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xlog.c 99.38 KiB
/*-------------------------------------------------------------------------
*
* xlog.c
* PostgreSQL transaction log manager
*
*
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.115 2003/05/10 18:01:31 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <fcntl.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <dirent.h>
#include "access/clog.h"
#include "access/transam.h"
#include "access/xact.h"
#include "access/xlog.h"
#include "access/xlogutils.h"
#include "catalog/catversion.h"
#include "catalog/pg_control.h"
#include "storage/bufpage.h"
#include "storage/lwlock.h"
#include "storage/pmsignal.h"
#include "storage/proc.h"
#include "storage/sinval.h"
#include "storage/spin.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/relcache.h"
#include "miscadmin.h"
/*
* This chunk of hackery attempts to determine which file sync methods
* are available on the current platform, and to choose an appropriate
* default method. We assume that fsync() is always available, and that
* configure determined whether fdatasync() is.
*/
#define SYNC_METHOD_FSYNC 0
#define SYNC_METHOD_FDATASYNC 1
#define SYNC_METHOD_OPEN 2 /* used for both O_SYNC and
* O_DSYNC */
#if defined(O_SYNC)
#define OPEN_SYNC_FLAG O_SYNC
#else
#if defined(O_FSYNC)
#define OPEN_SYNC_FLAG O_FSYNC
#endif
#endif
#if defined(OPEN_SYNC_FLAG)
#if defined(O_DSYNC) && (O_DSYNC != OPEN_SYNC_FLAG)
#define OPEN_DATASYNC_FLAG O_DSYNC
#endif
#endif
#if defined(OPEN_DATASYNC_FLAG)
#define DEFAULT_SYNC_METHOD_STR "open_datasync"#define DEFAULT_SYNC_METHOD SYNC_METHOD_OPEN
#define DEFAULT_SYNC_FLAGBIT OPEN_DATASYNC_FLAG
#else
#if defined(HAVE_FDATASYNC)
#define DEFAULT_SYNC_METHOD_STR "fdatasync"
#define DEFAULT_SYNC_METHOD SYNC_METHOD_FDATASYNC
#define DEFAULT_SYNC_FLAGBIT 0
#else
#define DEFAULT_SYNC_METHOD_STR "fsync"
#define DEFAULT_SYNC_METHOD SYNC_METHOD_FSYNC
#define DEFAULT_SYNC_FLAGBIT 0
#endif
#endif
/* User-settable parameters */
int CheckPointSegments = 3;
int XLOGbuffers = 8;
int XLOG_DEBUG = 0;
char *XLOG_sync_method = NULL;
const char XLOG_sync_method_default[] = DEFAULT_SYNC_METHOD_STR;
char XLOG_archive_dir[MAXPGPATH]; /* null string means
* delete 'em */
/*
* XLOGfileslop is used in the code as the allowed "fuzz" in the number of
* preallocated XLOG segments --- we try to have at least XLOGfiles advance
* segments but no more than XLOGfileslop segments. This could
* be made a separate GUC variable, but at present I think it's sufficient
* to hardwire it as 2*CheckPointSegments+1. Under normal conditions, a
* checkpoint will free no more than 2*CheckPointSegments log segments, and
* we want to recycle all of them; the +1 allows boundary cases to happen
* without wasting a delete/create-segment cycle.
*/
#define XLOGfileslop (2*CheckPointSegments + 1)
/* these are derived from XLOG_sync_method by assign_xlog_sync_method */
static int sync_method = DEFAULT_SYNC_METHOD;
static int open_sync_bit = DEFAULT_SYNC_FLAGBIT;
#define XLOG_SYNC_BIT (enableFsync ? open_sync_bit : 0)
#define MinXLOGbuffers 4
/*
* ThisStartUpID will be same in all backends --- it identifies current
* instance of the database system.
*/
StartUpID ThisStartUpID = 0;
/* Are we doing recovery by reading XLOG? */
bool InRecovery = false;
/*
* MyLastRecPtr points to the start of the last XLOG record inserted by the
* current transaction. If MyLastRecPtr.xrecoff == 0, then the current
* xact hasn't yet inserted any transaction-controlled XLOG records.
*
* Note that XLOG records inserted outside transaction control are not
* reflected into MyLastRecPtr. They do, however, cause MyXactMadeXLogEntry
* to be set true. The latter can be used to test whether the current xact
* made any loggable changes (including out-of-xact changes, such as
* sequence updates).
*
* When we insert/update/delete a tuple in a temporary relation, we do not
* make any XLOG record, since we don't care about recovering the state of
* the temp rel after a crash. However, we will still need to remember * whether our transaction committed or aborted in that case. So, we must
* set MyXactMadeTempRelUpdate true to indicate that the XID will be of
* interest later.
*/
XLogRecPtr MyLastRecPtr = {0, 0};
bool MyXactMadeXLogEntry = false;
bool MyXactMadeTempRelUpdate = false;
/*
* ProcLastRecPtr points to the start of the last XLOG record inserted by the
* current backend. It is updated for all inserts, transaction-controlled
* or not. ProcLastRecEnd is similar but points to end+1 of last record.
*/
static XLogRecPtr ProcLastRecPtr = {0, 0};
XLogRecPtr ProcLastRecEnd = {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.
*/
static XLogRecPtr RedoRecPtr;
/*----------
* Shared-memory data structures for XLOG control
*
* LogwrtRqst indicates a byte position that we need to write and/or fsync
* the log up to (all records before that point must be written or fsynced).
* LogwrtResult indicates the byte positions we have already written/fsynced.
* These structs are identical but are declared separately to indicate their
* slightly different functions.
*
* We do a lot of pushups to minimize the amount of access to lockable
* shared memory values. There are actually three shared-memory copies of
* LogwrtResult, plus one unshared copy in each backend. Here's how it works:
* XLogCtl->LogwrtResult is protected by info_lck
* XLogCtl->Write.LogwrtResult is protected by WALWriteLock
* XLogCtl->Insert.LogwrtResult is protected by WALInsertLock
* One must hold the associated lock to read or write any of these, but
* of course no lock is needed to read/write the unshared LogwrtResult.
*
* XLogCtl->LogwrtResult and XLogCtl->Write.LogwrtResult are both "always
* right", since both are updated by a write or flush operation before
* it releases WALWriteLock. The point of keeping XLogCtl->Write.LogwrtResult
* is that it can be examined/modified by code that already holds WALWriteLock
* without needing to grab info_lck as well.
*
* XLogCtl->Insert.LogwrtResult may lag behind the reality of the other two,
* but is updated when convenient. Again, it exists for the convenience of
* code that is already holding WALInsertLock but not the other locks.
*
* The unshared LogwrtResult may lag behind any or all of these, and again
* is updated when convenient.
*
* The request bookkeeping is simpler: there is a shared XLogCtl->LogwrtRqst
* (protected by info_lck), but we don't need to cache any copies of it.
*
* Note that this all works because the request and result positions can only
* advance forward, never back up, and so we can easily determine which of two
* values is "more up to date".
*
* info_lck is only held long enough to read/update the protected variables,
* so it's a plain spinlock. The other locks are held longer (potentially * over I/O operations), so we use LWLocks for them. These locks are:
*
* WALInsertLock: must be held to insert a record into the WAL buffers.
*
* WALWriteLock: must be held to write WAL buffers to disk (XLogWrite or
* XLogFlush).
*
* ControlFileLock: must be held to read/update control file or create
* new log file.
*
* CheckpointLock: must be held to do a checkpoint (ensures only one
* checkpointer at a time; even though the postmaster won't launch
* parallel checkpoint processes, we need this because manual checkpoints
* could be launched simultaneously).
*
*----------
*/
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 */
uint16 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 */
} XLogCtlInsert;
/*
* Shared state data for XLogWrite/XLogFlush.
*/
typedef struct XLogCtlWrite
{
XLogwrtResult LogwrtResult; /* current value of LogwrtResult */
uint16 curridx; /* cache index of next block to write */
} XLogCtlWrite;
/*
* Total shared-memory state for XLOG.
*/
typedef struct XLogCtlData
{
/* Protected by WALInsertLock: */
XLogCtlInsert Insert;
/* Protected by info_lck: */
XLogwrtRqst LogwrtRqst;
XLogwrtResult LogwrtResult;
/* 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 + BLCKSZ */
uint32 XLogCacheByte; /* # bytes in xlog buffers */
uint32 XLogCacheBlck; /* highest allocated xlog buffer index */
StartUpID ThisStartUpID;
/* This value is not protected by *any* lock... */
/* see SetSavedRedoRecPtr/GetSavedRedoRecPtr */
XLogRecPtr SavedRedoRecPtr;
slock_t info_lck; /* locks shared LogwrtRqst/LogwrtResult */
} 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) \
(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) \
)
/* Increment an xlogid/segment pair */
#define NextLogSeg(logId, logSeg) \
do { \
if ((logSeg) >= XLogSegsPerFile-1) \
{ \
(logId)++; \
(logSeg) = 0; \
} \
else \
(logSeg)++; \
} while (0)
/* Decrement an xlogid/segment pair (assume it's not 0,0) */
#define PrevLogSeg(logId, logSeg) \
do { \
if (logSeg) \
(logSeg)--; \
else \
{ \
(logId)--; \
(logSeg) = XLogSegsPerFile-1; \
} \
} while (0)
/*
* Compute ID and segment from an XLogRecPtr.
*
* For XLByteToSeg, do the computation at face value. For XLByteToPrevSeg,
* a boundary byte is taken to be in the previous segment. This is suitable
* for deciding which segment to write given a pointer to a record end,
* for example. */
#define XLByteToSeg(xlrp, logId, logSeg) \
( logId = (xlrp).xlogid, \
logSeg = (xlrp).xrecoff / XLogSegSize \
)
#define XLByteToPrevSeg(xlrp, logId, logSeg) \
( logId = (xlrp).xlogid, \
logSeg = ((xlrp).xrecoff - 1) / XLogSegSize \
)
/*
* Is an XLogRecPtr within a particular XLOG segment?
*
* For XLByteInSeg, do the computation at face value. For XLByteInPrevSeg,
* a boundary byte is taken to be in the previous segment.
*/
#define XLByteInSeg(xlrp, logId, logSeg) \
((xlrp).xlogid == (logId) && \
(xlrp).xrecoff / XLogSegSize == (logSeg))
#define XLByteInPrevSeg(xlrp, logId, logSeg) \
((xlrp).xlogid == (logId) && \
((xlrp).xrecoff - 1) / XLogSegSize == (logSeg))
#define XLogFileName(path, log, seg) \
snprintf(path, MAXPGPATH, "%s/%08X%08X", \
XLogDir, log, seg)
#define PrevBufIdx(idx) \
(((idx) == 0) ? XLogCtl->XLogCacheBlck : ((idx) - 1))
#define NextBufIdx(idx) \
(((idx) == XLogCtl->XLogCacheBlck) ? 0 : ((idx) + 1))
#define XRecOffIsValid(xrecoff) \
((xrecoff) % BLCKSZ >= SizeOfXLogPHD && \
(BLCKSZ - (xrecoff) % BLCKSZ) >= SizeOfXLogRecord)
/*
* _INTL_MAXLOGRECSZ: max space needed for a record including header and
* any backup-block data.
