incomplete
* block, and flush through the latest one of those. Thus, if async commits
* are not being used, we will flush complete blocks only. We can guarantee
* that async commits reach disk after at most three cycles; normally only
* one or two. (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;
/* XLOG doesn't need flushing during recovery */
if (RecoveryInProgress())
return;
/* 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;
/* There's no asynchronously committed transactions during recovery */
if (RecoveryInProgress())
return;
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)
{
/*
* During recovery, we don't flush WAL but update minRecoveryPoint
* instead. So "needs flush" is taken to mean whether minRecoveryPoint
* would need to be updated.
*/
if (RecoveryInProgress())
{
/* Quick exit if already known updated */
if (XLByteLE(record, minRecoveryPoint) || !updateMinRecoveryPoint)
return false;
/*
* Update local copy of minRecoveryPoint. But if the lock is busy,
* just return a conservative guess.
*/
if (!LWLockConditionalAcquire(ControlFileLock, LW_SHARED))
return true;
minRecoveryPoint = ControlFile->minRecoveryPoint;
LWLockRelease(ControlFileLock);
/*
* An invalid minRecoveryPoint means that we need to recover all the WAL,
* i.e., we're doing crash recovery. We never modify the control file's
* value in that case, so we can short-circuit future checks here too.
*/
if (minRecoveryPoint.xlogid == 0 && minRecoveryPoint.xrecoff == 0)
updateMinRecoveryPoint = false;
/* check again */
if (XLByteLE(record, minRecoveryPoint) || !updateMinRecoveryPoint)
return false;
else
return true;
}
/* Quick exit if already known flushed */
if (XLByteLE(record, LogwrtResult.Flush))
return false;
/* read LogwrtResult and update local state */
{
/* use volatile pointer to prevent code rearrangement */
volatile XLogCtlData *xlogctl = XLogCtl;
SpinLockAcquire(&xlogctl->info_lck);
LogwrtResult = xlogctl->LogwrtResult;
SpinLockRelease(&xlogctl->info_lck);
}
/* check again */
if (XLByteLE(record, LogwrtResult.Flush))
return false;
return true;
}
/*
* Create a new XLOG file segment, or open a pre-existing one.
*
* log, seg: identify segment to be created/opened.
*
* *use_existent: if TRUE, OK to use a pre-existing file (else, any
* pre-existing file will be deleted). On return, TRUE if a pre-existing
* file was used.
*
* use_lock: if TRUE, acquire ControlFileLock while moving file into
* place. This should be TRUE except during bootstrap log creation. The
* caller must *not* hold the lock at call.
*
* Returns FD of opened file.
*
* Note: errors here are ERROR not PANIC because we might or might not be
* inside a critical section (eg, during checkpoint there is no reason to
* take down the system on failure). They will promote to PANIC if we are
* in a critical section.
*/
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 | get_sync_bit(sync_method),
S_IRUSR | S_IWUSR);
if (fd < 0)
{
if (errno != ENOENT)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open file \"%s\" (log file %u, segment %u): %m",
path, log, seg)));
}
else
return fd;
}
/*
* Initialize an empty (all zeroes) segment. NOTE: it is possible that
* another process is doing the same thing. If so, we will end up
* pre-creating an extra log segment. That seems OK, and better than
* holding the lock throughout this lengthy process.
*/
elog(DEBUG2, "creating and filling new WAL file");
snprintf(tmppath, MAXPGPATH, XLOGDIR "/xlogtemp.%d", (int) getpid());
unlink(tmppath);
/* do not use get_sync_bit() here --- want to fsync only at end of fill */
fd = BasicOpenFile(tmppath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
S_IRUSR | S_IWUSR);
if (fd < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not create file \"%s\": %m", tmppath)));
/*
* Zero-fill the file. We have to do this the hard way to ensure that all
* the file space has really been allocated --- on platforms that allow
* "holes" in files, just seeking to the end doesn't allocate intermediate
* space. This way, we know that we have all the space and (after the
* fsync below) that all the indirect blocks are down on disk. Therefore,
* fdatasync(2) or O_DSYNC will be sufficient to sync future writes to the
* log file.
*
* Note: palloc zbuffer, instead of just using a local char array, to
* ensure it is reasonably well-aligned; this may save a few cycles
* transferring data to the kernel.
*/
zbuffer = (char *) palloc0(XLOG_BLCKSZ);
for (nbytes = 0; nbytes < XLogSegSize; nbytes += XLOG_BLCKSZ)
{
errno = 0;
if ((int) write(fd, zbuffer, XLOG_BLCKSZ) != (int) XLOG_BLCKSZ)
{
int save_errno = errno;
/*
* If we fail to make the file, delete it to release disk space
*/
unlink(tmppath);
/* if write didn't set errno, assume problem is no disk space */
errno = save_errno ? save_errno : ENOSPC;
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not write to file \"%s\": %m", tmppath)));
}
}
pfree(zbuffer);
if (pg_fsync(fd) != 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not fsync file \"%s\": %m", tmppath)));
if (close(fd))
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not close file \"%s\": %m", tmppath)));
/*
* Now move the segment into place with its final name.
*
* If caller didn't want to use a pre-existing file, get rid of any
* pre-existing file. Otherwise, cope with possibility that someone else
* has created the file while we were filling ours: if so, use ours to
* pre-create a future log segment.
*/
installed_log = log;
installed_seg = seg;
max_advance = XLOGfileslop;
if (!InstallXLogFileSegment(&installed_log, &installed_seg, tmppath,
*use_existent, &max_advance,
use_lock))
{
/*
* No need for any more future segments, or InstallXLogFileSegment()
* failed to rename the file into place. If the rename failed, opening
* the file below will fail.
*/
unlink(tmppath);
}
/* Set flag to tell caller there was no existent file */
*use_existent = false;
/* Now open original target segment (might not be file I just made) */
fd = BasicOpenFile(path, O_RDWR | PG_BINARY | get_sync_bit(sync_method),
S_IRUSR | S_IWUSR);
if (fd < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open file \"%s\" (log file %u, segment %u): %m",
path, log, seg)));
elog(DEBUG2, "done creating and filling new WAL file");
return fd;
}
/*
* Create a new XLOG file segment by copying a pre-existing one.
*
* log, seg: identify segment to be created.
*
* srcTLI, srclog, srcseg: identify segment to be copied (could be from
* a different timeline)
*
* Currently this is only used during recovery, and so there are no locking
* considerations. But we should be just as tense as XLogFileInit to avoid
* emplacing a bogus file.
*/
static void
XLogFileCopy(uint32 log, uint32 seg,
TimeLineID srcTLI, uint32 srclog, uint32 srcseg)
{
char path[MAXPGPATH];
char tmppath[MAXPGPATH];
char buffer[XLOG_BLCKSZ];
int srcfd;
int fd;
int nbytes;
/*
* Open the source file
*/
XLogFilePath(path, srcTLI, srclog, srcseg);
srcfd = BasicOpenFile(path, O_RDONLY | PG_BINARY, 0);
if (srcfd < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open file \"%s\": %m", path)));
/*
* Copy into a temp file name.
*/
snprintf(tmppath, MAXPGPATH, XLOGDIR "/xlogtemp.%d", (int) getpid());
unlink(tmppath);
/* do not use get_sync_bit() here --- want to fsync only at end of fill */
fd = BasicOpenFile(tmppath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
S_IRUSR | S_IWUSR);
if (fd < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not create file \"%s\": %m", tmppath)));
/*
* Do the data copying.
*/
for (nbytes = 0; nbytes < XLogSegSize; nbytes += sizeof(buffer))
{
errno = 0;
if ((int) read(srcfd, buffer, sizeof(buffer)) != (int) sizeof(buffer))
{
if (errno != 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read file \"%s\": %m", path)));
else
ereport(ERROR,
(errmsg("not enough data in file \"%s\"", path)));
}
errno = 0;
if ((int) write(fd, buffer, sizeof(buffer)) != (int) sizeof(buffer))
{
int save_errno = errno;
/*
* If we fail to make the file, delete it to release disk space
*/
unlink(tmppath);
/* if write didn't set errno, assume problem is no disk space */
errno = save_errno ? save_errno : ENOSPC;
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not write to file \"%s\": %m", tmppath)));
}
}
if (pg_fsync(fd) != 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not fsync file \"%s\": %m", tmppath)));
if (close(fd))
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not close file \"%s\": %m", tmppath)));
close(srcfd);
/*
* Now move the segment into place with its final name.
*/
if (!InstallXLogFileSegment(&log, &seg, tmppath, false, NULL, false))
elog(ERROR, "InstallXLogFileSegment should not have failed");
}
/*
* Install a new XLOG segment file as a current or future log segment.
*
* This is used both to install a newly-created segment (which has a temp
* filename while it's being created) and to recycle an old segment.
*
* *log, *seg: identify segment to install as (or first possible target).
* When find_free is TRUE, these are modified on return to indicate the
* actual installation location or last segment searched.
*
* tmppath: initial name of file to install. It will be renamed into place.
*
* find_free: if TRUE, install the new segment at the first empty log/seg
* number at or after the passed numbers. If FALSE, install the new segment
* exactly where specified, deleting any existing segment file there.
*
* *max_advance: maximum number of log/seg slots to advance past the starting
* point. Fail if no free slot is found in this range. On return, reduced
* by the number of slots skipped over. (Irrelevant, and may be NULL,
* when find_free is FALSE.)
*
* use_lock: if TRUE, acquire ControlFileLock while moving file into
* place. This should be TRUE except during bootstrap log creation. The
* caller must *not* hold the lock at call.
*
* Returns TRUE if the file was installed successfully. FALSE indicates that
* max_advance limit was exceeded, or an error occurred while renaming the
* file into place.
*/
static bool
InstallXLogFileSegment(uint32 *log, uint32 *seg, char *tmppath,
bool find_free, int *max_advance,
bool use_lock)
{
char path[MAXPGPATH];
struct stat stat_buf;
XLogFilePath(path, ThisTimeLineID, *log, *seg);
/*
* We want to be sure that only one process does this at a time.
*/
if (use_lock)
LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
if (!find_free)
{
/* Force installation: get rid of any pre-existing segment file */
unlink(path);
}
else
{
/* Find a free slot to put it in */
while (stat(path, &stat_buf) == 0)
{
if (*max_advance <= 0)
{
/* Failed to find a free slot within specified range */
if (use_lock)
LWLockRelease(ControlFileLock);
return false;
}
NextLogSeg(*log, *seg);
(*max_advance)--;
XLogFilePath(path, ThisTimeLineID, *log, *seg);
}
}
/*
* Prefer link() to rename() here just to be really sure that we don't
* overwrite an existing logfile. However, there shouldn't be one, so
* rename() is an acceptable substitute except for the truly paranoid.
*/
#if HAVE_WORKING_LINK
if (link(tmppath, path) < 0)
{
if (use_lock)
LWLockRelease(ControlFileLock);
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not link file \"%s\" to \"%s\" (initialization of log file %u, segment %u): %m",
tmppath, path, *log, *seg)));
return false;
}
unlink(tmppath);
#else
if (rename(tmppath, path) < 0)
{
if (use_lock)
LWLockRelease(ControlFileLock);
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not rename file \"%s\" to \"%s\" (initialization of log file %u, segment %u): %m",
tmppath, path, *log, *seg)));
return false;
}
#endif
if (use_lock)
LWLockRelease(ControlFileLock);
return true;
}
/*
* Open a pre-existing logfile segment for writing.
*/
static int
XLogFileOpen(uint32 log, uint32 seg)
{
char path[MAXPGPATH];
int fd;
XLogFilePath(path, ThisTimeLineID, log, seg);
fd = BasicOpenFile(path, O_RDWR | PG_BINARY | get_sync_bit(sync_method),
S_IRUSR | S_IWUSR);
if (fd < 0)
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not open file \"%s\" (log file %u, segment %u): %m",
path, log, seg)));
return fd;
}
/*
* Open a logfile segment for reading (during recovery).
*/
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);
/*
* WAL segment files will not be re-read in normal operation, so we advise
* the OS to release any cached pages. But do not do so if WAL archiving
* is active, because archiver process could use the cache to read the WAL
* segment. Also, don't bother with it if we are using O_DIRECT, since
* the kernel is presumably not caching in that case.
*/
#if defined(USE_POSIX_FADVISE) && defined(POSIX_FADV_DONTNEED)
if (!XLogArchivingActive() &&
(get_sync_bit(sync_method) & PG_O_DIRECT) == 0)
(void) posix_fadvise(openLogFile, 0, 0, POSIX_FADV_DONTNEED);
#endif
if (close(openLogFile))
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not close log file %u, segment %u: %m",
openLogId, openLogSeg)));
openLogFile = -1;
}
/*
* Attempt to retrieve the specified file from off-line archival storage.
* If successful, fill "path" with its complete path (note that this will be
* a temp file name that doesn't follow the normal naming convention), and
* return TRUE.
*
* If not successful, fill "path" with the name of the normal on-line file
* (which may or may not actually exist, but we'll try to use it), and return
* FALSE.
*
* For fixed-size files, the caller may pass the expected size as an
* additional crosscheck on successful recovery. If the file size is not
* known, set expectedSize = 0.
*/
static bool
RestoreArchivedFile(char *path, const char *xlogfname,
const char *recovername, off_t expectedSize)
{
char xlogpath[MAXPGPATH];
char xlogRestoreCmd[MAXPGPATH];
char lastRestartPointFname[MAXPGPATH];
char *dp;
char *endp;
const char *sp;
int rc;
bool signaled;
struct stat stat_buf;
uint32 restartLog;
uint32 restartSeg;
/*
* 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)));
/*
* Set in_restore_command to tell the signal handler that we should exit
* right away on SIGTERM. We know that we're at a safe point to do that.
* Check if we had already received the signal, so that we don't miss a
* shutdown request received just before this.
*/
in_restore_command = true;
if (shutdown_requested)
proc_exit(1);
/*
* Copy xlog from archival storage to XLOGDIR
*/
rc = system(xlogRestoreCmd);
in_restore_command = false;
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.
*
* On SIGTERM, assume we have received a fast shutdown request, and exit
* cleanly. It's pure chance whether we receive the SIGTERM first, or the
* child process. If we receive it first, the signal handler will call
* proc_exit, otherwise we do it here. If we or the child process received
* SIGTERM for any other reason than a fast shutdown request, postmaster
* will perform an immediate shutdown when it sees us exiting
* unexpectedly.
*
* Per the Single Unix Spec, shells report exit status > 128 when a called
* command died on a signal. Also, 126 and 127 are used to report
* problems such as an unfindable command; treat those as fatal errors
* too.
*/
if (WIFSIGNALED(rc) && WTERMSIG(rc) == SIGTERM)
proc_exit(1);
signaled = WIFSIGNALED(rc) || WEXITSTATUS(rc) > 125;
ereport(signaled ? FATAL : DEBUG2,
(errmsg("could not restore file \"%s\" from archive: return code %d",
xlogfname, rc)));
/*
* if an archived file is not available, there might still be a version of
* this file in XLOGDIR, so return that as the filename to open.
*
* In many recovery scenarios we expect this to fail also, but if so that
* just means we've reached the end of WAL.
*/
snprintf(path, MAXPGPATH, XLOGDIR "/%s", xlogfname);
return false;
}
/*
* Attempt to execute the recovery_end_command.
*/
static void
ExecuteRecoveryEndCommand(void)
{
char xlogRecoveryEndCmd[MAXPGPATH];
char lastRestartPointFname[MAXPGPATH];
char *dp;
char *endp;
const char *sp;
int rc;
bool signaled;
uint32 restartLog;
uint32 restartSeg;
Assert(recoveryEndCommand);
/*
* 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);
}
else
XLogFileName(lastRestartPointFname, 0, 0, 0);
/*
* construct the command to be executed
*/
dp = xlogRecoveryEndCmd;
endp = xlogRecoveryEndCmd + MAXPGPATH - 1;
*endp = '\0';
for (sp = recoveryEndCommand; *sp; sp++)
{
if (*sp == '%')
{
switch (sp[1])
{
case 'r':
/* %r: filename of last restartpoint */
sp++;
StrNCpy(dp, lastRestartPointFname, endp - dp);
dp += strlen(dp);
break;
case '%':
/* convert %% to a single % */
sp++;
if (dp < endp)
*dp++ = *sp;
break;
default:
/* otherwise treat the % as not special */
if (dp < endp)
*dp++ = *sp;
break;
}
}
else
{
if (dp < endp)
*dp++ = *sp;
}
}
*dp = '\0';
ereport(DEBUG3,
(errmsg_internal("executing recovery end command \"%s\"",
xlogRecoveryEndCmd)));
/*
* execute the constructed command
*/
rc = system(xlogRecoveryEndCmd);
if (rc != 0)
{
/*
* If the failure was due to any sort of signal, it's best to punt and
* abort recovery. See also detailed comments on signals in
* RestoreArchivedFile().
*/
signaled = WIFSIGNALED(rc) || WEXITSTATUS(rc) > 125;
ereport(signaled ? FATAL : WARNING,
(errmsg("recovery_end_command \"%s\": return code %d",
xlogRecoveryEndCmd, rc)));
}
}
/*
* Preallocate log files beyond the specified log endpoint.
*
* XXX this is currently extremely conservative, since it forces only one
* future log segment to exist, and even that only if we are 75% done with
* the current one. This is only appropriate for very low-WAL-volume systems.
* High-volume systems will be OK once they've built up a sufficient set of
* recycled log segments, but the startup transient is likely to include
* a lot of segment creations by foreground processes, which is not so good.
*/
static void
PreallocXlogFiles(XLogRecPtr endptr)
{
uint32 _logId;
uint32 _logSeg;
int lf;
bool use_existent;
XLByteToPrevSeg(endptr, _logId, _logSeg);
if ((endptr.xrecoff - 1) % XLogSegSize >=
(uint32) (0.75 * XLogSegSize))
{
NextLogSeg(_logId, _logSeg);
use_existent = true;
lf = XLogFileInit(_logId, _logSeg, &use_existent, true);
close(lf);
if (!use_existent)
CheckpointStats.ckpt_segs_added++;
}
}
/*
* Recycle or remove all log files older or equal to passed log/seg#
*
* endptr is current (or recent) end of xlog; this is used to determine
* whether we want to recycle rather than delete no-longer-wanted log files.
*/
static void
RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr)
{
uint32 endlogId;
uint32 endlogSeg;
int max_advance;
DIR *xldir;
struct dirent *xlde;
char lastoff[MAXFNAMELEN];
char path[MAXPGPATH];
#ifdef WIN32
char newpath[MAXPGPATH];
#endif
struct stat statbuf;
/*
* Initialize info about where to try to recycle to. We allow recycling
* segments up to XLOGfileslop segments beyond the current XLOG location.
*/
XLByteToPrevSeg(endptr, endlogId, endlogSeg);
max_advance = XLOGfileslop;
xldir = AllocateDir(XLOGDIR);
if (xldir == NULL)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open transaction log directory \"%s\": %m",
XLOGDIR)));
XLogFileName(lastoff, ThisTimeLineID, log, seg);
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))
{
snprintf(path, MAXPGPATH, XLOGDIR "/%s", xlde->d_name);
/*
* Before deleting the file, see if it can be recycled as a
* future log segment. Only recycle normal files, pg_standby
* for example can create symbolic links pointing to a
* separate archive directory.
*/
if (lstat(path, &statbuf) == 0 && S_ISREG(statbuf.st_mode) &&
InstallXLogFileSegment(&endlogId, &endlogSeg, path,
true, &max_advance, true))
{
ereport(DEBUG2,
(errmsg("recycled transaction log file \"%s\"",
xlde->d_name)));
CheckpointStats.ckpt_segs_recycled++;
/* Needn't recheck that slot on future iterations */
if (max_advance > 0)
{
NextLogSeg(endlogId, endlogSeg);
max_advance--;
}
}
else
{
/* No need for any more future segments... */
int rc;
ereport(DEBUG2,
(errmsg("removing transaction log file \"%s\"",
xlde->d_name)));
#ifdef WIN32
/*
* On Windows, if another process (e.g another backend)
* holds the file open in FILE_SHARE_DELETE mode, unlink
* will succeed, but the file will still show up in
* directory listing until the last handle is closed.
* To avoid confusing the lingering deleted file for a
* live WAL file that needs to be archived, rename it
* before deleting it.
*
* If another process holds the file open without
* FILE_SHARE_DELETE flag, rename will fail. We'll try
* again at the next checkpoint.
*/
snprintf(newpath, MAXPGPATH, "%s.deleted", path);
if (rename(path, newpath) != 0)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not rename old transaction log file \"%s\": %m",
path)));
continue;
}
rc = unlink(newpath);
#else
rc = unlink(path);
#endif
if (rc != 0)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not remove old transaction log file \"%s\": %m",
path)));
continue;
}
CheckpointStats.ckpt_segs_removed++;
}
XLogArchiveCleanup(xlde->d_name);
}
}
}
FreeDir(xldir);
}
/*
* Verify whether pg_xlog and pg_xlog/archive_status exist.
* If the latter does not exist, recreate it.
*
* It is not the goal of this function to verify the contents of these
* directories, but to help in cases where someone has performed a cluster
* copy for PITR purposes but omitted pg_xlog from the copy.
*
* We could also recreate pg_xlog if it doesn't exist, but a deliberate
* policy decision was made not to. It is fairly common for pg_xlog to be
* a symlink, and if that was the DBA's intent then automatically making a
* plain directory would result in degraded performance with no notice.
*/
static void
ValidateXLOGDirectoryStructure(void)
{
char path[MAXPGPATH];
struct stat stat_buf;
/* Check for pg_xlog; if it doesn't exist, error out */
if (stat(XLOGDIR, &stat_buf) != 0 ||
!S_ISDIR(stat_buf.st_mode))
ereport(FATAL,
(errmsg("required WAL directory \"%s\" does not exist",
XLOGDIR)));
/* Check for archive_status */
snprintf(path, MAXPGPATH, XLOGDIR "/archive_status");
if (stat(path, &stat_buf) == 0)
{
/* Check for weird cases where it exists but isn't a directory */
if (!S_ISDIR(stat_buf.st_mode))
ereport(FATAL,
(errmsg("required WAL directory \"%s\" does not exist",
path)));
}
else
{
ereport(LOG,
(errmsg("creating missing WAL directory \"%s\"", path)));
if (mkdir(path, 0700) < 0)
ereport(FATAL,
(errmsg("could not create missing directory \"%s\": %m",
path)));
}
}
/*
* Remove previous backup history files. This also retries creation of
* .ready files for any backup history files for which XLogArchiveNotify
* failed earlier.
*/
static void
CleanupBackupHistory(void)
{
DIR *xldir;
struct dirent *xlde;
char path[MAXPGPATH];
xldir = AllocateDir(XLOGDIR);
if (xldir == NULL)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open transaction log directory \"%s\": %m",
XLOGDIR)));
while ((xlde = ReadDir(xldir, XLOGDIR)) != NULL)
{
if (strlen(xlde->d_name) > 24 &&
strspn(xlde->d_name, "0123456789ABCDEF") == 24 &&
strcmp(xlde->d_name + strlen(xlde->d_name) - strlen(".backup"),
".backup") == 0)
{
if (XLogArchiveCheckDone(xlde->d_name))
{
ereport(DEBUG2,
(errmsg("removing transaction log backup history file \"%s\"",
xlde->d_name)));
snprintf(path, MAXPGPATH, XLOGDIR "/%s", xlde->d_name);
unlink(path);
XLogArchiveCleanup(xlde->d_name);
}
}
}
FreeDir(xldir);
}
/*
* Restore the backup blocks present in an XLOG record, if any.
*
* We assume all of the record has been read into memory at *record.
*
* Note: when a backup block is available in XLOG, we restore it
* unconditionally, even if the page in the database appears newer.
* This is to protect ourselves against database pages that were partially
* or incorrectly written during a crash. We assume that the XLOG data
* must be good because it has passed a CRC check, while the database
* page might not be. This will force us to replay all subsequent
* modifications of the page that appear in XLOG, rather than possibly
* ignoring them as already applied, but that's not a huge drawback.
*
* If 'cleanup' is true, a cleanup lock is used when restoring blocks.
* Otherwise, a normal exclusive lock is used. During crash recovery, that's
* just pro forma because there can't be any regular backends in the system,
* but in hot standby mode the distinction is important. The 'cleanup'
* argument applies to all backup blocks in the WAL record, that suffices for
* now.