*/
#define _INTL_MAXLOGRECSZ (SizeOfXLogRecord + MAXLOGRECSZ + \
XLR_MAX_BKP_BLOCKS * (sizeof(BkpBlock) + BLCKSZ))
/* File path names */
static char XLogDir[MAXPGPATH];
static char ControlFilePath[MAXPGPATH];
/*
* 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 (BLCKSZ bytes) */
static char *readBuf = NULL;
/* State information for XLOG reading */
static XLogRecPtr ReadRecPtr;
static XLogRecPtr EndRecPtr;
static XLogRecord *nextRecord = NULL;
static StartUpID lastReadSUI;
static bool InRedo = false;
static bool AdvanceXLInsertBuffer(void);
static void XLogWrite(XLogwrtRqst WriteRqst);
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, bool econt);
static void PreallocXlogFiles(XLogRecPtr endptr);
static void MoveOfflineLogs(uint32 log, uint32 seg, XLogRecPtr endptr);
static XLogRecord *ReadRecord(XLogRecPtr *RecPtr, int emode, char *buffer);
static bool ValidXLOGHeader(XLogPageHeader hdr, int emode, bool checkSUI);
static XLogRecord *ReadCheckpointRecord(XLogRecPtr RecPtr,
int whichChkpt,
char *buffer);
static void WriteControlFile(void);
static void ReadControlFile(void);
static char *str_time(time_t tnow);
static void xlog_outrec(char *buf, XLogRecord *record);
static void issue_xlog_fsync(void);
/*
* 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 list (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;
uint16 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_rdt[2 * XLR_MAX_BKP_BLOCKS];
crc64 rdata_crc;
uint32 len,
write_len;
unsigned i;
XLogwrtRqst LogwrtRqst;
bool updrqst;
bool no_tran = (rmid == RM_XLOG_ID) ? true : false;
if (info & XLR_INFO_MASK)
{
if ((info & XLR_INFO_MASK) != XLOG_NO_TRAN)
elog(PANIC, "XLogInsert: invalid info mask %02X",
(info & XLR_INFO_MASK));
no_tran = true;
info &= ~XLR_INFO_MASK;
}
/*
* 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 = SizeOfXLogPHD; /* start of 1st checkpoint record */
return (RecPtr);
}
/*
* Here we scan the rdata list, 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 yet since we don't know the final
* length or info bits quite yet.
*
* 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 list 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 list 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
* list later.
*/
begin:;
for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++)
{
dtbuf[i] = InvalidBuffer;
dtbuf_bkp[i] = false;
}
INIT_CRC64(rdata_crc);
len = 0;
for (rdt = rdata;;)
{
if (rdt->buffer == InvalidBuffer)
{
/* Simple data, just include it */
len += rdt->len;
COMP_CRC64(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 list item */
if (dtbuf_bkp[i])
rdt->data = NULL;
else if (rdt->data)
{
len += rdt->len;
COMP_CRC64(rdata_crc, rdt->data, rdt->len);
}
break;
}
if (dtbuf[i] == InvalidBuffer)
{
/* OK, put it in this slot */
dtbuf[i] = rdt->buffer;
/*
* XXX We assume page LSN is first data on page
*/
dtbuf_lsn[i] = *((XLogRecPtr *) BufferGetBlock(rdt->buffer));
if (XLByteLE(dtbuf_lsn[i], RedoRecPtr))
{
crc64 dtcrc;
dtbuf_bkp[i] = true;
rdt->data = NULL;
INIT_CRC64(dtcrc);
COMP_CRC64(dtcrc,
BufferGetBlock(dtbuf[i]),
BLCKSZ);
dtbuf_xlg[i].node = BufferGetFileNode(dtbuf[i]);
dtbuf_xlg[i].block = BufferGetBlockNumber(dtbuf[i]);
COMP_CRC64(dtcrc,
(char *) &(dtbuf_xlg[i]) + sizeof(crc64),
sizeof(BkpBlock) - sizeof(crc64));
FIN_CRC64(dtcrc);
dtbuf_xlg[i].crc = dtcrc;
}
else if (rdt->data)
{
len += rdt->len;
COMP_CRC64(rdata_crc, rdt->data, rdt->len);
}
break;
}
}
if (i >= XLR_MAX_BKP_BLOCKS)
elog(PANIC, "XLogInsert: can backup %d blocks at most",
XLR_MAX_BKP_BLOCKS);
}
/* Break out of loop when rdt points to last list item */
if (rdt->next == NULL)
break;
rdt = rdt->next;
}
/*
* NOTE: the test for len == 0 here is somewhat fishy, since in theory
* all of the rmgr data might have been suppressed in favor of backup
* blocks. Currently, all callers of XLogInsert provide at least some
* not-in-a-buffer data and so len == 0 should never happen, but that
* may not be true forever. If you need to remove the len == 0 check,
* also remove the check for xl_len == 0 in ReadRecord, below.
*/
if (len == 0 || len > MAXLOGRECSZ)
elog(PANIC, "XLogInsert: invalid record length %u", len);
START_CRIT_SECTION();
/* update LogwrtResult before doing cache fill check */
{
/* use volatile pointer to prevent code rearrangement */
volatile XLogCtlData *xlogctl = XLogCtl;
SpinLockAcquire_NoHoldoff(&xlogctl->info_lck);
LogwrtRqst = xlogctl->LogwrtRqst;
LogwrtResult = xlogctl->LogwrtResult;
SpinLockRelease_NoHoldoff(&xlogctl->info_lck);
}
/*
* If cache is half filled then try to acquire write lock and do
* XLogWrite. Ignore any fractional blocks in performing this check.
*/
LogwrtRqst.Write.xrecoff -= LogwrtRqst.Write.xrecoff % BLCKSZ;
if (LogwrtRqst.Write.xlogid != LogwrtResult.Write.xlogid ||
(LogwrtRqst.Write.xrecoff >= LogwrtResult.Write.xrecoff +
XLogCtl->XLogCacheByte / 2))
{
if (LWLockConditionalAcquire(WALWriteLock, LW_EXCLUSIVE))
{
LogwrtResult = XLogCtl->Write.LogwrtResult;
if (XLByteLT(LogwrtResult.Write, LogwrtRqst.Write))
XLogWrite(LogwrtRqst);
LWLockRelease(WALWriteLock);
}
}
/* 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 (!XLByteEQ(RedoRecPtr, Insert->RedoRecPtr))
{
Assert(XLByteLT(RedoRecPtr, Insert->RedoRecPtr));
RedoRecPtr = Insert->RedoRecPtr;
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;
}
}
}
/*
* Make additional rdata list 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 list. 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 list.
*/
write_len = len;
for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++)
{
if (dtbuf[i] == InvalidBuffer || !(dtbuf_bkp[i]))
continue;
info |= XLR_SET_BKP_BLOCK(i);
rdt->next = &(dtbuf_rdt[2 * i]);
dtbuf_rdt[2 * i].data = (char *) &(dtbuf_xlg[i]);
dtbuf_rdt[2 * i].len = sizeof(BkpBlock);
write_len += sizeof(BkpBlock);
rdt = dtbuf_rdt[2 * i].next = &(dtbuf_rdt[2 * i + 1]);
dtbuf_rdt[2 * i + 1].data = (char *) BufferGetBlock(dtbuf[i]);
dtbuf_rdt[2 * i + 1].len = BLCKSZ;
write_len += BLCKSZ;
dtbuf_rdt[2 * i + 1].next = NULL;
}
/* Insert record header */
updrqst = false;
freespace = INSERT_FREESPACE(Insert);
if (freespace < SizeOfXLogRecord)
{
updrqst = AdvanceXLInsertBuffer();
freespace = BLCKSZ - SizeOfXLogPHD;
}
curridx = Insert->curridx;
record = (XLogRecord *) Insert->currpos;
record->xl_prev = Insert->PrevRecord;
if (no_tran)
{
record->xl_xact_prev.xlogid = 0;
record->xl_xact_prev.xrecoff = 0;
}
else
record->xl_xact_prev = MyLastRecPtr;
record->xl_xid = GetCurrentTransactionId();
record->xl_len = len; /* doesn't include backup blocks */
record->xl_info = info;
record->xl_rmid = rmid;
/* Now we can finish computing the main CRC */
COMP_CRC64(rdata_crc, (char *) record + sizeof(crc64),
SizeOfXLogRecord - sizeof(crc64));
FIN_CRC64(rdata_crc);
record->xl_crc = rdata_crc;
/* Compute record's XLOG location */
INSERT_RECPTR(RecPtr, Insert, curridx);
/* If first XLOG record of transaction, save it in PGPROC array */
if (MyLastRecPtr.xrecoff == 0 && !no_tran)
{
/*
* We do not acquire SInvalLock here because of possible deadlock.
* Anyone who wants to inspect other procs' logRec must acquire
* WALInsertLock, instead. A better solution would be a per-PROC
* spinlock, but no time for that before 7.2 --- tgl 12/19/01. */
MyProc->logRec = RecPtr;
}
if (XLOG_DEBUG)
{
char buf[8192];
sprintf(buf, "INSERT @ %X/%X: ", RecPtr.xlogid, RecPtr.xrecoff);
xlog_outrec(buf, record);
if (rdata->data != NULL)
{
strcat(buf, " - ");
RmgrTable[record->xl_rmid].rm_desc(buf, record->xl_info, rdata->data);
}
elog(LOG, "%s", buf);
}
/* Record begin of record in appropriate places */
if (!no_tran)
MyLastRecPtr = RecPtr;
ProcLastRecPtr = RecPtr;
Insert->PrevRecord = RecPtr;
MyXactMadeXLogEntry = true;
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();
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 = BLCKSZ - SizeOfXLogPHD - SizeOfXLogContRecord;
}
/* 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);
/* Need to update shared LogwrtRqst if some block was filled up */
if (freespace < SizeOfXLogRecord)
updrqst = true; /* curridx is filled and available for
* writing out */
else
curridx = PrevBufIdx(curridx);
WriteRqst = XLogCtl->xlblocks[curridx];
LWLockRelease(WALInsertLock);
if (updrqst)
{
/* use volatile pointer to prevent code rearrangement */
volatile XLogCtlData *xlogctl = XLogCtl;
SpinLockAcquire_NoHoldoff(&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_NoHoldoff(&xlogctl->info_lck);
}
ProcLastRecEnd = RecPtr;
END_CRIT_SECTION();
return (RecPtr);
}
/*
* Advance the Insert state to the next buffer page, writing out the next
* buffer if it still contains unwritten data.