*/
void
RestoreBkpBlocks(XLogRecPtr lsn, XLogRecord *record, bool cleanup)
{
Buffer buffer;
Page page;
BkpBlock bkpb;
char *blk;
int i;
if (!(record->xl_info & XLR_BKP_BLOCK_MASK))
return;
blk = (char *) XLogRecGetData(record) + record->xl_len;
for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++)
{
if (!(record->xl_info & XLR_SET_BKP_BLOCK(i)))
continue;
memcpy(&bkpb, blk, sizeof(BkpBlock));
blk += sizeof(BkpBlock);
buffer = XLogReadBufferExtended(bkpb.node, bkpb.fork, bkpb.block,
RBM_ZERO);
Assert(BufferIsValid(buffer));
if (cleanup)
LockBufferForCleanup(buffer);
else
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
page = (Page) BufferGetPage(buffer);
if (bkpb.hole_length == 0)
{
memcpy((char *) page, blk, BLCKSZ);
}
else
{
/* 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:;
if (readFile >= 0)
{
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 get_sync_bit() here --- want to fsync only at end of fill */
fd = BasicOpenFile(tmppath, O_RDWR | O_CREAT | O_EXCL,
S_IRUSR | S_IWUSR);
if (fd < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not create file \"%s\": %m", tmppath)));
/*
* If a history file exists for the parent, copy it verbatim
*/
if (InArchiveRecovery)
{
TLHistoryFileName(histfname, parentTLI);
RestoreArchivedFile(path, histfname, "RECOVERYHISTORY", 0);
}
else
TLHistoryFilePath(path, parentTLI);
srcfd = BasicOpenFile(path, O_RDONLY, 0);
if (srcfd < 0)
{
if (errno != ENOENT)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open file \"%s\": %m", path)));
/* Not there, so assume parent has no parents */
}
else
{
for (;;)
{
errno = 0;
nbytes = (int) read(srcfd, buffer, sizeof(buffer));
if (nbytes < 0 || errno != 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read file \"%s\": %m", path)));
if (nbytes == 0)
break;
errno = 0;
if ((int) write(fd, buffer, nbytes) != nbytes)
{
int save_errno = errno;
/*
* If we fail to make the file, delete it to release disk
* space
*/
unlink(tmppath);
/*
* if write didn't set errno, assume problem is no disk space
*/
errno = save_errno ? save_errno : ENOSPC;
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not write to file \"%s\": %m", tmppath)));
}
}
close(srcfd);
}
/*
* Append one line with the details of this timeline split.
*
* If we did have a parent file, insert an extra newline just in case the
* parent file failed to end with one.
*/
XLogFileName(xlogfname, endTLI, endLogId, endLogSeg);
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 */
/*
* Initialize version and compatibility-check fields
*/
ControlFile->pg_control_version = PG_CONTROL_VERSION;
ControlFile->catalog_version_no = CATALOG_VERSION_NO;
ControlFile->maxAlign = MAXIMUM_ALIGNOF;
ControlFile->floatFormat = FLOATFORMAT_VALUE;
ControlFile->blcksz = BLCKSZ;
ControlFile->relseg_size = RELSEG_SIZE;
ControlFile->xlog_blcksz = XLOG_BLCKSZ;
ControlFile->xlog_seg_size = XLOG_SEG_SIZE;
ControlFile->nameDataLen = NAMEDATALEN;
ControlFile->indexMaxKeys = INDEX_MAX_KEYS;
ControlFile->toast_max_chunk_size = TOAST_MAX_CHUNK_SIZE;
#ifdef HAVE_INT64_TIMESTAMP
ControlFile->enableIntTimes = true;
#else
ControlFile->enableIntTimes = false;
#endif
ControlFile->float4ByVal = FLOAT4PASSBYVAL;
ControlFile->float8ByVal = FLOAT8PASSBYVAL;
/* Contents are protected with a CRC */
INIT_CRC32(ControlFile->crc);
COMP_CRC32(ControlFile->crc,
(char *) ControlFile,
offsetof(ControlFileData, crc));
FIN_CRC32(ControlFile->crc);
/*
* We write out PG_CONTROL_SIZE bytes into pg_control, zero-padding the
* excess over sizeof(ControlFileData). This reduces the odds of
* premature-EOF errors when reading pg_control. We'll still fail when we
* check the contents of the file, but hopefully with a more specific
* error than "couldn't read pg_control".
*/
if (sizeof(ControlFileData) > PG_CONTROL_SIZE)
elog(PANIC, "sizeof(ControlFileData) is larger than PG_CONTROL_SIZE; fix either one");
memset(buffer, 0, PG_CONTROL_SIZE);
memcpy(buffer, ControlFile, sizeof(ControlFileData));
fd = BasicOpenFile(XLOG_CONTROL_FILE,
O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
S_IRUSR | S_IWUSR);
if (fd < 0)
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not create control file \"%s\": %m",
XLOG_CONTROL_FILE)));
errno = 0;
if (write(fd, buffer, PG_CONTROL_SIZE) != PG_CONTROL_SIZE)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not write to control file: %m")));
}
if (pg_fsync(fd) != 0)
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not fsync control file: %m")));
if (close(fd))
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not close control file: %m")));
}
static void
ReadControlFile(void)
{
pg_crc32 crc;
int fd;
/*
* Read data...
*/
fd = BasicOpenFile(XLOG_CONTROL_FILE,
O_RDWR | PG_BINARY,
S_IRUSR | S_IWUSR);
if (fd < 0)
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not open control file \"%s\": %m",
XLOG_CONTROL_FILE)));
if (read(fd, ControlFile, sizeof(ControlFileData)) != sizeof(ControlFileData))
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not read from control file: %m")));
close(fd);
/*
* Check for expected pg_control format version. If this is wrong, the
* CRC check will likely fail because we'll be checking the wrong number
* of bytes. Complaining about wrong version will probably be more
* enlightening than complaining about wrong CRC.
*/
if (ControlFile->pg_control_version != PG_CONTROL_VERSION && ControlFile->pg_control_version % 65536 == 0 && ControlFile->pg_control_version / 65536 != 0)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized with PG_CONTROL_VERSION %d (0x%08x),"
" but the server was compiled with PG_CONTROL_VERSION %d (0x%08x).",
ControlFile->pg_control_version, ControlFile->pg_control_version,
PG_CONTROL_VERSION, PG_CONTROL_VERSION),
errhint("This could be a problem of mismatched byte ordering. It looks like you need to initdb.")));
if (ControlFile->pg_control_version != PG_CONTROL_VERSION)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized with PG_CONTROL_VERSION %d,"
" but the server was compiled with PG_CONTROL_VERSION %d.",
ControlFile->pg_control_version, PG_CONTROL_VERSION),
errhint("It looks like you need to initdb.")));
/* Now check the CRC. */
INIT_CRC32(crc);
COMP_CRC32(crc,
(char *) ControlFile,
offsetof(ControlFileData, crc));
FIN_CRC32(crc);
if (!EQ_CRC32(crc, ControlFile->crc))
ereport(FATAL,
(errmsg("incorrect checksum in control file")));
/*
* Do compatibility checking immediately. If the database isn't
* compatible with the backend executable, we want to abort before we can
* possibly do any damage.
*/
if (ControlFile->catalog_version_no != CATALOG_VERSION_NO)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized with CATALOG_VERSION_NO %d,"
" but the server was compiled with CATALOG_VERSION_NO %d.",
ControlFile->catalog_version_no, CATALOG_VERSION_NO),
errhint("It looks like you need to initdb.")));
if (ControlFile->maxAlign != MAXIMUM_ALIGNOF)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized with MAXALIGN %d,"
" but the server was compiled with MAXALIGN %d.",
ControlFile->maxAlign, MAXIMUM_ALIGNOF),
errhint("It looks like you need to initdb.")));
if (ControlFile->floatFormat != FLOATFORMAT_VALUE)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster appears to use a different floating-point number format than the server executable."),
errhint("It looks like you need to initdb.")));
if (ControlFile->blcksz != BLCKSZ)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized with BLCKSZ %d,"
" but the server was compiled with BLCKSZ %d.",
ControlFile->blcksz, BLCKSZ),
errhint("It looks like you need to recompile or initdb.")));
if (ControlFile->relseg_size != RELSEG_SIZE)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized with RELSEG_SIZE %d,"
" but the server was compiled with RELSEG_SIZE %d.",
ControlFile->relseg_size, RELSEG_SIZE),
errhint("It looks like you need to recompile or initdb.")));
if (ControlFile->xlog_blcksz != XLOG_BLCKSZ)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized with XLOG_BLCKSZ %d,"
" but the server was compiled with XLOG_BLCKSZ %d.",
ControlFile->xlog_blcksz, XLOG_BLCKSZ),
errhint("It looks like you need to recompile or initdb.")));
if (ControlFile->xlog_seg_size != XLOG_SEG_SIZE)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized with XLOG_SEG_SIZE %d,"
" but the server was compiled with XLOG_SEG_SIZE %d.",
ControlFile->xlog_seg_size, XLOG_SEG_SIZE),
errhint("It looks like you need to recompile or initdb.")));
if (ControlFile->nameDataLen != NAMEDATALEN)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized with NAMEDATALEN %d,"
" but the server was compiled with NAMEDATALEN %d.",
ControlFile->nameDataLen, NAMEDATALEN),
errhint("It looks like you need to recompile or initdb.")));
if (ControlFile->indexMaxKeys != INDEX_MAX_KEYS)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized with INDEX_MAX_KEYS %d,"
" but the server was compiled with INDEX_MAX_KEYS %d.",
ControlFile->indexMaxKeys, INDEX_MAX_KEYS),
errhint("It looks like you need to recompile or initdb.")));
if (ControlFile->toast_max_chunk_size != TOAST_MAX_CHUNK_SIZE)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized with TOAST_MAX_CHUNK_SIZE %d,"
" but the server was compiled with TOAST_MAX_CHUNK_SIZE %d.",
ControlFile->toast_max_chunk_size, (int) TOAST_MAX_CHUNK_SIZE),
errhint("It looks like you need to recompile or initdb.")));
#ifdef HAVE_INT64_TIMESTAMP
if (ControlFile->enableIntTimes != true)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized without HAVE_INT64_TIMESTAMP"
" but the server was compiled with HAVE_INT64_TIMESTAMP."),
errhint("It looks like you need to recompile or initdb.")));
#else
if (ControlFile->enableIntTimes != false)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized with HAVE_INT64_TIMESTAMP"
" but the server was compiled without HAVE_INT64_TIMESTAMP."),
errhint("It looks like you need to recompile or initdb.")));
#endif
#ifdef USE_FLOAT4_BYVAL
if (ControlFile->float4ByVal != true)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized without USE_FLOAT4_BYVAL"
" but the server was compiled with USE_FLOAT4_BYVAL."),
errhint("It looks like you need to recompile or initdb.")));
#else
if (ControlFile->float4ByVal != false)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized with USE_FLOAT4_BYVAL"
" but the server was compiled without USE_FLOAT4_BYVAL."),
errhint("It looks like you need to recompile or initdb.")));
#endif
#ifdef USE_FLOAT8_BYVAL
if (ControlFile->float8ByVal != true)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized without USE_FLOAT8_BYVAL"
" but the server was compiled with USE_FLOAT8_BYVAL."),
errhint("It looks like you need to recompile or initdb.")));
#else
if (ControlFile->float8ByVal != false)
ereport(FATAL,
(errmsg("database files are incompatible with server"),
errdetail("The database cluster was initialized with USE_FLOAT8_BYVAL"
" but the server was compiled without USE_FLOAT8_BYVAL."),
errhint("It looks like you need to recompile or initdb.")));
#endif
}
void
UpdateControlFile(void)
{
int fd;
INIT_CRC32(ControlFile->crc);
COMP_CRC32(ControlFile->crc,
(char *) ControlFile,
offsetof(ControlFileData, crc));
FIN_CRC32(ControlFile->crc);
fd = BasicOpenFile(XLOG_CONTROL_FILE,
O_RDWR | PG_BINARY,
S_IRUSR | S_IWUSR);
if (fd < 0)
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not open control file \"%s\": %m",
XLOG_CONTROL_FILE)));
errno = 0;
if (write(fd, ControlFile, sizeof(ControlFileData)) != sizeof(ControlFileData))
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not write to control file: %m")));
}
if (pg_fsync(fd) != 0)
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not fsync control file: %m")));
if (close(fd))
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not close control file: %m")));
}
/*
* 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->SharedRecoveryInProgress = true;
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.oldestXid = FirstNormalTransactionId;
checkPoint.oldestXidDB = TemplateDbOid;
checkPoint.time = (pg_time_t) time(NULL);
checkPoint.oldestActiveXid = InvalidTransactionId;
ShmemVariableCache->nextXid = checkPoint.nextXid;
ShmemVariableCache->nextOid = checkPoint.nextOid;
ShmemVariableCache->oidCount = 0;
MultiXactSetNextMXact(checkPoint.nextMulti, checkPoint.nextMultiOffset);
ShmemVariableCache->oldestXid = checkPoint.oldestXid;
ShmemVariableCache->oldestXidDB = checkPoint.oldestXidDB;
/* Set up the XLOG page header */
page->xlp_magic = XLOG_PAGE_MAGIC;
page->xlp_info = XLP_LONG_HEADER;
page->xlp_tli = ThisTimeLineID;
page->xlp_pageaddr.xlogid = 0;
page->xlp_pageaddr.xrecoff = 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_end_command") == 0)
{
recoveryEndCommand = pstrdup(tok2);
ereport(LOG,
(errmsg("recovery_end_command = '%s'",
recoveryEndCommand)));
}
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 (!parse_bool(tok2, &recoveryTargetInclusive))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("parameter \"recovery_target_inclusive\" requires a Boolean value")));
ereport(LOG,
(errmsg("recovery_target_inclusive = %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];
XLogRecPtr InvalidXLogRecPtr = {0, 0};
/*
* We are no longer in archive recovery state.
*/
InArchiveRecovery = false;
/*
* Update min recovery point one last time.
*/
UpdateMinRecoveryPoint(InvalidXLogRecPtr, true);
/*
* 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.
*
* Notify the archiver that the last WAL segment of the old timeline
* is ready to copy to archival storage. Otherwise, it is not archived
* for a while.
*/
if (endTLI != ThisTimeLineID)
{
XLogFileCopy(endLogId, endLogSeg,
endTLI, endLogId, endLogSeg);
if (XLogArchivingActive())
{
XLogFileName(xlogpath, endTLI, endLogId, endLogSeg);
XLogArchiveNotify(xlogpath);
}
}
}
/*
* Let's just make real sure there are not .ready or .done flags posted
* for the new segment.
*/
XLogFileName(xlogpath, ThisTimeLineID, endLogId, endLogSeg);
XLogArchiveCleanup(xlogpath);
/* Get rid of any remaining recovered timeline-history file, too */
snprintf(recoveryPath, MAXPGPATH, XLOGDIR "/RECOVERYHISTORY");
unlink(recoveryPath); /* ignore any error */
/*
* Rename the config file out of the way, so that we don't accidentally
* re-enter archive recovery mode in a subsequent crash.
*/
unlink(RECOVERY_COMMAND_DONE);
if (rename(RECOVERY_COMMAND_FILE, RECOVERY_COMMAND_DONE) != 0)
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not rename file \"%s\" to \"%s\": %m",
RECOVERY_COMMAND_FILE, RECOVERY_COMMAND_DONE)));
ereport(LOG,
(errmsg("archive recovery complete")));
}
/*
* For point-in-time recovery, this function decides whether we want to
* stop applying the XLOG at or after the current record.
*
* Returns TRUE if we are stopping, FALSE otherwise. On TRUE return,
* *includeThis is set TRUE if we should apply this record before stopping.
*
* We also track the timestamp of the latest applied COMMIT/ABORT record
* in recoveryLastXTime, for logging purposes.
* Also, some information is saved in recoveryStopXid et al for use in
* annotating the new timeline's history file.
*/
static bool
recoveryStopsHere(XLogRecord *record, bool *includeThis)
{
bool stopsHere;
uint8 record_info;
TimestampTz recordXtime;
/* We only consider stopping at COMMIT or ABORT records */
if (record->xl_rmid == RM_XACT_ID)
{
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;
}
else if (record->xl_rmid == RM_XLOG_ID)
{
record_info = record->xl_info & ~XLR_INFO_MASK;
if (record_info == XLOG_CHECKPOINT_SHUTDOWN ||
record_info == XLOG_CHECKPOINT_ONLINE)
{
CheckPoint checkPoint;
memcpy(&checkPoint, XLogRecGetData(record), sizeof(CheckPoint));
recoveryLastXTime = checkPoint.time;
}
/*
* We don't want to stop recovery on a checkpoint record, but we do
* want to update recoveryLastXTime. So return is unconditional.
*/
return false;
}
else
return false;
/* Do we have a PITR target at all? */
if (!recoveryTarget)
{
recoveryLastXTime = recordXtime;
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))));
}
if (recoveryStopAfter)
recoveryLastXTime = recordXtime;
}
else
recoveryLastXTime = recordXtime;
return stopsHere;
}
/*
* Returns bool with current recovery mode, a global state.
*/
Datum
pg_is_in_recovery(PG_FUNCTION_ARGS)
{
PG_RETURN_BOOL(RecoveryInProgress());
}
/*
* Returns timestamp of last recovered commit/abort record.
*/
TimestampTz
GetLatestXLogTime(void)
{
/* use volatile pointer to prevent code rearrangement */
volatile XLogCtlData *xlogctl = XLogCtl;
SpinLockAcquire(&xlogctl->info_lck);
recoveryLastXTime = xlogctl->recoveryLastXTime;
SpinLockRelease(&xlogctl->info_lck);
return recoveryLastXTime;
}
/*
* Note that text field supplied is a parameter name and does not require translation
*/
#define RecoveryRequiresIntParameter(param_name, currValue, checkpointValue) \
{ \
if (currValue < checkpointValue) \
ereport(ERROR, \
(errmsg("recovery connections cannot continue because " \
"%s = %u is a lower setting than on WAL source server (value was %u)", \
param_name, \
currValue, \
checkpointValue))); \
}
/*
* Check to see if required parameters are set high enough on this server
* for various aspects of recovery operation.
*/
static void
CheckRequiredParameterValues(CheckPoint checkPoint)
{
/* We ignore autovacuum_max_workers when we make this test. */
RecoveryRequiresIntParameter("max_connections",
MaxConnections, checkPoint.MaxConnections);
RecoveryRequiresIntParameter("max_prepared_xacts",
max_prepared_xacts, checkPoint.max_prepared_xacts);
RecoveryRequiresIntParameter("max_locks_per_xact",
max_locks_per_xact, checkPoint.max_locks_per_xact);
if (!checkPoint.XLogStandbyInfoMode)
ereport(ERROR,
(errmsg("recovery connections cannot start because the recovery_connections "
"parameter is disabled on the WAL source server")));
}
/*
* This must be called ONCE during postmaster or standalone-backend startup
*/
void
StartupXLOG(void)
{
XLogCtlInsert *Insert;
CheckPoint checkPoint;
bool wasShutdown;
bool reachedStopPoint = false;
bool haveBackupLabel = false;
XLogRecPtr RecPtr,
checkPointLoc,
backupStopLoc,
EndOfLog;
uint32 endLogId;
uint32 endLogSeg;
XLogRecord *record;
uint32 freespace;
TransactionId oldestActiveXID;
bool bgwriterLaunched = false;
bool backendsAllowed = false;
/*
* 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
/*
* Verify that pg_xlog and pg_xlog/archive_status exist. In cases where
* someone has performed a copy for PITR, these directories may have been
* excluded and need to be re-created.
*/
ValidateXLOGDirectoryStructure();
/*
* Clear out any old relcache cache files. This is *necessary* if we
* do any WAL replay, since that would probably result in the cache files
* being out of sync with database reality. In theory we could leave
* them in place if the database had been cleanly shut down, but it
* seems safest to just remove them always and let them be rebuilt
* during the first backend startup.
*/
RelationCacheInitFileRemove();
/*
* Initialize on the assumption we want to recover to the same timeline
* that's active according to pg_control.
*/
recoveryTargetTLI = ControlFile->checkPointCopy.ThisTimeLineID;
/*
* Check for recovery control file, and if so set up state for offline
* recovery
*/
readRecoveryCommandFile();
/* Now we can determine the list of expected TLIs */
expectedTLIs = readTimeLineHistory(recoveryTargetTLI);
/*
* If pg_control's timeline is not in expectedTLIs, then we cannot
* proceed: the backup is not part of the history of the requested
* timeline.
*/
if (!list_member_int(expectedTLIs,
(int) ControlFile->checkPointCopy.ThisTimeLineID))
ereport(FATAL,
(errmsg("requested timeline %u is not a child of database system timeline %u",
recoveryTargetTLI,
ControlFile->checkPointCopy.ThisTimeLineID)));
if (read_backup_label(&checkPointLoc, &backupStopLoc))
{
/*
* 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)));
ereport(DEBUG1,
(errmsg("oldest unfrozen transaction ID: %u, in database %u",
checkPoint.oldestXid, checkPoint.oldestXidDB)));
if (!TransactionIdIsNormal(checkPoint.nextXid))
ereport(PANIC,
(errmsg("invalid next transaction ID")));
ShmemVariableCache->nextXid = checkPoint.nextXid;
ShmemVariableCache->nextOid = checkPoint.nextOid;
ShmemVariableCache->oidCount = 0;
MultiXactSetNextMXact(checkPoint.nextMulti, checkPoint.nextMultiOffset);
ShmemVariableCache->oldestXid = checkPoint.oldestXid;
ShmemVariableCache->oldestXidDB = checkPoint.oldestXidDB;
/*
* We must replay WAL entries using the same TimeLineID they were created
* under, so temporarily adopt the TLI indicated by the checkpoint (see
* also xlog_redo()).
*/
ThisTimeLineID = checkPoint.ThisTimeLineID;
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 (backupStopLoc.xlogid != 0 || backupStopLoc.xrecoff != 0)
{
if (XLByteLT(ControlFile->minRecoveryPoint, backupStopLoc))
ControlFile->minRecoveryPoint = backupStopLoc;
}
ControlFile->time = (pg_time_t) time(NULL);
/* No need to hold ControlFileLock yet, we aren't up far enough */
UpdateControlFile();
/* initialize our local copy of minRecoveryPoint */
minRecoveryPoint = ControlFile->minRecoveryPoint;
/*
* Reset pgstat data, because it may be invalid after recovery.
*/
pgstat_reset_all();
/*
* If there was a backup label file, it's done its job and the info
* has now been propagated into pg_control. We must get rid of the
* label file so that if we crash during recovery, we'll pick up at
* the latest recovery restartpoint instead of going all the way back
* to the backup start point. It seems prudent though to just rename
* the file out of the way rather than delete it completely.
*/
if (haveBackupLabel)
{
unlink(BACKUP_LABEL_OLD);
if (rename(BACKUP_LABEL_FILE, BACKUP_LABEL_OLD) != 0)
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not rename file \"%s\" to \"%s\": %m",
BACKUP_LABEL_FILE, BACKUP_LABEL_OLD)));
}
/*
* Initialize recovery connections, if enabled. We won't let backends
* in yet, not until we've reached the min recovery point specified
* in control file and we've established a recovery snapshot from a
* running-xacts WAL record.
*/
if (InArchiveRecovery && XLogRequestRecoveryConnections)
{
TransactionId *xids;
int nxids;
CheckRequiredParameterValues(checkPoint);
ereport(LOG,
(errmsg("initializing recovery connections")));
InitRecoveryTransactionEnvironment();
if (wasShutdown)
oldestActiveXID = PrescanPreparedTransactions(&xids, &nxids);
else
oldestActiveXID = checkPoint.oldestActiveXid;
Assert(TransactionIdIsValid(oldestActiveXID));
/* Startup commit log and related stuff */
StartupCLOG();
StartupSUBTRANS(oldestActiveXID);
StartupMultiXact();
ProcArrayInitRecoveryInfo(oldestActiveXID);
}
/* Initialize resource managers */
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;
bool reachedMinRecoveryPoint = false;
ErrorContextCallback errcontext;
/* use volatile pointer to prevent code rearrangement */
volatile XLogCtlData *xlogctl = XLogCtl;
/* initialize shared replayEndRecPtr */
SpinLockAcquire(&xlogctl->info_lck);
xlogctl->replayEndRecPtr = ReadRecPtr;
SpinLockRelease(&xlogctl->info_lck);
InRedo = true;
if (minRecoveryPoint.xlogid == 0 && minRecoveryPoint.xrecoff == 0)
ereport(LOG,
(errmsg("redo starts at %X/%X",
ReadRecPtr.xlogid, ReadRecPtr.xrecoff)));
else
ereport(LOG,
(errmsg("redo starts at %X/%X, consistency will be reached at %X/%X",
ReadRecPtr.xlogid, ReadRecPtr.xrecoff,
minRecoveryPoint.xlogid, minRecoveryPoint.xrecoff)));
/*
* Let postmaster know we've started redo now, so that it can
* launch bgwriter to perform restartpoints. We don't bother
* during crash recovery as restartpoints can only be performed
* during archive recovery. And we'd like to keep crash recovery
* simple, to avoid introducing bugs that could you from
* recovering after crash.