*
* 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(void)
{
XLogCtlInsert *Insert = &XLogCtl->Insert;
XLogCtlWrite *Write = &XLogCtl->Write;
uint16 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_NoHoldoff(&xlogctl->info_lck);
if (XLByteLT(xlogctl->LogwrtRqst.Write, FinishedPageRqstPtr))
xlogctl->LogwrtRqst.Write = FinishedPageRqstPtr;
LogwrtResult = xlogctl->LogwrtResult;
SpinLockRelease_NoHoldoff(&xlogctl->info_lck);
}
update_needed = false; /* Did the shared-request update */
if (XLByteLE(OldPageRqstPtr, LogwrtResult.Write))
{
/* OK, someone wrote it already */
Insert->LogwrtResult = LogwrtResult;
}
else
{
/* Must acquire write lock */
LWLockAcquire(WALWriteLock, LW_EXCLUSIVE);
LogwrtResult = Write->LogwrtResult;
if (XLByteLE(OldPageRqstPtr, LogwrtResult.Write))
{
/* OK, someone wrote it already */
LWLockRelease(WALWriteLock);
Insert->LogwrtResult = LogwrtResult;
}
else
{
/*
* Have to write buffers while holding insert lock. This
* is not good, so only write as much as we absolutely
* must.
*/
WriteRqst.Write = OldPageRqstPtr;
WriteRqst.Flush.xlogid = 0;
WriteRqst.Flush.xrecoff = 0;
XLogWrite(WriteRqst);
LWLockRelease(WALWriteLock);
Insert->LogwrtResult = LogwrtResult;
}
}
}
/*
* Now the next buffer slot is free and we can set it up to be the
* next output page.
*/
NewPageEndPtr = XLogCtl->xlblocks[Insert->curridx];
if (NewPageEndPtr.xrecoff >= XLogFileSize)
{
/* crossing a logid boundary */
NewPageEndPtr.xlogid += 1;
NewPageEndPtr.xrecoff = BLCKSZ;
}
else
NewPageEndPtr.xrecoff += BLCKSZ;
XLogCtl->xlblocks[nextidx] = NewPageEndPtr; NewPage = (XLogPageHeader) (XLogCtl->pages + nextidx * BLCKSZ);
Insert->curridx = nextidx;
Insert->currpage = NewPage;
Insert->currpos = ((char *) NewPage) + SizeOfXLogPHD;
/*
* 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, BLCKSZ);
/* And fill the new page's header */
NewPage->xlp_magic = XLOG_PAGE_MAGIC;
/* NewPage->xlp_info = 0; */ /* done by memset */
NewPage->xlp_sui = ThisStartUpID;
NewPage->xlp_pageaddr.xlogid = NewPageEndPtr.xlogid;
NewPage->xlp_pageaddr.xrecoff = NewPageEndPtr.xrecoff - BLCKSZ;
return update_needed;
}
/*
* Write and/or fsync the log at least as far as WriteRqst indicates.
*
* Must be called with WALWriteLock held.
*/
static void
XLogWrite(XLogwrtRqst WriteRqst)
{
XLogCtlWrite *Write = &XLogCtl->Write;
char *from;
bool ispartialpage;
bool use_existent;
/*
* Update local LogwrtResult (caller probably did this already,
* but...)
*/
LogwrtResult = Write->LogwrtResult;
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[Write->curridx]))
elog(PANIC, "XLogWrite: write request %X/%X is past end of log %X/%X",
LogwrtResult.Write.xlogid, LogwrtResult.Write.xrecoff,
XLogCtl->xlblocks[Write->curridx].xlogid,
XLogCtl->xlblocks[Write->curridx].xrecoff);
/* Advance LogwrtResult.Write to end of current buffer page */
LogwrtResult.Write = XLogCtl->xlblocks[Write->curridx];
ispartialpage = XLByteLT(WriteRqst.Write, LogwrtResult.Write);
if (!XLByteInPrevSeg(LogwrtResult.Write, openLogId, openLogSeg))
{
/*
* Switch to new logfile segment.
*/
if (openLogFile >= 0)
{
if (close(openLogFile) != 0)
elog(PANIC, "close of log file %u, segment %u failed: %m",
openLogId, openLogSeg);
openLogFile = -1;
} XLByteToPrevSeg(LogwrtResult.Write, openLogId, openLogSeg);
/* create/use new log file */
use_existent = true;
openLogFile = XLogFileInit(openLogId, openLogSeg,
&use_existent, true);
openLogOff = 0;
/* update pg_control, unless someone else already did */
LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
if (ControlFile->logId < openLogId ||
(ControlFile->logId == openLogId &&
ControlFile->logSeg < openLogSeg + 1))
{
ControlFile->logId = openLogId;
ControlFile->logSeg = openLogSeg + 1;
ControlFile->time = time(NULL);
UpdateControlFile();
/*
* Signal postmaster to start a checkpoint if it's been
* too long since the last one. (We look at local copy of
* RedoRecPtr which might be a little out of date, but
* should be close enough for this purpose.)
*/
if (IsUnderPostmaster &&
(openLogId != RedoRecPtr.xlogid ||
openLogSeg >= (RedoRecPtr.xrecoff / XLogSegSize) +
(uint32) CheckPointSegments))
{
if (XLOG_DEBUG)
elog(LOG, "XLogWrite: time for a checkpoint, signaling postmaster");
SendPostmasterSignal(PMSIGNAL_DO_CHECKPOINT);
}
}
LWLockRelease(ControlFileLock);
}
if (openLogFile < 0)
{
XLByteToPrevSeg(LogwrtResult.Write, openLogId, openLogSeg);
openLogFile = XLogFileOpen(openLogId, openLogSeg, false);
openLogOff = 0;
}
/* Need to seek in the file? */
if (openLogOff != (LogwrtResult.Write.xrecoff - BLCKSZ) % XLogSegSize)
{
openLogOff = (LogwrtResult.Write.xrecoff - BLCKSZ) % XLogSegSize;
if (lseek(openLogFile, (off_t) openLogOff, SEEK_SET) < 0)
elog(PANIC, "lseek of log file %u, segment %u, offset %u failed: %m",
openLogId, openLogSeg, openLogOff);
}
/* OK to write the page */
from = XLogCtl->pages + Write->curridx * BLCKSZ;
errno = 0;
if (write(openLogFile, from, BLCKSZ) != BLCKSZ)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
elog(PANIC, "write of log file %u, segment %u, offset %u failed: %m",
openLogId, openLogSeg, openLogOff);
}
openLogOff += BLCKSZ;
/*
* 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.
*/
if (openLogOff >= XLogSegSize && !ispartialpage)
{
issue_xlog_fsync();
LogwrtResult.Flush = LogwrtResult.Write; /* end of current page */
}
if (ispartialpage)
{
/* Only asked to write a partial page */
LogwrtResult.Write = WriteRqst.Write;
break;
}
Write->curridx = NextBufIdx(Write->curridx);
}
/*
* If asked to flush, do so
*/
if (XLByteLT(LogwrtResult.Flush, WriteRqst.Flush) &&
XLByteLT(LogwrtResult.Flush, LogwrtResult.Write))
{
/*
* Could get here without iterating above loop, in which case we
* might have no open file or the wrong one. However, we do not
* need to fsync more than one file.
*/
if (sync_method != SYNC_METHOD_OPEN)
{
if (openLogFile >= 0 &&
!XLByteInPrevSeg(LogwrtResult.Write, openLogId, openLogSeg))
{
if (close(openLogFile) != 0)
elog(PANIC, "close of log file %u, segment %u failed: %m",
openLogId, openLogSeg);
openLogFile = -1;
}
if (openLogFile < 0)
{
XLByteToPrevSeg(LogwrtResult.Write, openLogId, openLogSeg);
openLogFile = XLogFileOpen(openLogId, openLogSeg, false);
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_NoHoldoff(&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_NoHoldoff(&xlogctl->info_lck);
}
Write->LogwrtResult = LogwrtResult;
}
/*
* Ensure that all XLOG data through the given position is flushed to disk.
*
* NOTE: this differs from XLogWrite mainly in that the WALWriteLock is not
* already held, and we try to avoid acquiring it if possible.
*/
void
XLogFlush(XLogRecPtr record)
{
XLogRecPtr WriteRqstPtr;
XLogwrtRqst WriteRqst;
/* Disabled during REDO */
if (InRedo)
return;
/* Quick exit if already known flushed */
if (XLByteLE(record, LogwrtResult.Flush))
return;
if (XLOG_DEBUG)
{
elog(LOG, "XLogFlush%s: request %X/%X; write %X/%X; flush %X/%X",
(IsBootstrapProcessingMode()) ? "(bootstrap)" : "",
record.xlogid, record.xrecoff,
LogwrtResult.Write.xlogid, LogwrtResult.Write.xrecoff,
LogwrtResult.Flush.xlogid, LogwrtResult.Flush.xrecoff);
}
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_NoHoldoff(&xlogctl->info_lck);
if (XLByteLT(WriteRqstPtr, xlogctl->LogwrtRqst.Write))
WriteRqstPtr = xlogctl->LogwrtRqst.Write;
LogwrtResult = xlogctl->LogwrtResult;
SpinLockRelease_NoHoldoff(&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);
}
LWLockRelease(WALWriteLock);
}
END_CRIT_SECTION();
/*
* If we still haven't flushed to the request point then we have a
* problem; most likely, the requested flush point is past end of
* XLOG. This has been seen to occur when a disk page has a corrupted
* LSN.
*
* Formerly we treated this as a PANIC condition, but that hurts the
* system's robustness rather than helping it: we do not want to take
* down the whole system due to corruption on one data page. In
* particular, if the bad page is encountered again during recovery
* then we would be unable to restart the database at all! (This
* scenario has actually happened in the field several times with 7.1
* releases. Note that we cannot get here while InRedo is true, but if
* the bad page is brought in and marked dirty during recovery then
* CreateCheckpoint will try to flush it at the end of recovery.)
*
* The current approach is to ERROR under normal conditions, but only
* WARNING during recovery, so that the system can be brought up even
* if there's a corrupt LSN. Note that for calls from xact.c, the
* ERROR will be promoted to PANIC since xact.c calls this routine
* inside a critical section. However, calls from bufmgr.c are not
* within critical sections and so we will not force a restart for a
* bad LSN on a data page.
*/
if (XLByteLT(LogwrtResult.Flush, record))
elog(InRecovery ? WARNING : ERROR,
"XLogFlush: request %X/%X is not satisfied --- flushed only to %X/%X",
record.xlogid, record.xrecoff,
LogwrtResult.Flush.xlogid, LogwrtResult.Flush.xrecoff);
}
/*
* 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.
*/
static int
XLogFileInit(uint32 log, uint32 seg,
bool *use_existent, bool use_lock)
{
char path[MAXPGPATH];
char tmppath[MAXPGPATH];
char zbuffer[BLCKSZ];
int fd;
int nbytes;
XLogFileName(path, log, seg);
/*
* Try to use existent file (checkpoint maker may have created it
* already)
*/
if (*use_existent)
{
fd = BasicOpenFile(path, O_RDWR | PG_BINARY | XLOG_SYNC_BIT,
S_IRUSR | S_IWUSR);
if (fd < 0)
{
if (errno != ENOENT)
elog(PANIC, "open of %s (log file %u, segment %u) failed: %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.
*/
snprintf(tmppath, MAXPGPATH, "%s/xlogtemp.%d",
XLogDir, (int) getpid());
unlink(tmppath);
/* do not use XLOG_SYNC_BIT here --- want to fsync only at end of fill */
fd = BasicOpenFile(tmppath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
S_IRUSR | S_IWUSR);
if (fd < 0)
elog(PANIC, "creation of file %s failed: %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.
*/
MemSet(zbuffer, 0, sizeof(zbuffer));
for (nbytes = 0; nbytes < XLogSegSize; nbytes += sizeof(zbuffer))
{
errno = 0;
if ((int) write(fd, zbuffer, sizeof(zbuffer)) != (int) sizeof(zbuffer))
{
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;
elog(PANIC, "ZeroFill failed to write %s: %m", tmppath);
}
}
if (pg_fsync(fd) != 0)
elog(PANIC, "fsync of file %s failed: %m", tmppath);
close(fd);
/*
* 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.
*/
if (!InstallXLogFileSegment(log, seg, tmppath,
*use_existent, XLOGfileslop,
use_lock))
{
/* No need for any more future segments... */
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 | XLOG_SYNC_BIT,
S_IRUSR | S_IWUSR);
if (fd < 0)
elog(PANIC, "open of %s (log file %u, segment %u) failed: %m",
path, log, seg);
return (fd);
}
/*
* 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).
*
* 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. (Irrelevant if
* find_free is FALSE.)
*
* use_lock: if TRUE, acquire ControlFileLock while moving file into
* place. This should be TRUE except during bootstrap log creation. The
* caller must *not* hold the lock at call.
*
* Returns TRUE if file installed, FALSE if not installed because of
* exceeding max_advance limit. (Any other kind of failure causes elog().)
*/
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;
XLogFileName(path, 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);
XLogFileName(path, 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)
elog(PANIC, "link from %s to %s (initialization of log file %u, segment %u) failed: %m",
tmppath, path, log, seg);
unlink(tmppath);
#else
if (rename(tmppath, path) < 0)
elog(PANIC, "rename from %s to %s (initialization of log file %u, segment %u) failed: %m",
tmppath, path, log, seg);
#endif
if (use_lock)
LWLockRelease(ControlFileLock);
return true;
}
/*
* Open a pre-existing logfile segment.
*/
static int
XLogFileOpen(uint32 log, uint32 seg, bool econt)
{
char path[MAXPGPATH];
int fd;
XLogFileName(path, log, seg);
fd = BasicOpenFile(path, O_RDWR | PG_BINARY | XLOG_SYNC_BIT,
S_IRUSR | S_IWUSR); if (fd < 0)
{
if (econt && errno == ENOENT)
{
elog(LOG, "open of %s (log file %u, segment %u) failed: %m",
path, log, seg);
return (fd);
}
elog(PANIC, "open of %s (log file %u, segment %u) failed: %m",
path, log, seg);
}
return (fd);
}
/*
* Preallocate log files beyond the specified log endpoint, according to
* the XLOGfile user parameter.
*/
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);
}
}
/*
* Remove or move offline 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
MoveOfflineLogs(uint32 log, uint32 seg, XLogRecPtr endptr)
{
uint32 endlogId;
uint32 endlogSeg;
DIR *xldir;
struct dirent *xlde;
char lastoff[32];
char path[MAXPGPATH];
XLByteToPrevSeg(endptr, endlogId, endlogSeg);
xldir = opendir(XLogDir);
if (xldir == NULL)
elog(PANIC, "could not open transaction log directory (%s): %m",
XLogDir);
sprintf(lastoff, "%08X%08X", log, seg);
errno = 0;
while ((xlde = readdir(xldir)) != NULL)
{
if (strlen(xlde->d_name) == 16 &&
strspn(xlde->d_name, "0123456789ABCDEF") == 16 &&
strcmp(xlde->d_name, lastoff) <= 0)
{ snprintf(path, MAXPGPATH, "%s/%s", XLogDir, xlde->d_name);
if (XLOG_archive_dir[0])
{
elog(LOG, "archiving transaction log file %s",
xlde->d_name);
elog(WARNING, "archiving log files is not implemented!");
}
else
{
/*
* Before deleting the file, see if it can be recycled as
* a future log segment. We allow recycling segments up
* to XLOGfileslop segments beyond the current XLOG
* location.
*/
if (InstallXLogFileSegment(endlogId, endlogSeg, path,
true, XLOGfileslop,
true))
{
elog(LOG, "recycled transaction log file %s",
xlde->d_name);
}
else
{
/* No need for any more future segments... */
elog(LOG, "removing transaction log file %s",
xlde->d_name);
unlink(path);
}
}
}
errno = 0;
}
if (errno)
elog(PANIC, "could not read transaction log directory (%s): %m",
XLogDir);
closedir(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.
*/
static void
RestoreBkpBlocks(XLogRecord *record, XLogRecPtr lsn)
{
Relation reln;
Buffer buffer;
Page page;
BkpBlock bkpb;
char *blk;
int i;
blk = (char *) XLogRecGetData(record) + record->xl_len;
for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++)
{
if (!(record->xl_info & XLR_SET_BKP_BLOCK(i)))
continue;
memcpy((char *) &bkpb, blk, sizeof(BkpBlock));
blk += sizeof(BkpBlock);
reln = XLogOpenRelation(true, record->xl_rmid, bkpb.node);
if (reln)
{
buffer = XLogReadBuffer(true, reln, bkpb.block);
if (BufferIsValid(buffer))
{ page = (Page) BufferGetPage(buffer);
memcpy((char *) page, blk, BLCKSZ);
PageSetLSN(page, lsn);
PageSetSUI(page, ThisStartUpID);
UnlockAndWriteBuffer(buffer);
}
}
blk += BLCKSZ;
}
}
/*
* 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)
{
crc64 crc;
crc64 cbuf;
int i;
uint32 len = record->xl_len;
char *blk;
/* Check CRC of rmgr data and record header */
INIT_CRC64(crc);
COMP_CRC64(crc, XLogRecGetData(record), len);
COMP_CRC64(crc, (char *) record + sizeof(crc64),
SizeOfXLogRecord - sizeof(crc64));
FIN_CRC64(crc);
if (!EQ_CRC64(record->xl_crc, crc))
{
elog(emode, "ReadRecord: bad resource manager data checksum in record at %X/%X",
recptr.xlogid, recptr.xrecoff);
return (false);
}
/* Check CRCs of backup blocks, if any */
blk = (char *) XLogRecGetData(record) + len;
for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++)
{
if (!(record->xl_info & XLR_SET_BKP_BLOCK(i)))
continue;
INIT_CRC64(crc);
COMP_CRC64(crc, blk + sizeof(BkpBlock), BLCKSZ);
COMP_CRC64(crc, blk + sizeof(crc64),
sizeof(BkpBlock) - sizeof(crc64));
FIN_CRC64(crc);
memcpy((char *) &cbuf, blk, sizeof(crc64)); /* don't assume
* alignment */
if (!EQ_CRC64(cbuf, crc))
{
elog(emode, "ReadRecord: bad checksum of backup block %d in record at %X/%X",
i + 1, recptr.xlogid, recptr.xrecoff);
return (false);
}
blk += sizeof(BkpBlock) + BLCKSZ;
}
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.)
*
* buffer is a workspace at least _INTL_MAXLOGRECSZ bytes long. It is needed
* to reassemble a record that crosses block boundaries. Note that on
* successful return, the returned record pointer always points at buffer.
*/
static XLogRecord *
ReadRecord(XLogRecPtr *RecPtr, int emode, char *buffer)
{
XLogRecord *record;
XLogRecPtr tmpRecPtr = EndRecPtr;
uint32 len,
total_len;
uint32 targetPageOff;
unsigned i;
bool nextmode = false;
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(BLCKSZ);
Assert(readBuf != NULL);
}
if (RecPtr == NULL)
{
RecPtr = &tmpRecPtr;
nextmode = true;
/* 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 % BLCKSZ != 0)
tmpRecPtr.xrecoff += (BLCKSZ - tmpRecPtr.xrecoff % BLCKSZ);
if (tmpRecPtr.xrecoff >= XLogFileSize)
{
(tmpRecPtr.xlogid)++;
tmpRecPtr.xrecoff = 0;
}
tmpRecPtr.xrecoff += SizeOfXLogPHD;
}
else if (!XRecOffIsValid(RecPtr->xrecoff))
elog(PANIC, "ReadRecord: invalid record offset at %X/%X",
RecPtr->xlogid, RecPtr->xrecoff);
if (readFile >= 0 && !XLByteInSeg(*RecPtr, readId, readSeg))
{
close(readFile);
readFile = -1;
}
XLByteToSeg(*RecPtr, readId, readSeg);
if (readFile < 0)
{
readFile = XLogFileOpen(readId, readSeg, (emode == LOG)); if (readFile < 0)
goto next_record_is_invalid;
readOff = (uint32) (-1); /* force read to occur below */
}
targetPageOff = ((RecPtr->xrecoff % XLogSegSize) / BLCKSZ) * BLCKSZ;
if (readOff != targetPageOff)
{
readOff = targetPageOff;
if (lseek(readFile, (off_t) readOff, SEEK_SET) < 0)
{
elog(emode, "ReadRecord: lseek of log file %u, segment %u, offset %u failed: %m",
readId, readSeg, readOff);
goto next_record_is_invalid;
}
if (read(readFile, readBuf, BLCKSZ) != BLCKSZ)
{
elog(emode, "ReadRecord: read of log file %u, segment %u, offset %u failed: %m",
readId, readSeg, readOff);
goto next_record_is_invalid;
}
if (!ValidXLOGHeader((XLogPageHeader) readBuf, emode, nextmode))
goto next_record_is_invalid;
}
if ((((XLogPageHeader) readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD) &&
RecPtr->xrecoff % BLCKSZ == SizeOfXLogPHD)
{
elog(emode, "ReadRecord: contrecord is requested by %X/%X",
RecPtr->xlogid, RecPtr->xrecoff);
goto next_record_is_invalid;
}
record = (XLogRecord *) ((char *) readBuf + RecPtr->xrecoff % BLCKSZ);
got_record:;
/*
* Currently, xl_len == 0 must be bad data, but that might not be true
* forever. See note in XLogInsert.
*/
if (record->xl_len == 0)
{
elog(emode, "ReadRecord: record with zero length at %X/%X",
RecPtr->xlogid, RecPtr->xrecoff);
goto next_record_is_invalid;
}
/*
* Compute total length of record including any appended backup
* blocks.
*/
total_len = SizeOfXLogRecord + record->xl_len;
for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++)
{
if (!(record->xl_info & XLR_SET_BKP_BLOCK(i)))
continue;
total_len += sizeof(BkpBlock) + BLCKSZ;
}
/*
* Make sure it will fit in buffer (currently, it is mechanically
* impossible for this test to fail, but it seems like a good idea
* anyway).