*
* After this point, we can no longer assume that we're the only
* process in addition to postmaster! Also, fsync requests are
* subsequently to be handled by the bgwriter, not locally.
*/
if (InArchiveRecovery && IsUnderPostmaster)
{
SetForwardFsyncRequests();
SendPostmasterSignal(PMSIGNAL_RECOVERY_STARTED);
bgwriterLaunched = true;
}
/*
* main redo apply loop
*/
do
{
#ifdef WAL_DEBUG
if (XLOG_DEBUG ||
(rmid == RM_XACT_ID && trace_recovery_messages <= DEBUG2) ||
(rmid != RM_XACT_ID && trace_recovery_messages <= DEBUG3))
{
StringInfoData buf;
initStringInfo(&buf);
appendStringInfo(&buf, "REDO @ %X/%X; LSN %X/%X: ",
ReadRecPtr.xlogid, ReadRecPtr.xrecoff,
EndRecPtr.xlogid, EndRecPtr.xrecoff);
xlog_outrec(&buf, record);
appendStringInfo(&buf, " - ");
RmgrTable[record->xl_rmid].rm_desc(&buf,
record->xl_info,
XLogRecGetData(record));
elog(LOG, "%s", buf.data);
pfree(buf.data);
}
#endif
/*
* Check if we were requested to re-read config file.
*/
if (got_SIGHUP)
{
got_SIGHUP = false;
ProcessConfigFile(PGC_SIGHUP);
}
/*
* Have we passed our safe starting point?
*/
if (!reachedMinRecoveryPoint &&
XLByteLE(minRecoveryPoint, EndRecPtr))
{
reachedMinRecoveryPoint = true;
ereport(LOG,
(errmsg("consistent recovery state reached at %X/%X",
EndRecPtr.xlogid, EndRecPtr.xrecoff)));
}
/*
* Have we got a valid starting snapshot that will allow
* queries to be run? If so, we can tell postmaster that
* the database is consistent now, enabling connections.
*/
if (standbyState == STANDBY_SNAPSHOT_READY &&
!backendsAllowed &&
reachedMinRecoveryPoint &&
IsUnderPostmaster)
{
backendsAllowed = true;
SendPostmasterSignal(PMSIGNAL_RECOVERY_CONSISTENT);
}
/*
* 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);
}
/*
* Update shared replayEndRecPtr before replaying this record,
* so that XLogFlush will update minRecoveryPoint correctly.
*/
SpinLockAcquire(&xlogctl->info_lck);
xlogctl->replayEndRecPtr = EndRecPtr;
xlogctl->recoveryLastXTime = recoveryLastXTime;
SpinLockRelease(&xlogctl->info_lck);
/* In Hot Standby mode, keep track of XIDs we've seen */
if (InHotStandby && TransactionIdIsValid(record->xl_xid))
RecordKnownAssignedTransactionIds(record->xl_xid);
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. Note: it is indeed okay to look at the local variable
* minRecoveryPoint here, even though ControlFile->minRecoveryPoint might
* be further ahead --- ControlFile->minRecoveryPoint cannot have been
* advanced beyond the WAL we processed.
*/
if (InRecovery && XLByteLT(EndOfLog, minRecoveryPoint))
{
if (reachedStopPoint) /* stopped because of stop request */
ereport(FATAL,
(errmsg("requested recovery stop point is before consistent recovery point")));
else /* ran off end of WAL */
ereport(FATAL,
(errmsg("WAL ends before consistent recovery point")));
}
/*
* Consider whether we need to assign a new timeline ID.
*
* If we are doing an archive recovery, we always assign a new ID. This
* handles a couple of issues. If we stopped short of the end of WAL
* during recovery, then we are clearly generating a new timeline and must
* assign it a unique new ID. Even if we ran to the end, modifying the
* current last segment is problematic because it may result in trying to
* overwrite an already-archived copy of that segment, and we encourage
* DBAs to make their archive_commands reject that. We can dodge the
* problem by making the new active segment have a new timeline ID.
*
* In a normal crash recovery, we can just extend the timeline we were in.
*/
if (InArchiveRecovery)
{
ThisTimeLineID = findNewestTimeLine(recoveryTargetTLI) + 1;
ereport(LOG,
(errmsg("selected new timeline ID: %u", ThisTimeLineID)));
writeTimeLineHistory(ThisTimeLineID, recoveryTargetTLI,
curFileTLI, endLogId, endLogSeg);
}
/* Save the selected TimeLineID in shared memory, too */
XLogCtl->ThisTimeLineID = ThisTimeLineID;
/*
* We are now done reading the old WAL. Turn off archive fetching if it
* was active, and make a writable copy of the last WAL segment. (Note
* that we also have a copy of the last block of the old WAL in readBuf;
* we will use that below.)
*/
if (InArchiveRecovery)
exitArchiveRecovery(curFileTLI, endLogId, endLogSeg);
/*
* Prepare to write WAL starting at EndOfLog position, and init xlog
* buffer cache using the block containing the last record from the
* previous incarnation.
*/
openLogId = endLogId;
openLogSeg = endLogSeg;
openLogFile = XLogFileOpen(openLogId, openLogSeg);
openLogOff = 0;
Insert = &XLogCtl->Insert;
Insert->PrevRecord = LastRec;
XLogCtl->xlblocks[0].xlogid = openLogId;
XLogCtl->xlblocks[0].xrecoff =
((EndOfLog.xrecoff - 1) / XLOG_BLCKSZ + 1) * XLOG_BLCKSZ;
/*
* Tricky point here: readBuf contains the *last* block that the LastRec
* record spans, not the one it starts in. The last block is indeed the
* one we want to use.
*/
Assert(readOff == (XLogCtl->xlblocks[0].xrecoff - XLOG_BLCKSZ) % XLogSegSize);
memcpy((char *) Insert->currpage, readBuf, XLOG_BLCKSZ);
Insert->currpos = (char *) Insert->currpage +
(EndOfLog.xrecoff + XLOG_BLCKSZ - XLogCtl->xlblocks[0].xrecoff);
LogwrtResult.Write = LogwrtResult.Flush = EndOfLog;
XLogCtl->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(NULL, NULL);
if (InRecovery)
{
int rmid;
/*
* Resource managers might need to write WAL records, eg, to record
* index cleanup actions. So temporarily enable XLogInsertAllowed in
* this process only.
*/
LocalSetXLogInsertAllowed();
/*
* Allow resource managers to do any required cleanup.
*/
for (rmid = 0; rmid <= RM_MAX_ID; rmid++)
{
if (RmgrTable[rmid].rm_cleanup != NULL)
RmgrTable[rmid].rm_cleanup();
}
/* Disallow XLogInsert again */
LocalXLogInsertAllowed = -1;
/*
* Check to see if the XLOG sequence contained any unresolved
* references to uninitialized pages.
*/
XLogCheckInvalidPages();
/*
* Perform a checkpoint to update all our recovery activity to disk.
*
* Note that we write a shutdown checkpoint rather than an on-line
* one. This is not particularly critical, but since we may be
* assigning a new TLI, using a shutdown checkpoint allows us to have
* the rule that TLI only changes in shutdown checkpoints, which
* allows some extra error checking in xlog_redo.
*/
if (bgwriterLaunched)
RequestCheckpoint(CHECKPOINT_END_OF_RECOVERY |
CHECKPOINT_IMMEDIATE |
CHECKPOINT_WAIT);
else
CreateCheckPoint(CHECKPOINT_END_OF_RECOVERY | CHECKPOINT_IMMEDIATE);
/*
* And finally, execute the recovery_end_command, if any.
*/
if (recoveryEndCommand)
ExecuteRecoveryEndCommand();
}
/*
* Preallocate additional log files, if wanted.
*/
PreallocXlogFiles(EndOfLog);
/*
* Okay, we're officially UP.
*/
InRecovery = false;
LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
ControlFile->state = DB_IN_PRODUCTION;
ControlFile->time = (pg_time_t) time(NULL);
UpdateControlFile();
LWLockRelease(ControlFileLock);
/* start the archive_timeout timer running */
XLogCtl->Write.lastSegSwitchTime = (pg_time_t) time(NULL);
/* 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. In hot standby mode
* we did this already before WAL replay.
*/
if (standbyState == STANDBY_DISABLED)
{
StartupCLOG();
StartupSUBTRANS(oldestActiveXID);
StartupMultiXact();
}
/* Reload shared-memory state for prepared transactions */
RecoverPreparedTransactions();
/*
* Shutdown the recovery environment. This must occur after
* RecoverPreparedTransactions(), see notes for lock_twophase_recover()
*/
if (standbyState != STANDBY_DISABLED)
ShutdownRecoveryTransactionEnvironment();
/* Shut down readFile facility, free space */
if (readFile >= 0)
{
close(readFile);
readFile = -1;
}
if (readBuf)
{
free(readBuf);
readBuf = NULL;
}
if (readRecordBuf)
{
free(readRecordBuf);
readRecordBuf = NULL;
readRecordBufSize = 0;
}
/*
* All done. Allow backends to write WAL. (Although the bool flag is
* probably atomic in itself, we use the info_lck here to ensure that
* there are no race conditions concerning visibility of other recent
* updates to shared memory.)
*/
{
/* use volatile pointer to prevent code rearrangement */
volatile XLogCtlData *xlogctl = XLogCtl;
SpinLockAcquire(&xlogctl->info_lck);
xlogctl->SharedRecoveryInProgress = false;
SpinLockRelease(&xlogctl->info_lck);
}
}
/*
* Is the system still in recovery?
*
* Unlike testing InRecovery, this works in any process that's connected to
* shared memory.
*
* As a side-effect, we initialize the local TimeLineID and RedoRecPtr
* variables the first time we see that recovery is finished.
*/
bool
RecoveryInProgress(void)
{
/*
* We check shared state each time only until we leave recovery mode.
* We can't re-enter recovery, so there's no need to keep checking after
* the shared variable has once been seen false.
*/
if (!LocalRecoveryInProgress)
return false;
else
{
/* use volatile pointer to prevent code rearrangement */
volatile XLogCtlData *xlogctl = XLogCtl;
/* spinlock is essential on machines with weak memory ordering! */
SpinLockAcquire(&xlogctl->info_lck);
LocalRecoveryInProgress = xlogctl->SharedRecoveryInProgress;
SpinLockRelease(&xlogctl->info_lck);
/*
* Initialize TimeLineID and RedoRecPtr when we discover that recovery
* is finished. InitPostgres() relies upon this behaviour to ensure
* that InitXLOGAccess() is called at backend startup. (If you change
* this, see also LocalSetXLogInsertAllowed.)
*/
if (!LocalRecoveryInProgress)
InitXLOGAccess();
return LocalRecoveryInProgress;
}
}
/*
* Is this process allowed to insert new WAL records?
*
* Ordinarily this is essentially equivalent to !RecoveryInProgress().
* But we also have provisions for forcing the result "true" or "false"
* within specific processes regardless of the global state.
*/
bool
XLogInsertAllowed(void)
{
/*
* If value is "unconditionally true" or "unconditionally false",
* just return it. This provides the normal fast path once recovery
* is known done.
*/
if (LocalXLogInsertAllowed >= 0)
return (bool) LocalXLogInsertAllowed;
/*
* Else, must check to see if we're still in recovery.
*/
if (RecoveryInProgress())
return false;
/*
* On exit from recovery, reset to "unconditionally true", since there
* is no need to keep checking.
*/
LocalXLogInsertAllowed = 1;
return true;
}
/*
* Make XLogInsertAllowed() return true in the current process only.
*
* Note: it is allowed to switch LocalXLogInsertAllowed back to -1 later,
* and even call LocalSetXLogInsertAllowed() again after that.
*/
static void
LocalSetXLogInsertAllowed(void)
{
Assert(LocalXLogInsertAllowed == -1);
LocalXLogInsertAllowed = 1;
/* Initialize as RecoveryInProgress() would do when switching state */
InitXLOGAccess();
}
/*
* Subroutine to try to fetch and validate a prior checkpoint record.
*
* whichChkpt identifies the checkpoint (merely for reporting purposes).