*/
if (total_len > _INTL_MAXLOGRECSZ)
{
elog(emode, "ReadRecord: record length %u at %X/%X too long",
total_len, RecPtr->xlogid, RecPtr->xrecoff);
goto next_record_is_invalid;
}
if (record->xl_rmid > RM_MAX_ID) {
elog(emode, "ReadRecord: invalid resource manager id %u at %X/%X",
record->xl_rmid, RecPtr->xlogid, RecPtr->xrecoff);
goto next_record_is_invalid;
}
nextRecord = NULL;
len = BLCKSZ - RecPtr->xrecoff % 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 += BLCKSZ;
if (readOff >= XLogSegSize)
{
close(readFile);
readFile = -1;
NextLogSeg(readId, readSeg);
readFile = XLogFileOpen(readId, readSeg, (emode == LOG));
if (readFile < 0)
goto next_record_is_invalid;
readOff = 0;
}
if (read(readFile, readBuf, BLCKSZ) != BLCKSZ)
{
elog(emode, "ReadRecord: read of log file %u, segment %u, offset %u failed: %m",
readId, readSeg, readOff);
goto next_record_is_invalid;
}
if (!ValidXLOGHeader((XLogPageHeader) readBuf, emode, true))
goto next_record_is_invalid;
if (!(((XLogPageHeader) readBuf)->xlp_info & XLP_FIRST_IS_CONTRECORD))
{
elog(emode, "ReadRecord: there is no ContRecord flag in log file %u, segment %u, offset %u",
readId, readSeg, readOff);
goto next_record_is_invalid;
}
contrecord = (XLogContRecord *) ((char *) readBuf + SizeOfXLogPHD);
if (contrecord->xl_rem_len == 0 ||
total_len != (contrecord->xl_rem_len + gotlen))
{
elog(emode, "ReadRecord: 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 = BLCKSZ - SizeOfXLogPHD - 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;
if (BLCKSZ - SizeOfXLogRecord >= SizeOfXLogPHD +
SizeOfXLogContRecord + MAXALIGN(contrecord->xl_rem_len))
{
nextRecord = (XLogRecord *) ((char *) contrecord +
SizeOfXLogContRecord + MAXALIGN(contrecord->xl_rem_len)); }
EndRecPtr.xlogid = readId;
EndRecPtr.xrecoff = readSeg * XLogSegSize + readOff +
SizeOfXLogPHD + SizeOfXLogContRecord +
MAXALIGN(contrecord->xl_rem_len);
ReadRecPtr = *RecPtr;
return record;
}
/* Record does not cross a page boundary */
if (!RecordIsValid(record, *RecPtr, emode))
goto next_record_is_invalid;
if (BLCKSZ - SizeOfXLogRecord >= RecPtr->xrecoff % 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);
return (XLogRecord *) buffer;
next_record_is_invalid:;
close(readFile);
readFile = -1;
nextRecord = NULL;
return NULL;
}
/*
* Check whether the xlog header of a page just read in looks valid.
*
* This is just a convenience subroutine to avoid duplicated code in
* ReadRecord. It's not intended for use from anywhere else.
*/
static bool
ValidXLOGHeader(XLogPageHeader hdr, int emode, bool checkSUI)
{
XLogRecPtr recaddr;
if (hdr->xlp_magic != XLOG_PAGE_MAGIC)
{
elog(emode, "ReadRecord: 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)
{
elog(emode, "ReadRecord: 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))
{
elog(emode, "ReadRecord: 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;
}
/*
* We disbelieve a SUI less than the previous page's SUI, or more than
* a few counts greater. In theory as many as 512 shutdown checkpoint
* records could appear on a 32K-sized xlog page, so that's the most
* differential there could legitimately be.
*
* Note this check can only be applied when we are reading the next page
* in sequence, so ReadRecord passes a flag indicating whether to
* check. */
if (checkSUI)
{
if (hdr->xlp_sui < lastReadSUI ||
hdr->xlp_sui > lastReadSUI + 512)
{
/* translator: SUI = startup id */
elog(emode, "ReadRecord: out-of-sequence SUI %u (after %u) in log file %u, segment %u, offset %u",
hdr->xlp_sui, lastReadSUI, readId, readSeg, readOff);
return false;
}
}
lastReadSUI = hdr->xlp_sui;
return true;
}
/*
* 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.
*/
void
XLOGPathInit(void)
{
/* Init XLOG file paths */
snprintf(XLogDir, MAXPGPATH, "%s/pg_xlog", DataDir);
snprintf(ControlFilePath, MAXPGPATH, "%s/global/pg_control", DataDir);
}
static void
WriteControlFile(void)
{
int fd;
char buffer[BLCKSZ]; /* need not be aligned */
char *localeptr;
/*
* Initialize version and compatibility-check fields
*/
ControlFile->pg_control_version = PG_CONTROL_VERSION;
ControlFile->catalog_version_no = CATALOG_VERSION_NO;
ControlFile->blcksz = BLCKSZ;
ControlFile->relseg_size = RELSEG_SIZE;
ControlFile->nameDataLen = NAMEDATALEN;
ControlFile->funcMaxArgs = FUNC_MAX_ARGS;
#ifdef HAVE_INT64_TIMESTAMP
ControlFile->enableIntTimes = TRUE;
#else
ControlFile->enableIntTimes = FALSE;
#endif
ControlFile->localeBuflen = LOCALE_NAME_BUFLEN;
localeptr = setlocale(LC_COLLATE, NULL);
if (!localeptr)
elog(PANIC, "invalid LC_COLLATE setting");
StrNCpy(ControlFile->lc_collate, localeptr, LOCALE_NAME_BUFLEN);
localeptr = setlocale(LC_CTYPE, NULL);
if (!localeptr) elog(PANIC, "invalid LC_CTYPE setting");
StrNCpy(ControlFile->lc_ctype, localeptr, LOCALE_NAME_BUFLEN);
/* Contents are protected with a CRC */
INIT_CRC64(ControlFile->crc);
COMP_CRC64(ControlFile->crc,
(char *) ControlFile + sizeof(crc64),
sizeof(ControlFileData) - sizeof(crc64));
FIN_CRC64(ControlFile->crc);
/*
* We write out BLCKSZ 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) > BLCKSZ)
elog(PANIC, "sizeof(ControlFileData) is larger than BLCKSZ; fix either one");
memset(buffer, 0, BLCKSZ);
memcpy(buffer, ControlFile, sizeof(ControlFileData));
fd = BasicOpenFile(ControlFilePath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
S_IRUSR | S_IWUSR);
if (fd < 0)
elog(PANIC, "WriteControlFile: could not create control file (%s): %m",
ControlFilePath);
errno = 0;
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
elog(PANIC, "WriteControlFile: write to control file failed: %m");
}
if (pg_fsync(fd) != 0)
elog(PANIC, "WriteControlFile: fsync of control file failed: %m");
close(fd);
}
static void
ReadControlFile(void)
{
crc64 crc;
int fd;
/*
* Read data...
*/
fd = BasicOpenFile(ControlFilePath, O_RDWR | PG_BINARY, S_IRUSR | S_IWUSR);
if (fd < 0)
elog(PANIC, "could not open control file (%s): %m", ControlFilePath);
if (read(fd, ControlFile, sizeof(ControlFileData)) != sizeof(ControlFileData))
elog(PANIC, "read from control file failed: %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)
elog(PANIC, "The database cluster was initialized with PG_CONTROL_VERSION %d,\n"
"\tbut the server was compiled with PG_CONTROL_VERSION %d.\n"
"\tIt looks like you need to initdb.",
ControlFile->pg_control_version, PG_CONTROL_VERSION);
/* Now check the CRC. */
INIT_CRC64(crc);
COMP_CRC64(crc,
(char *) ControlFile + sizeof(crc64),
sizeof(ControlFileData) - sizeof(crc64));
FIN_CRC64(crc);
if (!EQ_CRC64(crc, ControlFile->crc))
elog(PANIC, "invalid checksum in control file");
/*
* Do compatibility checking immediately. We do this here for 2
* reasons:
*
* (1) if the database isn't compatible with the backend executable, we
* want to abort before we can possibly do any damage;
*
* (2) this code is executed in the postmaster, so the setlocale() will
* propagate to forked backends, which aren't going to read this file
* for themselves. (These locale settings are considered critical
* compatibility items because they can affect sort order of indexes.)
*/
if (ControlFile->catalog_version_no != CATALOG_VERSION_NO)
elog(PANIC,
"The database cluster was initialized with CATALOG_VERSION_NO %d,\n"
"\tbut the backend was compiled with CATALOG_VERSION_NO %d.\n"
"\tIt looks like you need to initdb.",
ControlFile->catalog_version_no, CATALOG_VERSION_NO);
if (ControlFile->blcksz != BLCKSZ)
elog(PANIC,
"The database cluster was initialized with BLCKSZ %d,\n"
"\tbut the backend was compiled with BLCKSZ %d.\n"
"\tIt looks like you need to initdb.",
ControlFile->blcksz, BLCKSZ);
if (ControlFile->relseg_size != RELSEG_SIZE)
elog(PANIC,
"The database cluster was initialized with RELSEG_SIZE %d,\n"
"\tbut the backend was compiled with RELSEG_SIZE %d.\n"
"\tIt looks like you need to recompile or initdb.",
ControlFile->relseg_size, RELSEG_SIZE);
if (ControlFile->nameDataLen != NAMEDATALEN)
elog(PANIC,
"The database cluster was initialized with NAMEDATALEN %d,\n"
"\tbut the backend was compiled with NAMEDATALEN %d.\n"
"\tIt looks like you need to recompile or initdb.",
ControlFile->nameDataLen, NAMEDATALEN);
if (ControlFile->funcMaxArgs != FUNC_MAX_ARGS)
elog(PANIC,
"The database cluster was initialized with FUNC_MAX_ARGS %d,\n"
"\tbut the backend was compiled with FUNC_MAX_ARGS %d.\n"
"\tIt looks like you need to recompile or initdb.",
ControlFile->funcMaxArgs, FUNC_MAX_ARGS);
#ifdef HAVE_INT64_TIMESTAMP
if (ControlFile->enableIntTimes != TRUE)
elog(PANIC,
"The database cluster was initialized without HAVE_INT64_TIMESTAMP\n"
"\tbut the backend was compiled with HAVE_INT64_TIMESTAMP.\n"
"\tIt looks like you need to recompile or initdb.");
#else
if (ControlFile->enableIntTimes != FALSE)
elog(PANIC,
"The database cluster was initialized with HAVE_INT64_TIMESTAMP\n" "\tbut the backend was compiled without HAVE_INT64_TIMESTAMP.\n"
"\tIt looks like you need to recompile or initdb.");
#endif
if (ControlFile->localeBuflen != LOCALE_NAME_BUFLEN)
elog(PANIC,
"The database cluster was initialized with LOCALE_NAME_BUFLEN %d,\n"
"\tbut the backend was compiled with LOCALE_NAME_BUFLEN %d.\n"
"\tIt looks like you need to initdb.",
ControlFile->localeBuflen, LOCALE_NAME_BUFLEN);
if (setlocale(LC_COLLATE, ControlFile->lc_collate) == NULL)
elog(PANIC,
"The database cluster was initialized with LC_COLLATE '%s',\n"
"\twhich is not recognized by setlocale().\n"
"\tIt looks like you need to initdb.",
ControlFile->lc_collate);
if (setlocale(LC_CTYPE, ControlFile->lc_ctype) == NULL)
elog(PANIC,
"The database cluster was initialized with LC_CTYPE '%s',\n"
"\twhich is not recognized by setlocale().\n"
"\tIt looks like you need to initdb.",
ControlFile->lc_ctype);
/* Make the fixed locale settings visible as GUC variables, too */
SetConfigOption("lc_collate", ControlFile->lc_collate,
PGC_INTERNAL, PGC_S_OVERRIDE);
SetConfigOption("lc_ctype", ControlFile->lc_ctype,
PGC_INTERNAL, PGC_S_OVERRIDE);
}
void
UpdateControlFile(void)
{
int fd;
INIT_CRC64(ControlFile->crc);
COMP_CRC64(ControlFile->crc,
(char *) ControlFile + sizeof(crc64),
sizeof(ControlFileData) - sizeof(crc64));
FIN_CRC64(ControlFile->crc);
fd = BasicOpenFile(ControlFilePath, O_RDWR | PG_BINARY, S_IRUSR | S_IWUSR);
if (fd < 0)
elog(PANIC, "could not open control file (%s): %m", ControlFilePath);
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;
elog(PANIC, "write to control file failed: %m");
}
if (pg_fsync(fd) != 0)
elog(PANIC, "fsync of control file failed: %m");
close(fd);
}
/*
* Initialization of shared memory for XLOG
*/
int
XLOGShmemSize(void)
{
if (XLOGbuffers < MinXLOGbuffers)
XLOGbuffers = MinXLOGbuffers;
return MAXALIGN(sizeof(XLogCtlData) + sizeof(XLogRecPtr) * XLOGbuffers)
+ BLCKSZ * XLOGbuffers +
MAXALIGN(sizeof(ControlFileData));
}
void
XLOGShmemInit(void)
{
bool found;
/* this must agree with space requested by XLOGShmemSize() */
if (XLOGbuffers < MinXLOGbuffers)
XLOGbuffers = MinXLOGbuffers;
XLogCtl = (XLogCtlData *)
ShmemInitStruct("XLOG Ctl",
MAXALIGN(sizeof(XLogCtlData) +
sizeof(XLogRecPtr) * XLOGbuffers)
+ BLCKSZ * XLOGbuffers,
&found);
Assert(!found);
ControlFile = (ControlFileData *)
ShmemInitStruct("Control File", sizeof(ControlFileData), &found);
Assert(!found);
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.
*/
XLogCtl->xlblocks = (XLogRecPtr *)
(((char *) XLogCtl) + sizeof(XLogCtlData));
memset(XLogCtl->xlblocks, 0, sizeof(XLogRecPtr) * XLOGbuffers);
/*
* Here, on the other hand, we must MAXALIGN to ensure the page
* buffers have worst-case alignment.
*/
XLogCtl->pages =
((char *) XLogCtl) + MAXALIGN(sizeof(XLogCtlData) +
sizeof(XLogRecPtr) * XLOGbuffers);
memset(XLogCtl->pages, 0, BLCKSZ * XLOGbuffers);
/*
* Do basic initialization of XLogCtl shared data. (StartupXLOG will
* fill in additional info.)
*/
XLogCtl->XLogCacheByte = BLCKSZ * XLOGbuffers;
XLogCtl->XLogCacheBlck = XLOGbuffers - 1;
XLogCtl->Insert.currpage = (XLogPageHeader) (XLogCtl->pages);
SpinLockInit(&XLogCtl->info_lck);
/*
* If we are not in bootstrap mode, pg_control should already exist.
* Read and validate it immediately (see comments in ReadControlFile()
* for the reasons why).
*/
if (!IsBootstrapProcessingMode())
ReadControlFile();
}
/*
* This func must be called ONCE on system install. It creates pg_control
* and the initial XLOG segment.
*/
void
BootStrapXLOG(void){
CheckPoint checkPoint;
char *buffer;
XLogPageHeader page;
XLogRecord *record;
bool use_existent;
crc64 crc;
/* Use malloc() to ensure buffer is MAXALIGNED */
buffer = (char *) malloc(BLCKSZ);
page = (XLogPageHeader) buffer;
checkPoint.redo.xlogid = 0;
checkPoint.redo.xrecoff = SizeOfXLogPHD;
checkPoint.undo = checkPoint.redo;
checkPoint.ThisStartUpID = 0;
checkPoint.nextXid = FirstNormalTransactionId;
checkPoint.nextOid = BootstrapObjectIdData;
checkPoint.time = time(NULL);
ShmemVariableCache->nextXid = checkPoint.nextXid;
ShmemVariableCache->nextOid = checkPoint.nextOid;
ShmemVariableCache->oidCount = 0;
memset(buffer, 0, BLCKSZ);
page->xlp_magic = XLOG_PAGE_MAGIC;
page->xlp_info = 0;
page->xlp_sui = checkPoint.ThisStartUpID;
page->xlp_pageaddr.xlogid = 0;
page->xlp_pageaddr.xrecoff = 0;
record = (XLogRecord *) ((char *) page + SizeOfXLogPHD);
record->xl_prev.xlogid = 0;
record->xl_prev.xrecoff = 0;
record->xl_xact_prev = record->xl_prev;
record->xl_xid = InvalidTransactionId;
record->xl_len = sizeof(checkPoint);
record->xl_info = XLOG_CHECKPOINT_SHUTDOWN;
record->xl_rmid = RM_XLOG_ID;
memcpy(XLogRecGetData(record), &checkPoint, sizeof(checkPoint));
INIT_CRC64(crc);
COMP_CRC64(crc, &checkPoint, sizeof(checkPoint));
COMP_CRC64(crc, (char *) record + sizeof(crc64),
SizeOfXLogRecord - sizeof(crc64));
FIN_CRC64(crc);
record->xl_crc = crc;
use_existent = false;
openLogFile = XLogFileInit(0, 0, &use_existent, false);
errno = 0;
if (write(openLogFile, buffer, BLCKSZ) != BLCKSZ)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
elog(PANIC, "BootStrapXLOG failed to write log file: %m");
}
if (pg_fsync(openLogFile) != 0)
elog(PANIC, "BootStrapXLOG failed to fsync log file: %m");
close(openLogFile);
openLogFile = -1;
memset(ControlFile, 0, sizeof(ControlFileData));
/* Initialize pg_control status fields */
ControlFile->state = DB_SHUTDOWNED;
ControlFile->time = checkPoint.time;
ControlFile->logId = 0; ControlFile->logSeg = 1;
ControlFile->checkPoint = checkPoint.redo;
ControlFile->checkPointCopy = checkPoint;
/* some additional ControlFile fields are set in WriteControlFile() */
WriteControlFile();
/* Bootstrap the commit log, too */
BootStrapCLOG();
}
static char *
str_time(time_t tnow)
{
static char buf[32];
strftime(buf, sizeof(buf),
"%Y-%m-%d %H:%M:%S %Z",
localtime(&tnow));
return buf;
}
/*
* This must be called ONCE during postmaster or standalone-backend startup
*/
void
StartupXLOG(void)
{
XLogCtlInsert *Insert;
CheckPoint checkPoint;
bool wasShutdown;
XLogRecPtr RecPtr,
LastRec,
checkPointLoc,
EndOfLog;
XLogRecord *record;
char *buffer;
/* Use malloc() to ensure record buffer is MAXALIGNED */
buffer = (char *) malloc(_INTL_MAXLOGRECSZ);
CritSectionCount++;
/*
* 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->logSeg == 0 ||
ControlFile->state < DB_SHUTDOWNED ||
ControlFile->state > DB_IN_PRODUCTION ||
!XRecOffIsValid(ControlFile->checkPoint.xrecoff))
elog(PANIC, "control file context is broken");
if (ControlFile->state == DB_SHUTDOWNED)
elog(LOG, "database system was shut down at %s",
str_time(ControlFile->time));
else if (ControlFile->state == DB_SHUTDOWNING)
elog(LOG, "database system shutdown was interrupted at %s",
str_time(ControlFile->time));
else if (ControlFile->state == DB_IN_RECOVERY)
elog(LOG, "database system was interrupted being in recovery at %s\n"
"\tThis probably means that some data blocks are corrupted\n"
"\tand you will have to use the last backup for recovery.",
str_time(ControlFile->time));
else if (ControlFile->state == DB_IN_PRODUCTION) elog(LOG, "database system was interrupted at %s",
str_time(ControlFile->time));
/* This is just to allow attaching to startup process with a debugger */
#ifdef XLOG_REPLAY_DELAY
if (XLOG_DEBUG && ControlFile->state != DB_SHUTDOWNED)
sleep(60);
#endif
/*
* Get the last valid checkpoint record. If the latest one according
* to pg_control is broken, try the next-to-last one.
*/
record = ReadCheckpointRecord(ControlFile->checkPoint, 1, buffer);
if (record != NULL)
{
checkPointLoc = ControlFile->checkPoint;
elog(LOG, "checkpoint record is at %X/%X",
checkPointLoc.xlogid, checkPointLoc.xrecoff);
}
else
{
record = ReadCheckpointRecord(ControlFile->prevCheckPoint, 2, buffer);
if (record != NULL)
{
checkPointLoc = ControlFile->prevCheckPoint;
elog(LOG, "using previous checkpoint record at %X/%X",
checkPointLoc.xlogid, checkPointLoc.xrecoff);
InRecovery = true; /* force recovery even if SHUTDOWNED */
}
else
elog(PANIC, "unable to locate a valid checkpoint record");
}
LastRec = RecPtr = checkPointLoc;
memcpy(&checkPoint, XLogRecGetData(record), sizeof(CheckPoint));
wasShutdown = (record->xl_info == XLOG_CHECKPOINT_SHUTDOWN);
elog(LOG, "redo record is at %X/%X; undo record is at %X/%X; shutdown %s",
checkPoint.redo.xlogid, checkPoint.redo.xrecoff,
checkPoint.undo.xlogid, checkPoint.undo.xrecoff,
wasShutdown ? "TRUE" : "FALSE");
elog(LOG, "next transaction id: %u; next oid: %u",
checkPoint.nextXid, checkPoint.nextOid);
if (!TransactionIdIsNormal(checkPoint.nextXid))
elog(PANIC, "invalid next transaction id");
ShmemVariableCache->nextXid = checkPoint.nextXid;
ShmemVariableCache->nextOid = checkPoint.nextOid;
ShmemVariableCache->oidCount = 0;
ThisStartUpID = checkPoint.ThisStartUpID;
RedoRecPtr = XLogCtl->Insert.RedoRecPtr =
XLogCtl->SavedRedoRecPtr = checkPoint.redo;
if (XLByteLT(RecPtr, checkPoint.redo))
elog(PANIC, "invalid redo in checkpoint record");
if (checkPoint.undo.xrecoff == 0)
checkPoint.undo = RecPtr;
if (XLByteLT(checkPoint.undo, RecPtr) ||
XLByteLT(checkPoint.redo, RecPtr))
{
if (wasShutdown)
elog(PANIC, "invalid redo/undo record in shutdown checkpoint");
InRecovery = true;
}
else if (ControlFile->state != DB_SHUTDOWNED)
InRecovery = true;
/* REDO */ if (InRecovery)
{
int rmid;
elog(LOG, "database system was not properly shut down; "
"automatic recovery in progress");
ControlFile->state = DB_IN_RECOVERY;
ControlFile->time = time(NULL);
UpdateControlFile();
/* Start up the recovery environment */
XLogInitRelationCache();
for (rmid = 0; rmid <= RM_MAX_ID; rmid++)
{
if (RmgrTable[rmid].rm_startup != NULL)
RmgrTable[rmid].rm_startup();
}
/* Is REDO required ? */
if (XLByteLT(checkPoint.redo, RecPtr))
record = ReadRecord(&(checkPoint.redo), PANIC, buffer);
else
{
/* read past CheckPoint record */
record = ReadRecord(NULL, LOG, buffer);
}
if (record != NULL)
{
InRedo = true;
elog(LOG, "redo starts at %X/%X",
ReadRecPtr.xlogid, ReadRecPtr.xrecoff);
do
{
/* nextXid must be beyond record's xid */
if (TransactionIdFollowsOrEquals(record->xl_xid,
ShmemVariableCache->nextXid))
{
ShmemVariableCache->nextXid = record->xl_xid;
TransactionIdAdvance(ShmemVariableCache->nextXid);
}
if (XLOG_DEBUG)
{
char buf[8192];
sprintf(buf, "REDO @ %X/%X; LSN %X/%X: ",
ReadRecPtr.xlogid, ReadRecPtr.xrecoff,
EndRecPtr.xlogid, EndRecPtr.xrecoff);
xlog_outrec(buf, record);
strcat(buf, " - ");
RmgrTable[record->xl_rmid].rm_desc(buf,
record->xl_info, XLogRecGetData(record));
elog(LOG, "%s", buf);
}
if (record->xl_info & XLR_BKP_BLOCK_MASK)
RestoreBkpBlocks(record, EndRecPtr);
RmgrTable[record->xl_rmid].rm_redo(EndRecPtr, record);
record = ReadRecord(NULL, LOG, buffer);
} while (record != NULL);
elog(LOG, "redo done at %X/%X",
ReadRecPtr.xlogid, ReadRecPtr.xrecoff);
LastRec = ReadRecPtr;
InRedo = false;
}
else
elog(LOG, "redo is not required");
}
/*
* Init xlog buffer cache using the block containing the last valid
* record from the previous incarnation.