* 1 for "primary", 2 for "secondary", 0 for "other" (backup_label)
*/
static XLogRecord *
ReadCheckpointRecord(XLogRecPtr RecPtr, int whichChkpt)
{
XLogRecord *record;
if (!XRecOffIsValid(RecPtr.xrecoff))
{
switch (whichChkpt)
{
case 1:
ereport(LOG,
(errmsg("invalid primary checkpoint link in control file")));
break;
case 2:
ereport(LOG,
(errmsg("invalid secondary checkpoint link in control file")));
break;
default:
ereport(LOG,
(errmsg("invalid checkpoint link in backup_label file")));
break;
}
return NULL;
}
record = ReadRecord(&RecPtr, LOG);
if (record == NULL)
{
switch (whichChkpt)
{
case 1:
ereport(LOG,
(errmsg("invalid primary checkpoint record")));
break;
case 2:
ereport(LOG,
(errmsg("invalid secondary checkpoint record")));
break;
default:
ereport(LOG,
(errmsg("invalid checkpoint record")));
break;
}
return NULL;
}
if (record->xl_rmid != RM_XLOG_ID)
{
switch (whichChkpt)
{
case 1:
ereport(LOG,
(errmsg("invalid resource manager ID in primary checkpoint record")));
break;
case 2:
ereport(LOG,
(errmsg("invalid resource manager ID in secondary checkpoint record")));
break;
default:
ereport(LOG,
(errmsg("invalid resource manager ID in checkpoint record")));
break;
}
return NULL;
}
if (record->xl_info != XLOG_CHECKPOINT_SHUTDOWN &&
record->xl_info != XLOG_CHECKPOINT_ONLINE)
{
switch (whichChkpt)
{
case 1:
ereport(LOG,
(errmsg("invalid xl_info in primary checkpoint record")));
break;
case 2:
ereport(LOG,
(errmsg("invalid xl_info in secondary checkpoint record")));
break;
default:
ereport(LOG,
(errmsg("invalid xl_info in checkpoint record")));
break;
}
return NULL;
}
if (record->xl_len != sizeof(CheckPoint) ||
record->xl_tot_len != SizeOfXLogRecord + sizeof(CheckPoint))
{
switch (whichChkpt)
{
case 1:
ereport(LOG,
(errmsg("invalid length of primary checkpoint record")));
break;
case 2:
ereport(LOG,
(errmsg("invalid length of secondary checkpoint record")));
break;
default:
ereport(LOG,
(errmsg("invalid length of checkpoint record")));
break;
}
return NULL;
}
return record;
}
/*
* This must be called during startup of a backend process, except that
* it need not be called in a standalone backend (which does StartupXLOG
* instead). We need to initialize the local copies of ThisTimeLineID and
* RedoRecPtr.
*
* Note: before Postgres 8.0, we went to some effort to keep the postmaster
* process's copies of ThisTimeLineID and RedoRecPtr valid too. This was
* unnecessary however, since the postmaster itself never touches XLOG anyway.
*/
void
InitXLOGAccess(void)
{
/* ThisTimeLineID doesn't change so we need no lock to copy it */
ThisTimeLineID = XLogCtl->ThisTimeLineID;
Assert(ThisTimeLineID != 0 || IsBootstrapProcessingMode());
/* Use GetRedoRecPtr to copy the RedoRecPtr safely */
(void) GetRedoRecPtr();
}
/*
* Once spawned, a backend may update its local RedoRecPtr from
* XLogCtl->Insert.RedoRecPtr; it must hold the insert lock or info_lck
* to do so. This is done in XLogInsert() or GetRedoRecPtr().
*/
XLogRecPtr
GetRedoRecPtr(void)
{
/* use volatile pointer to prevent code rearrangement */
volatile XLogCtlData *xlogctl = XLogCtl;
SpinLockAcquire(&xlogctl->info_lck);
Assert(XLByteLE(RedoRecPtr, xlogctl->Insert.RedoRecPtr));
RedoRecPtr = xlogctl->Insert.RedoRecPtr;
SpinLockRelease(&xlogctl->info_lck);
return RedoRecPtr;
}
/*
* GetInsertRecPtr -- Returns the current insert position.
*
* NOTE: The value *actually* returned is the position of the last full
* xlog page. It lags behind the real insert position by at most 1 page.
* For that, we don't need to acquire WALInsertLock which can be quite
* heavily contended, and an approximation is enough for the current
* usage of this function.
*/
XLogRecPtr
GetInsertRecPtr(void)
{
/* use volatile pointer to prevent code rearrangement */
volatile XLogCtlData *xlogctl = XLogCtl;
XLogRecPtr recptr;
SpinLockAcquire(&xlogctl->info_lck);
recptr = xlogctl->LogwrtRqst.Write;
SpinLockRelease(&xlogctl->info_lck);
return recptr;
}
/*
* 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")));
if (RecoveryInProgress())
CreateRestartPoint(CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_IMMEDIATE);
else
{
/*
* If archiving is enabled, rotate the last XLOG file so that all the
* remaining records are archived (postmaster wakes up the archiver
* process one more time at the end of shutdown). The checkpoint
* record will go to the next XLOG file and won't be archived (yet).
*/
if (XLogArchivingActive() && XLogArchiveCommandSet())
RequestXLogSwitch();
CreateCheckPoint(CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_IMMEDIATE);
}
ShutdownCLOG();
ShutdownSUBTRANS();
ShutdownMultiXact();
ereport(LOG,
(errmsg("database system is shut down")));
}
/*
* Log start of a checkpoint.
*/
static void
LogCheckpointStart(int flags, bool restartpoint)
{
const char *msg;
/*
* XXX: This is hopelessly untranslatable. We could call gettext_noop for
* the main message, but what about all the flags?
*/
if (restartpoint)
msg = "restartpoint starting:%s%s%s%s%s%s%s";
else
msg = "checkpoint starting:%s%s%s%s%s%s%s";
elog(LOG, msg,
(flags & CHECKPOINT_IS_SHUTDOWN) ? " shutdown" : "",
(flags & CHECKPOINT_END_OF_RECOVERY) ? " end-of-recovery" : "",
(flags & CHECKPOINT_IMMEDIATE) ? " immediate" : "",
(flags & CHECKPOINT_FORCE) ? " force" : "",
(flags & CHECKPOINT_WAIT) ? " wait" : "",
(flags & CHECKPOINT_CAUSE_XLOG) ? " xlog" : "",
(flags & CHECKPOINT_CAUSE_TIME) ? " time" : "");
}
/*
* Log end of a checkpoint.
*/
static void
LogCheckpointEnd(bool restartpoint)
{
long write_secs,
sync_secs,
total_secs;
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);
if (restartpoint)
elog(LOG, "restartpoint complete: wrote %d buffers (%.1f%%); "
"write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s",
CheckpointStats.ckpt_bufs_written,
(double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers,
write_secs, write_usecs / 1000,
sync_secs, sync_usecs / 1000,
total_secs, total_usecs / 1000);
else
elog(LOG, "checkpoint complete: wrote %d buffers (%.1f%%); "
"%d transaction log file(s) added, %d removed, %d recycled; "
"write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s",
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_END_OF_RECOVERY: checkpoint is for end of WAL recovery.
* CHECKPOINT_IMMEDIATE: finish the checkpoint ASAP,
* ignoring checkpoint_completion_target parameter.
* CHECKPOINT_FORCE: force a checkpoint even if no XLOG activity has occured
* since the last one (implied by CHECKPOINT_IS_SHUTDOWN or
* CHECKPOINT_END_OF_RECOVERY).
*
* Note: flags contains other bits, of interest here only for logging purposes.
* In particular note that this routine is synchronous and does not pay
* attention to CHECKPOINT_WAIT.
*/
void
CreateCheckPoint(int flags)
{
bool shutdown;
CheckPoint checkPoint;
XLogRecPtr recptr;
XLogCtlInsert *Insert = &XLogCtl->Insert;
XLogRecData rdata;
uint32 freespace;
uint32 _logId;
uint32 _logSeg;
TransactionId *inCommitXids;
int nInCommit;
/*
* An end-of-recovery checkpoint is really a shutdown checkpoint, just
* issued at a different time.
*/
if (flags & (CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_END_OF_RECOVERY))
shutdown = true;
else
shutdown = false;
/* sanity check */
if (RecoveryInProgress() && (flags & CHECKPOINT_END_OF_RECOVERY) == 0)
elog(ERROR, "can't create a checkpoint during recovery");
/*
* Acquire CheckpointLock to ensure only one checkpoint happens at a time.
* (This is just pro forma, since in the present system structure there is
* only one process that is allowed to issue checkpoints at any given
* time.)
*/
LWLockAcquire(CheckpointLock, LW_EXCLUSIVE);
/*
* Prepare to accumulate statistics.
*
* Note: because it is possible for log_checkpoints to change while a
* checkpoint proceeds, we always accumulate stats, even if
* log_checkpoints is currently off.
*/
MemSet(&CheckpointStats, 0, sizeof(CheckpointStats));
CheckpointStats.ckpt_start_t = GetCurrentTimestamp();
/*
* Use a critical section to force system panic if we have trouble.
*/
START_CRIT_SECTION();
if (shutdown)
{
LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
ControlFile->state = DB_SHUTDOWNING;
ControlFile->time = (pg_time_t) time(NULL);
UpdateControlFile();
LWLockRelease(ControlFileLock);
}
/*
* Let smgr prepare for checkpoint; this has to happen before we determine
* the REDO pointer. Note that smgr must not do anything that'd have to
* be undone if we decide no checkpoint is needed.
*/
smgrpreckpt();
/* Begin filling in the checkpoint WAL record */
MemSet(&checkPoint, 0, sizeof(checkPoint));
checkPoint.time = (pg_time_t) time(NULL);
/* Set important parameter values for use when replaying WAL */
checkPoint.MaxConnections = MaxConnections;
checkPoint.max_prepared_xacts = max_prepared_xacts;
checkPoint.max_locks_per_xact = max_locks_per_xact;
checkPoint.XLogStandbyInfoMode = XLogStandbyInfoActive();
/*
* We must hold WALInsertLock while examining insert state to determine
* the checkpoint REDO pointer.
*/
LWLockAcquire(WALInsertLock, LW_EXCLUSIVE);
/*
* If this isn't a shutdown or forced checkpoint, and we have not inserted
* any XLOG records since the start of the last checkpoint, skip the
* checkpoint. The idea here is to avoid inserting duplicate checkpoints
* when the system is idle. That wastes log space, and more importantly it
* exposes us to possible loss of both current and previous checkpoint
* records if the machine crashes just as we're writing the update.
* (Perhaps it'd make even more sense to checkpoint only when the previous
* checkpoint record is in a different xlog page?)
*
* We have to make two tests to determine that nothing has happened since
* the start of the last checkpoint: current insertion point must match
* the end of the last checkpoint record, and its redo pointer must point
* to itself.
*/
if ((flags & (CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_END_OF_RECOVERY |
CHECKPOINT_FORCE)) == 0)
{
XLogRecPtr curInsert;
INSERT_RECPTR(curInsert, Insert, Insert->curridx);
if (curInsert.xlogid == ControlFile->checkPoint.xlogid &&
curInsert.xrecoff == ControlFile->checkPoint.xrecoff +
MAXALIGN(SizeOfXLogRecord + sizeof(CheckPoint)) &&
ControlFile->checkPoint.xlogid ==
ControlFile->checkPointCopy.redo.xlogid &&
ControlFile->checkPoint.xrecoff ==
ControlFile->checkPointCopy.redo.xrecoff)
{
LWLockRelease(WALInsertLock);
LWLockRelease(CheckpointLock);
END_CRIT_SECTION();
return;
}
}
/*
* An end-of-recovery checkpoint is created before anyone is allowed to
* write WAL. To allow us to write the checkpoint record, temporarily
* enable XLogInsertAllowed. (This also ensures ThisTimeLineID is
* initialized, which we need here and in AdvanceXLInsertBuffer.)
*/
if (flags & CHECKPOINT_END_OF_RECOVERY)
LocalSetXLogInsertAllowed();
checkPoint.ThisTimeLineID = ThisTimeLineID;
/*
* Compute new REDO record ptr = location of next XLOG record.
*
* NB: this is NOT necessarily where the checkpoint record itself will be,
* since other backends may insert more XLOG records while we're off doing
* the buffer flush work. Those XLOG records are logically after the
* checkpoint, even though physically before it. Got that?
*/
freespace = INSERT_FREESPACE(Insert);
if (freespace < SizeOfXLogRecord)
{
(void) AdvanceXLInsertBuffer(false);
/* OK to ignore update return flag, since we will do flush anyway */
freespace = INSERT_FREESPACE(Insert);
}
INSERT_RECPTR(checkPoint.redo, Insert, Insert->curridx);
/*
* Here we update the shared RedoRecPtr for future XLogInsert calls; this
* must be done while holding the insert lock AND the info_lck.