*/
record = ReadRecord(&LastRec, PANIC, buffer);
EndOfLog = EndRecPtr;
XLByteToPrevSeg(EndOfLog, openLogId, openLogSeg);
openLogFile = XLogFileOpen(openLogId, openLogSeg, false);
openLogOff = 0;
ControlFile->logId = openLogId;
ControlFile->logSeg = openLogSeg + 1;
Insert = &XLogCtl->Insert;
Insert->PrevRecord = LastRec;
/*
* If the next record will go to the new page then initialize for that
* one.
*/
if ((BLCKSZ - EndOfLog.xrecoff % BLCKSZ) < SizeOfXLogRecord)
EndOfLog.xrecoff += (BLCKSZ - EndOfLog.xrecoff % BLCKSZ);
if (EndOfLog.xrecoff % BLCKSZ == 0)
{
XLogRecPtr NewPageEndPtr;
NewPageEndPtr = EndOfLog;
if (NewPageEndPtr.xrecoff >= XLogFileSize)
{
/* crossing a logid boundary */
NewPageEndPtr.xlogid += 1;
NewPageEndPtr.xrecoff = BLCKSZ;
}
else
NewPageEndPtr.xrecoff += BLCKSZ;
XLogCtl->xlblocks[0] = NewPageEndPtr;
Insert->currpage->xlp_magic = XLOG_PAGE_MAGIC;
if (InRecovery)
Insert->currpage->xlp_sui = ThisStartUpID;
else
Insert->currpage->xlp_sui = ThisStartUpID + 1;
Insert->currpage->xlp_pageaddr.xlogid = NewPageEndPtr.xlogid;
Insert->currpage->xlp_pageaddr.xrecoff = NewPageEndPtr.xrecoff - BLCKSZ;
/* rest of buffer was zeroed in XLOGShmemInit */
Insert->currpos = (char *) Insert->currpage + SizeOfXLogPHD;
}
else
{
XLogCtl->xlblocks[0].xlogid = openLogId;
XLogCtl->xlblocks[0].xrecoff =
((EndOfLog.xrecoff - 1) / BLCKSZ + 1) * 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 - BLCKSZ) % XLogSegSize);
memcpy((char *) Insert->currpage, readBuf, BLCKSZ);
Insert->currpos = (char *) Insert->currpage +
(EndOfLog.xrecoff + BLCKSZ - XLogCtl->xlblocks[0].xrecoff);
/* Make sure rest of page is zero */
memset(Insert->currpos, 0, INSERT_FREESPACE(Insert));
}
LogwrtResult.Write = LogwrtResult.Flush = EndOfLog;
XLogCtl->Write.LogwrtResult = LogwrtResult;
Insert->LogwrtResult = LogwrtResult;
XLogCtl->LogwrtResult = LogwrtResult;
XLogCtl->LogwrtRqst.Write = EndOfLog;
XLogCtl->LogwrtRqst.Flush = EndOfLog;
#ifdef NOT_USED
/* UNDO */
if (InRecovery)
{
RecPtr = ReadRecPtr;
if (XLByteLT(checkPoint.undo, RecPtr))
{
elog(LOG, "undo starts at %X/%X",
RecPtr.xlogid, RecPtr.xrecoff);
do
{
record = ReadRecord(&RecPtr, PANIC, buffer);
if (TransactionIdIsValid(record->xl_xid) &&
!TransactionIdDidCommit(record->xl_xid))
RmgrTable[record->xl_rmid].rm_undo(EndRecPtr, record);
RecPtr = record->xl_prev;
} while (XLByteLE(checkPoint.undo, RecPtr));
elog(LOG, "undo done at %X/%X",
ReadRecPtr.xlogid, ReadRecPtr.xrecoff);
}
else
elog(LOG, "undo is not required");
}
#endif
if (InRecovery)
{
int rmid;
/*
* Allow resource managers to do any required cleanup.
*/
for (rmid = 0; rmid <= RM_MAX_ID; rmid++)
{
if (RmgrTable[rmid].rm_cleanup != NULL)
RmgrTable[rmid].rm_cleanup();
}
/* suppress in-transaction check in CreateCheckPoint */
MyLastRecPtr.xrecoff = 0;
MyXactMadeXLogEntry = false;
MyXactMadeTempRelUpdate = false;
/*
* Perform a new checkpoint to update our recovery activity to disk.
*
* In case we had to use the secondary checkpoint, make sure that
* it will still be shown as the secondary checkpoint after this
* CreateCheckPoint operation; we don't want the broken primary
* checkpoint to become prevCheckPoint...
*/
ControlFile->checkPoint = checkPointLoc;
CreateCheckPoint(true, true);
/*
* Close down recovery environment
*/
XLogCloseRelationCache();
}
/*
* Preallocate additional log files, if wanted.
*/
PreallocXlogFiles(EndOfLog);
InRecovery = false;
ControlFile->state = DB_IN_PRODUCTION;
ControlFile->time = time(NULL);
UpdateControlFile();
ThisStartUpID++;
XLogCtl->ThisStartUpID = ThisStartUpID;
/* Start up the commit log, too */
StartupCLOG();
elog(LOG, "database system is ready");
CritSectionCount--;
/* Shut down readFile facility, free space */
if (readFile >= 0)
{
close(readFile);
readFile = -1;
}
if (readBuf)
{
free(readBuf);
readBuf = NULL;
}
free(buffer);
}
/*
* Subroutine to try to fetch and validate a prior checkpoint record.
* whichChkpt = 1 for "primary", 2 for "secondary", merely informative
*/
static XLogRecord *
ReadCheckpointRecord(XLogRecPtr RecPtr,
int whichChkpt,
char *buffer)
{
XLogRecord *record;
if (!XRecOffIsValid(RecPtr.xrecoff))
{
elog(LOG, (whichChkpt == 1 ?
"invalid primary checkpoint link in control file" :
"invalid secondary checkpoint link in control file"));
return NULL;
}
record = ReadRecord(&RecPtr, LOG, buffer);
if (record == NULL)
{
elog(LOG, (whichChkpt == 1 ?
"invalid primary checkpoint record" :
"invalid secondary checkpoint record"));
return NULL;
}
if (record->xl_rmid != RM_XLOG_ID)
{
elog(LOG, (whichChkpt == 1 ?
"invalid resource manager id in primary checkpoint record" :
"invalid resource manager id in secondary checkpoint record"));
return NULL;
}
if (record->xl_info != XLOG_CHECKPOINT_SHUTDOWN &&
record->xl_info != XLOG_CHECKPOINT_ONLINE)
{
elog(LOG, (whichChkpt == 1 ?
"invalid xl_info in primary checkpoint record" :
"invalid xl_info in secondary checkpoint record"));
return NULL; }
if (record->xl_len != sizeof(CheckPoint))
{
elog(LOG, (whichChkpt == 1 ?
"invalid length of primary checkpoint record" :
"invalid length of secondary checkpoint record"));
return NULL;
}
return record;
}
/*
* Postmaster uses this to initialize ThisStartUpID & RedoRecPtr from
* XLogCtlData located in shmem after successful startup.
*/
void
SetThisStartUpID(void)
{
ThisStartUpID = XLogCtl->ThisStartUpID;
RedoRecPtr = XLogCtl->SavedRedoRecPtr;
}
/*
* CheckPoint process called by postmaster saves copy of new RedoRecPtr
* in shmem (using SetSavedRedoRecPtr). When checkpointer completes,
* postmaster calls GetSavedRedoRecPtr to update its own copy of RedoRecPtr,
* so that subsequently-spawned backends will start out with a reasonably
* up-to-date local RedoRecPtr. Since these operations are not protected by
* any lock and copying an XLogRecPtr isn't atomic, it's unsafe to use either
* of these routines at other times!
*/
void
SetSavedRedoRecPtr(void)
{
XLogCtl->SavedRedoRecPtr = RedoRecPtr;
}
void
GetSavedRedoRecPtr(void)
{
RedoRecPtr = XLogCtl->SavedRedoRecPtr;
}
/*
* 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_NoHoldoff(&xlogctl->info_lck);
Assert(XLByteLE(RedoRecPtr, xlogctl->Insert.RedoRecPtr));
RedoRecPtr = xlogctl->Insert.RedoRecPtr;
SpinLockRelease_NoHoldoff(&xlogctl->info_lck);
return RedoRecPtr;
}
/*
* This must be called ONCE during postmaster or standalone-backend shutdown
*/
void
ShutdownXLOG(void)
{
elog(LOG, "shutting down");
/* suppress in-transaction check in CreateCheckPoint */
MyLastRecPtr.xrecoff = 0;
MyXactMadeXLogEntry = false;
MyXactMadeTempRelUpdate = false;
CritSectionCount++;
CreateDummyCaches();
CreateCheckPoint(true, true);
ShutdownCLOG();
CritSectionCount--;
elog(LOG, "database system is shut down");
}
/*
* Perform a checkpoint --- either during shutdown, or on-the-fly
*
* If force is true, we force a checkpoint regardless of whether any XLOG
* activity has occurred since the last one.