*
* Note: if we fail to complete the checkpoint, RedoRecPtr will be left
* pointing past where it really needs to point. This is okay; the only
* consequence is that XLogInsert might back up whole buffers that it
* didn't really need to. We can't postpone advancing RedoRecPtr because
* XLogInserts that happen while we are dumping buffers must assume that
* their buffer changes are not included in the checkpoint.
*/
{
/* use volatile pointer to prevent code rearrangement */
volatile XLogCtlData *xlogctl = XLogCtl;
SpinLockAcquire(&xlogctl->info_lck);
RedoRecPtr = xlogctl->Insert.RedoRecPtr = checkPoint.redo;
SpinLockRelease(&xlogctl->info_lck);
}
/*
* Now we can release WAL insert lock, allowing other xacts to proceed
* while we are flushing disk buffers.
*/
LWLockRelease(WALInsertLock);
/*
* If enabled, log checkpoint start. We postpone this until now so as not
* to log anything if we decided to skip the checkpoint.
*/
if (log_checkpoints)
LogCheckpointStart(flags, false);
TRACE_POSTGRESQL_CHECKPOINT_START(flags);
/*
* Before flushing data, we must wait for any transactions that are
* currently in their commit critical sections. If an xact inserted its
* commit record into XLOG just before the REDO point, then a crash
* restart from the REDO point would not replay that record, which means
* that our flushing had better include the xact's update of pg_clog. So
* we wait till he's out of his commit critical section before proceeding.
* See notes in RecordTransactionCommit().
*
* Because we've already released WALInsertLock, this test is a bit fuzzy:
* it is possible that we will wait for xacts we didn't really need to
* wait for. But the delay should be short and it seems better to make
* checkpoint take a bit longer than to hold locks longer than necessary.
* (In fact, the whole reason we have this issue is that xact.c does
* commit record XLOG insertion and clog update as two separate steps
* protected by different locks, but again that seems best on grounds of
* minimizing lock contention.)
*
* A transaction that has not yet set inCommit when we look cannot be at
* risk, since he's not inserted his commit record yet; and one that's
* already cleared it is not at risk either, since he's done fixing clog
* and we will correctly flush the update below. So we cannot miss any
* xacts we need to wait for.
*/
nInCommit = GetTransactionsInCommit(&inCommitXids);
if (nInCommit > 0)
{
do
{
pg_usleep(10000L); /* wait for 10 msec */
} while (HaveTransactionsInCommit(inCommitXids, nInCommit));
}
pfree(inCommitXids);
/*
* Get the other info we need for the checkpoint record.
*/
LWLockAcquire(XidGenLock, LW_SHARED);
checkPoint.nextXid = ShmemVariableCache->nextXid;
checkPoint.oldestXid = ShmemVariableCache->oldestXid;
checkPoint.oldestXidDB = ShmemVariableCache->oldestXidDB;
LWLockRelease(XidGenLock);
/* Increase XID epoch if we've wrapped around since last checkpoint */
checkPoint.nextXidEpoch = ControlFile->checkPointCopy.nextXidEpoch;
if (checkPoint.nextXid < ControlFile->checkPointCopy.nextXid)
checkPoint.nextXidEpoch++;
LWLockAcquire(OidGenLock, LW_SHARED);
checkPoint.nextOid = ShmemVariableCache->nextOid;
if (!shutdown)
checkPoint.nextOid += ShmemVariableCache->oidCount;
LWLockRelease(OidGenLock);
MultiXactGetCheckptMulti(shutdown,
&checkPoint.nextMulti,
&checkPoint.nextMultiOffset);
/*
* Having constructed the checkpoint record, ensure all shmem disk buffers
* and commit-log buffers are flushed to disk.
*
* This I/O could fail for various reasons. If so, we will fail to
* complete the checkpoint, but there is no reason to force a system
* panic. Accordingly, exit critical section while doing it.
*/
END_CRIT_SECTION();
CheckPointGuts(checkPoint.redo, flags);
/*
* Take a snapshot of running transactions and write this to WAL.
* This allows us to reconstruct the state of running transactions
* during archive recovery, if required. Skip, if this info disabled.
*
* If we are shutting down, or Startup process is completing crash
* recovery we don't need to write running xact data.
*
* Update checkPoint.nextXid since we have a later value
*/
if (!shutdown && XLogStandbyInfoActive())
LogStandbySnapshot(&checkPoint.oldestActiveXid, &checkPoint.nextXid);
else
checkPoint.oldestActiveXid = InvalidTransactionId;
START_CRIT_SECTION();
/*
* Now insert the checkpoint record into XLOG.
*/
rdata.data = (char *) (&checkPoint);
rdata.len = sizeof(checkPoint);
rdata.buffer = InvalidBuffer;
rdata.next = NULL;
recptr = XLogInsert(RM_XLOG_ID,
shutdown ? XLOG_CHECKPOINT_SHUTDOWN :
XLOG_CHECKPOINT_ONLINE,
&rdata);
XLogFlush(recptr);
/*
* We mustn't write any new WAL after a shutdown checkpoint, or it will
* be overwritten at next startup. No-one should even try, this just
* allows sanity-checking. In the case of an end-of-recovery checkpoint,
* we want to just temporarily disable writing until the system has exited
* recovery.
*/
if (shutdown)
{
if (flags & CHECKPOINT_END_OF_RECOVERY)
LocalXLogInsertAllowed = -1; /* return to "check" state */
else
LocalXLogInsertAllowed = 0; /* never again write WAL */
}
/*
* We now have ProcLastRecPtr = start of actual checkpoint record, recptr
* = end of actual checkpoint record.
*/
if (shutdown && !XLByteEQ(checkPoint.redo, ProcLastRecPtr))
ereport(PANIC,
(errmsg("concurrent transaction log activity while database system is shutting down")));
/*
* Select point at which we can truncate the log, which we base on the
* prior checkpoint's earliest info.
*/
XLByteToSeg(ControlFile->checkPointCopy.redo, _logId, _logSeg);
/*
* Update the control file.
*/
LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
if (shutdown)
ControlFile->state = DB_SHUTDOWNED;
ControlFile->prevCheckPoint = ControlFile->checkPoint;
ControlFile->checkPoint = ProcLastRecPtr;
ControlFile->checkPointCopy = checkPoint;
ControlFile->time = (pg_time_t) time(NULL);
/* crash recovery should always recover to the end of WAL */
MemSet(&ControlFile->minRecoveryPoint, 0, sizeof(XLogRecPtr));
UpdateControlFile();
LWLockRelease(ControlFileLock);
/* Update shared-memory copy of checkpoint XID/epoch */
{
/* use volatile pointer to prevent code rearrangement */
volatile XLogCtlData *xlogctl = XLogCtl;
SpinLockAcquire(&xlogctl->info_lck);
xlogctl->ckptXidEpoch = checkPoint.nextXidEpoch;
xlogctl->ckptXid = checkPoint.nextXid;
SpinLockRelease(&xlogctl->info_lck);
}
/*
* We are now done with critical updates; no need for system panic if we
* have trouble while fooling with old log segments.
*/
END_CRIT_SECTION();
/*
* Let smgr do post-checkpoint cleanup (eg, deleting old files).
*/
smgrpostckpt();
/*
* Delete old log files (those no longer needed even for previous
* checkpoint).
*/
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 (!RecoveryInProgress())
TruncateSUBTRANS(GetOldestXmin(true, false));
/* All real work is done, but log before releasing lock. */
if (log_checkpoints)
LogCheckpointEnd(false);
TRACE_POSTGRESQL_CHECKPOINT_DONE(CheckpointStats.ckpt_bufs_written,
NBuffers,
CheckpointStats.ckpt_segs_added,
CheckpointStats.ckpt_segs_removed,
CheckpointStats.ckpt_segs_recycled);
LWLockRelease(CheckpointLock);
}
/*
* Flush all data in shared memory to disk, and fsync
*
* This is the common code shared between regular checkpoints and
* recovery restartpoints.
*/
static void
CheckPointGuts(XLogRecPtr checkPointRedo, int flags)
{
CheckPointCLOG();
CheckPointSUBTRANS();
CheckPointMultiXact();
CheckPointBuffers(flags); /* performs all required fsyncs */
/* We deliberately delay 2PC checkpointing as long as possible */
CheckPointTwoPhase(checkPointRedo);
}
/*
* Save a checkpoint for recovery restart if appropriate
*
* This function is called each time a checkpoint record is read from XLOG.
* It must determine whether the checkpoint represents a safe restartpoint or
* not. If so, the checkpoint record is stashed in shared memory so that
* CreateRestartPoint can consult it. (Note that the latter function is
* executed by the bgwriter, while this one will be executed by the startup
* process.)
*/
static void
RecoveryRestartPoint(const CheckPoint *checkPoint)
{
int rmid;
/* use volatile pointer to prevent code rearrangement */
volatile XLogCtlData *xlogctl = XLogCtl;
/*
* Is it safe to 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(trace_recovery(DEBUG2), "RM %d not safe to record restart point at %X/%X",
rmid,
checkPoint->redo.xlogid,
checkPoint->redo.xrecoff);
return;
}
}
/*
* Copy the checkpoint record to shared memory, so that bgwriter can use
* it the next time it wants to perform a restartpoint.
*/
SpinLockAcquire(&xlogctl->info_lck);
XLogCtl->lastCheckPointRecPtr = ReadRecPtr;
memcpy(&XLogCtl->lastCheckPoint, checkPoint, sizeof(CheckPoint));
SpinLockRelease(&xlogctl->info_lck);
}
/*
* Establish a restartpoint if possible.
*
* This is similar to CreateCheckPoint, but is used during WAL recovery
* to establish a point from which recovery can roll forward without
* replaying the entire recovery log.
*
* Returns true if a new restartpoint was established. We can only establish
* a restartpoint if we have replayed a safe checkpoint record since last
* restartpoint.
*/
bool
CreateRestartPoint(int flags)
{
XLogRecPtr lastCheckPointRecPtr;
CheckPoint lastCheckPoint;
/* use volatile pointer to prevent code rearrangement */
volatile XLogCtlData *xlogctl = XLogCtl;
/*
* Acquire CheckpointLock to ensure only one restartpoint or checkpoint
* happens at a time.
*/
LWLockAcquire(CheckpointLock, LW_EXCLUSIVE);
/* Get a local copy of the last safe checkpoint record. */
SpinLockAcquire(&xlogctl->info_lck);
lastCheckPointRecPtr = xlogctl->lastCheckPointRecPtr;
memcpy(&lastCheckPoint, &XLogCtl->lastCheckPoint, sizeof(CheckPoint));
SpinLockRelease(&xlogctl->info_lck);
/*
* Check that we're still in recovery mode. It's ok if we exit recovery
* mode after this check, the restart point is valid anyway.
*/
if (!RecoveryInProgress())
{
ereport(DEBUG2,
(errmsg("skipping restartpoint, recovery has already ended")));
LWLockRelease(CheckpointLock);
return false;
}
/*
* If the last checkpoint record we've replayed is already our last
* restartpoint, we can't perform a new restart point. We still update
* minRecoveryPoint in that case, so that if this is a shutdown restart
* point, we won't start up earlier than before. That's not strictly
* necessary, but when we get hot standby capability, it would be rather
* weird if the database opened up for read-only connections at a
* point-in-time before the last shutdown. Such time travel is still
* possible in case of immediate shutdown, though.
*
* We don't explicitly advance minRecoveryPoint when we do create a
* restartpoint. It's assumed that flushing the buffers will do that as a
* side-effect.
*/
if (XLogRecPtrIsInvalid(lastCheckPointRecPtr) ||
XLByteLE(lastCheckPoint.redo, ControlFile->checkPointCopy.redo))
{
XLogRecPtr InvalidXLogRecPtr = {0, 0};
ereport(DEBUG2,
(errmsg("skipping restartpoint, already performed at %X/%X",
lastCheckPoint.redo.xlogid, lastCheckPoint.redo.xrecoff)));
UpdateMinRecoveryPoint(InvalidXLogRecPtr, true);
LWLockRelease(CheckpointLock);
return false;
}
if (log_checkpoints)
{
/*
* Prepare to accumulate statistics.
*/
MemSet(&CheckpointStats, 0, sizeof(CheckpointStats));
CheckpointStats.ckpt_start_t = GetCurrentTimestamp();
LogCheckpointStart(flags, true);
}
CheckPointGuts(lastCheckPoint.redo, flags);
/*
* Update pg_control, using current time. Check that it still shows
* IN_ARCHIVE_RECOVERY state and an older checkpoint, else do nothing;
* this is a quick hack to make sure nothing really bad happens if
* somehow we get here after the end-of-recovery checkpoint.
*/
LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
if (ControlFile->state == DB_IN_ARCHIVE_RECOVERY &&
XLByteLT(ControlFile->checkPointCopy.redo, lastCheckPoint.redo))
{
ControlFile->prevCheckPoint = ControlFile->checkPoint;
ControlFile->checkPoint = lastCheckPointRecPtr;
ControlFile->checkPointCopy = lastCheckPoint;
ControlFile->time = (pg_time_t) time(NULL);
UpdateControlFile();
}
LWLockRelease(ControlFileLock);
/*
* Currently, there is no need to truncate pg_subtrans during recovery. If
* we did do that, we will need to have called StartupSUBTRANS() already
* and then TruncateSUBTRANS() would go here.
*/
/* All real work is done, but log before releasing lock. */
if (log_checkpoints)
LogCheckpointEnd(true);
ereport((log_checkpoints ? LOG : DEBUG2),
(errmsg("recovery restart point at %X/%X with latest known log time %s",
lastCheckPoint.redo.xlogid, lastCheckPoint.redo.xrecoff,
timestamptz_to_str(GetLatestXLogTime()))));
LWLockRelease(CheckpointLock);
return true;
}
/*
* 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
*
* Definitions of info values are in include/catalog/pg_control.h, though
* not all record types are related to control file updates.
*/
void
xlog_redo(XLogRecPtr lsn, XLogRecord *record)
{
uint8 info = record->xl_info & ~XLR_INFO_MASK;
/* Backup blocks are not used in xlog records */
Assert(!(record->xl_info & XLR_BKP_BLOCK_MASK));
if (info == XLOG_NEXTOID)
{
Oid nextOid;
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);
ShmemVariableCache->oldestXid = checkPoint.oldestXid;
ShmemVariableCache->oldestXidDB = checkPoint.oldestXidDB;
/* Check to see if any changes to max_connections give problems */
if (standbyState != STANDBY_DISABLED)
CheckRequiredParameterValues(checkPoint);
if (standbyState >= STANDBY_INITIALIZED)
{
/*
* Remove stale transactions, if any.
*/
ExpireOldKnownAssignedTransactionIds(checkPoint.nextXid);
StandbyReleaseOldLocks(checkPoint.nextXid);
}
/* 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);
if (TransactionIdPrecedes(ShmemVariableCache->oldestXid,
checkPoint.oldestXid))
{
ShmemVariableCache->oldestXid = checkPoint.oldestXid;
ShmemVariableCache->oldestXidDB = checkPoint.oldestXidDB;
}
/* 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; "
"oldest xid %u in DB %u; oldest running xid %u; %s",
checkpoint->redo.xlogid, checkpoint->redo.xrecoff,
checkpoint->ThisTimeLineID,
checkpoint->nextXidEpoch, checkpoint->nextXid,
checkpoint->nextOid,
checkpoint->nextMulti,
checkpoint->nextMultiOffset,
checkpoint->oldestXid,
checkpoint->oldestXidDB,
checkpoint->oldestActiveXid,
(info == XLOG_CHECKPOINT_SHUTDOWN) ? "shutdown" : "online");
}
else if (info == XLOG_NOOP)
{
appendStringInfo(buf, "xlog no-op");
}
else if (info == XLOG_NEXTOID)
{
Oid nextOid;
memcpy(&nextOid, rec, sizeof(Oid));
appendStringInfo(buf, "nextOid: %u", nextOid);
}
else if (info == XLOG_SWITCH)
{
appendStringInfo(buf, "xlog switch");
}
else
appendStringInfo(buf, "UNKNOWN");
}
#ifdef WAL_DEBUG
static void
xlog_outrec(StringInfo buf, XLogRecord *record)
{
int i;
appendStringInfo(buf, "prev %X/%X; xid %u",
record->xl_prev.xlogid, record->xl_prev.xrecoff,
record->xl_xid);
appendStringInfo(buf, "; len %u",
record->xl_len);
for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++)
{
if (record->xl_info & XLR_SET_BKP_BLOCK(i))
appendStringInfo(buf, "; bkpb%d", i + 1);
}
appendStringInfo(buf, ": %s", RmgrTable[record->xl_rmid].rm_name);
}
#endif /* WAL_DEBUG */
/*
* Return the (possible) sync flag used for opening a file, depending on the
* value of the GUC wal_sync_method.
*/
static int
get_sync_bit(int method)
{
/* If fsync is disabled, never open in sync mode */
if (!enableFsync)
return 0;
switch (method)
{
/*
* enum values for all sync options are defined even if they are
* not supported on the current platform. But if not, they are
* not included in the enum option array, and therefore will never
* be seen here.
*/
case SYNC_METHOD_FSYNC:
case SYNC_METHOD_FSYNC_WRITETHROUGH:
case SYNC_METHOD_FDATASYNC:
return 0;
#ifdef OPEN_SYNC_FLAG
case SYNC_METHOD_OPEN:
return OPEN_SYNC_FLAG;
#endif
#ifdef OPEN_DATASYNC_FLAG
case SYNC_METHOD_OPEN_DSYNC:
return OPEN_DATASYNC_FLAG;
#endif
default:
/* can't happen (unless we are out of sync with option array) */
elog(ERROR, "unrecognized wal_sync_method: %d", method);
return 0; /* silence warning */
}
}
/*
* GUC support
*/
bool
assign_xlog_sync_method(int new_sync_method, bool doit, GucSource source)
{
if (!doit)
return true;
if (sync_method != new_sync_method)
{
/*
* To ensure that no blocks escape unsynced, force an fsync on the
* currently open log segment (if any). Also, if the open flag is
* changing, close the log file so it will be reopened (with new flag
* bit) at next use.
*/
if (openLogFile >= 0)
{
if (pg_fsync(openLogFile) != 0)
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not fsync log file %u, segment %u: %m",
openLogId, openLogSeg)));
if (get_sync_bit(sync_method) != get_sync_bit(new_sync_method))
XLogFileClose();
}
}
return true;
}
/*
* 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:
case SYNC_METHOD_OPEN_DSYNC:
/* 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);
bool fast = PG_GETARG_BOOL(1);
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 (RecoveryInProgress())
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("recovery is in progress"),
errhint("WAL control functions cannot be executed during recovery.")));
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);
/*
* Force an XLOG file switch before the checkpoint, to ensure that the WAL
* segment the checkpoint is written to doesn't contain pages with old
* timeline IDs. That would otherwise happen if you called
* pg_start_backup() right after restoring from a PITR archive: the first
* WAL segment containing the startup checkpoint has pages in the
* beginning with the old timeline ID. That can cause trouble at recovery:
* we won't have a history file covering the old timeline if pg_xlog
* directory was not included in the base backup and the WAL archive was
* cleared too before starting the backup.
*/
RequestXLogSwitch();
/* 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 use CHECKPOINT_IMMEDIATE only if requested by user (via passing
* fast = true). Otherwise this can take awhile.
*/
RequestCheckpoint(CHECKPOINT_FORCE | CHECKPOINT_WAIT |
(fast ? CHECKPOINT_IMMEDIATE : 0));
/*
* Now we need to fetch the checkpoint record location, and also its
* REDO pointer. The oldest point in WAL that would be needed to
* restore starting from the checkpoint is precisely the REDO pointer.
*/
LWLockAcquire(ControlFileLock, LW_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];
char lastxlogfilename[MAXFNAMELEN];
char histfilename[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"))));
if (RecoveryInProgress())
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("recovery is in progress"),
errhint("WAL control functions cannot be executed during recovery.")));
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.")));
/*
* 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 both the last WAL file filled during backup and the history
* file have been archived. We assume that the alphabetic sorting
* property of the WAL files ensures any earlier WAL files are safely
* archived as well.
*
* We wait forever, since archive_command is supposed to work and we
* assume the admin wanted his backup to work completely. If you don't
* wish to wait, you can set statement_timeout.
*/
XLByteToPrevSeg(stoppoint, _logId, _logSeg);
XLogFileName(lastxlogfilename, ThisTimeLineID, _logId, _logSeg);
XLByteToSeg(startpoint, _logId, _logSeg);
BackupHistoryFileName(histfilename, ThisTimeLineID, _logId, _logSeg,
startpoint.xrecoff % XLogSegSize);
seconds_before_warning = 60;
waits = 0;
while (XLogArchiveIsBusy(lastxlogfilename) ||
XLogArchiveIsBusy(histfilename))
{
CHECK_FOR_INTERRUPTS();
pg_usleep(1000000L);
if (++waits >= seconds_before_warning)
{
seconds_before_warning *= 2; /* This wraps in >10 years... */
ereport(WARNING,
(errmsg("pg_stop_backup still waiting for archive to complete (%d seconds elapsed)",
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"))));
if (RecoveryInProgress())
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("recovery is in progress"),
errhint("WAL control functions cannot be executed during recovery.")));
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];
if (RecoveryInProgress())
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("recovery is in progress"),
errhint("WAL control functions cannot be executed during recovery.")));
/* 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];
if (RecoveryInProgress())
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("recovery is in progress"),
errhint("WAL control functions cannot be executed during recovery.")));
/*
* 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)));
}
}
/* ------------------------------------------------------
* Startup Process main entry point and signal handlers
* ------------------------------------------------------
*/
/*
* startupproc_quickdie() occurs when signalled SIGQUIT by the postmaster.
*
* Some backend has bought the farm,
* so we need to stop what we're doing and exit.
*/
static void
startupproc_quickdie(SIGNAL_ARGS)
{
PG_SETMASK(&BlockSig);
/*
* We DO NOT want to run proc_exit() callbacks -- we're here because
* shared memory may be corrupted, so we don't want to try to clean up our
* transaction. Just nail the windows shut and get out of town. Now that
* there's an atexit callback to prevent third-party code from breaking
* things by calling exit() directly, we have to reset the callbacks
* explicitly to make this work as intended.
*/
on_exit_reset();
/*
* Note we do exit(2) not exit(0). This is to force the postmaster into a
* system reset cycle if some idiot DBA sends a manual SIGQUIT to a random
* backend. This is necessary precisely because we don't clean up our
* shared memory state. (The "dead man switch" mechanism in pmsignal.c
* should ensure the postmaster sees this as a crash, too, but no harm in
* being doubly sure.)
*/
exit(2);
}
/* SIGHUP: set flag to re-read config file at next convenient time */
static void
StartupProcSigHupHandler(SIGNAL_ARGS)
{
got_SIGHUP = true;
}
/* SIGTERM: set flag to abort redo and exit */
static void
StartupProcShutdownHandler(SIGNAL_ARGS)
{
if (in_restore_command)
proc_exit(1);
else
shutdown_requested = true;
}
/* Main entry point for startup process */
void
StartupProcessMain(void)
{
/*
* If possible, make this process a group leader, so that the postmaster
* can signal any child processes too.
*/
#ifdef HAVE_SETSID
if (setsid() < 0)
elog(FATAL, "setsid() failed: %m");
#endif
/*
* Properly accept or ignore signals the postmaster might send us
*/
pqsignal(SIGHUP, StartupProcSigHupHandler); /* reload config file */
pqsignal(SIGINT, SIG_IGN); /* ignore query cancel */
pqsignal(SIGTERM, StartupProcShutdownHandler); /* request shutdown */
pqsignal(SIGQUIT, startupproc_quickdie); /* hard crash time */
pqsignal(SIGALRM, SIG_IGN);
pqsignal(SIGPIPE, SIG_IGN);
pqsignal(SIGUSR1, SIG_IGN);
pqsignal(SIGUSR2, SIG_IGN);
/*
* Reset some signals that are accepted by postmaster but not here
*/
pqsignal(SIGCHLD, SIG_DFL);
pqsignal(SIGTTIN, SIG_DFL);
pqsignal(SIGTTOU, SIG_DFL);
pqsignal(SIGCONT, SIG_DFL);
pqsignal(SIGWINCH, SIG_DFL);
/*
* Unblock signals (they were blocked when the postmaster forked us)
*/
PG_SETMASK(&UnBlockSig);
StartupXLOG();
/*
* Exit normally. Exit code 0 tells postmaster that we completed recovery
* successfully.
*/
proc_exit(0);
}
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