*/
void
CreateCheckPoint(bool shutdown, bool force)
{
CheckPoint checkPoint;
XLogRecPtr recptr;
XLogCtlInsert *Insert = &XLogCtl->Insert;
XLogRecData rdata;
uint32 freespace;
uint32 _logId;
uint32 _logSeg;
if (MyXactMadeXLogEntry)
elog(ERROR, "CreateCheckPoint: cannot be called inside transaction block");
/*
* Acquire CheckpointLock to ensure only one checkpoint happens at a time.
*
* The CheckpointLock can be held for quite a while, which is not good
* because we won't respond to a cancel/die request while waiting for
* an LWLock. (But the alternative of using a regular lock won't work
* for background checkpoint processes, which are not regular
* backends.) So, rather than use a plain LWLockAcquire, use this
* kluge to allow an interrupt to be accepted while we are waiting:
*/
while (!LWLockConditionalAcquire(CheckpointLock, LW_EXCLUSIVE))
{
CHECK_FOR_INTERRUPTS();
sleep(1);
}
/*
* Use a critical section to force system panic if we have trouble.
*/
START_CRIT_SECTION();
if (shutdown)
{
ControlFile->state = DB_SHUTDOWNING;
ControlFile->time = time(NULL);
UpdateControlFile();
}
memset(&checkPoint, 0, sizeof(checkPoint));
checkPoint.ThisStartUpID = ThisStartUpID;
checkPoint.time = time(NULL);
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 (!shutdown && !force)
{
XLogRecPtr curInsert;
INSERT_RECPTR(curInsert, Insert, Insert->curridx);
if (curInsert.xlogid == ControlFile->checkPoint.xlogid &&
curInsert.xrecoff == ControlFile->checkPoint.xrecoff +
MAXALIGN(SizeOfXLogRecord + sizeof(CheckPoint)) &&
ControlFile->checkPoint.xlogid ==
ControlFile->checkPointCopy.redo.xlogid &&
ControlFile->checkPoint.xrecoff ==
ControlFile->checkPointCopy.redo.xrecoff)
{
LWLockRelease(WALInsertLock);
LWLockRelease(CheckpointLock);
END_CRIT_SECTION();
return;
}
}
/*
* Compute new REDO record ptr = location of next XLOG record.
*
* NB: this is NOT necessarily where the checkpoint record itself will
* be, since other backends may insert more XLOG records while we're
* off doing the buffer flush work. Those XLOG records are logically
* after the checkpoint, even though physically before it. Got that?
*/
freespace = INSERT_FREESPACE(Insert);
if (freespace < SizeOfXLogRecord)
{
(void) AdvanceXLInsertBuffer();
/* OK to ignore update return flag, since we will do flush anyway */
freespace = BLCKSZ - SizeOfXLogPHD;
}
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_NoHoldoff(&xlogctl->info_lck);
RedoRecPtr = xlogctl->Insert.RedoRecPtr = checkPoint.redo;
SpinLockRelease_NoHoldoff(&xlogctl->info_lck);
}
/*
* Get UNDO record ptr - this is oldest of PGPROC->logRec values. We
* do this while holding insert lock to ensure that we won't miss any
* about-to-commit transactions (UNDO must include all xacts that have
* commits after REDO point).
*
* XXX temporarily ifdef'd out to avoid three-way deadlock condition:
* GetUndoRecPtr needs to grab SInvalLock to ensure that it is looking
* at a stable set of proc records, but grabbing SInvalLock while
* holding WALInsertLock is no good. GetNewTransactionId may cause a
* WAL record to be written while holding XidGenLock, and
* GetSnapshotData needs to get XidGenLock while holding SInvalLock,
* so there's a risk of deadlock. Need to find a better solution. See
* pgsql-hackers discussion of 17-Dec-01.
*/
#ifdef NOT_USED
checkPoint.undo = GetUndoRecPtr();
if (shutdown && checkPoint.undo.xrecoff != 0)
elog(PANIC, "active transaction while database system is shutting down");
#endif
/*
* Now we can release insert lock, allowing other xacts to proceed
* even while we are flushing disk buffers.
*/
LWLockRelease(WALInsertLock);
/*
* Get the other info we need for the checkpoint record.
*/
LWLockAcquire(XidGenLock, LW_SHARED);
checkPoint.nextXid = ShmemVariableCache->nextXid;
LWLockRelease(XidGenLock);
LWLockAcquire(OidGenLock, LW_SHARED);
checkPoint.nextOid = ShmemVariableCache->nextOid;
if (!shutdown)
checkPoint.nextOid += ShmemVariableCache->oidCount;
LWLockRelease(OidGenLock);
/*
* 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();
CheckPointCLOG();
FlushBufferPool();
START_CRIT_SECTION();
/*
* Now insert the checkpoint record into XLOG.
*/
rdata.buffer = InvalidBuffer;
rdata.data = (char *) (&checkPoint);
rdata.len = sizeof(checkPoint);
rdata.next = NULL;
recptr = XLogInsert(RM_XLOG_ID,
shutdown ? XLOG_CHECKPOINT_SHUTDOWN :
XLOG_CHECKPOINT_ONLINE,
&rdata);
XLogFlush(recptr);
/*
* We now have ProcLastRecPtr = start of actual checkpoint record,
* recptr = end of actual checkpoint record.
*/
if (shutdown && !XLByteEQ(checkPoint.redo, ProcLastRecPtr))
elog(PANIC, "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.
*
* With UNDO support: oldest item is redo or undo, whichever is older;
* but watch out for case that undo = 0.
*
* Without UNDO support: just use the redo pointer. This allows xlog
* space to be freed much faster when there are long-running
* transactions.
*/
#ifdef NOT_USED
if (ControlFile->checkPointCopy.undo.xrecoff != 0 &&
XLByteLT(ControlFile->checkPointCopy.undo,
ControlFile->checkPointCopy.redo))
XLByteToSeg(ControlFile->checkPointCopy.undo, _logId, _logSeg);
else
#endif
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 = time(NULL);
UpdateControlFile();
LWLockRelease(ControlFileLock);
/*
* We are now done with critical updates; no need for system panic if
* we have trouble while fooling with offline log segments.
*/
END_CRIT_SECTION();
/*
* Delete offline log files (those no longer needed even for previous
* checkpoint).
*/
if (_logId || _logSeg)
{
PrevLogSeg(_logId, _logSeg);
MoveOfflineLogs(_logId, _logSeg, recptr);
}
/*
* Make more log segments if needed. (Do this after deleting offline
* log segments, to avoid having peak disk space usage higher than
* necessary.)
*/
if (!shutdown)
PreallocXlogFiles(recptr);
LWLockRelease(CheckpointLock);
}
/*
* Write a NEXTOID log record */
void
XLogPutNextOid(Oid nextOid)
{
XLogRecData rdata;
rdata.buffer = InvalidBuffer;
rdata.data = (char *) (&nextOid);
rdata.len = sizeof(Oid);
rdata.next = NULL;
(void) XLogInsert(RM_XLOG_ID, XLOG_NEXTOID, &rdata);
}
/*
* XLOG resource manager's routines
*/
void
xlog_redo(XLogRecPtr lsn, XLogRecord *record)
{
uint8 info = record->xl_info & ~XLR_INFO_MASK;
if (info == XLOG_NEXTOID)
{
Oid nextOid;
memcpy(&nextOid, XLogRecGetData(record), sizeof(Oid));
if (ShmemVariableCache->nextOid < nextOid)
{
ShmemVariableCache->nextOid = nextOid;
ShmemVariableCache->oidCount = 0;
}
}
else if (info == XLOG_CHECKPOINT_SHUTDOWN)
{
CheckPoint checkPoint;
memcpy(&checkPoint, XLogRecGetData(record), sizeof(CheckPoint));
/* In a SHUTDOWN checkpoint, believe the counters exactly */
ShmemVariableCache->nextXid = checkPoint.nextXid;
ShmemVariableCache->nextOid = checkPoint.nextOid;
ShmemVariableCache->oidCount = 0;
}
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;
}
}
}
void
xlog_undo(XLogRecPtr lsn, XLogRecord *record)
{
}
void
xlog_desc(char *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;
sprintf(buf + strlen(buf), "checkpoint: redo %X/%X; undo %X/%X; "
"sui %u; xid %u; oid %u; %s",
checkpoint->redo.xlogid, checkpoint->redo.xrecoff,
checkpoint->undo.xlogid, checkpoint->undo.xrecoff,
checkpoint->ThisStartUpID, checkpoint->nextXid,
checkpoint->nextOid,
(info == XLOG_CHECKPOINT_SHUTDOWN) ? "shutdown" : "online");
}
else if (info == XLOG_NEXTOID)
{
Oid nextOid;
memcpy(&nextOid, rec, sizeof(Oid));
sprintf(buf + strlen(buf), "nextOid: %u", nextOid);
}
else
strcat(buf, "UNKNOWN");
}
static void
xlog_outrec(char *buf, XLogRecord *record)
{
int bkpb;
int i;
sprintf(buf + strlen(buf), "prev %X/%X; xprev %X/%X; xid %u",
record->xl_prev.xlogid, record->xl_prev.xrecoff,
record->xl_xact_prev.xlogid, record->xl_xact_prev.xrecoff,
record->xl_xid);
for (i = 0, bkpb = 0; i < XLR_MAX_BKP_BLOCKS; i++)
{
if (!(record->xl_info & (XLR_SET_BKP_BLOCK(i))))
continue;
bkpb++;
}
if (bkpb)
sprintf(buf + strlen(buf), "; bkpb %d", bkpb);
sprintf(buf + strlen(buf), ": %s",
RmgrTable[record->xl_rmid].rm_name);
}
/*
* GUC support
*/
const char *
assign_xlog_sync_method(const char *method, bool doit, bool interactive)
{
int new_sync_method;
int new_sync_bit;
if (strcasecmp(method, "fsync") == 0)
{
new_sync_method = SYNC_METHOD_FSYNC;
new_sync_bit = 0;
}
#ifdef HAVE_FDATASYNC
else if (strcasecmp(method, "fdatasync") == 0)
{
new_sync_method = SYNC_METHOD_FDATASYNC;
new_sync_bit = 0;
}
#endif#ifdef OPEN_SYNC_FLAG
else if (strcasecmp(method, "open_sync") == 0)
{
new_sync_method = SYNC_METHOD_OPEN;
new_sync_bit = OPEN_SYNC_FLAG;
}
#endif
#ifdef OPEN_DATASYNC_FLAG
else if (strcasecmp(method, "open_datasync") == 0)
{
new_sync_method = SYNC_METHOD_OPEN;
new_sync_bit = OPEN_DATASYNC_FLAG;
}
#endif
else
return NULL;
if (!doit)
return method;
if (sync_method != new_sync_method || open_sync_bit != new_sync_bit)
{
/*
* To ensure that no blocks escape unsynced, force an fsync on the
* currently open log segment (if any). Also, if the open flag is
* changing, close the log file so it will be reopened (with new
* flag bit) at next use.
*/
if (openLogFile >= 0)
{
if (pg_fsync(openLogFile) != 0)
elog(PANIC, "fsync of log file %u, segment %u failed: %m",
openLogId, openLogSeg);
if (open_sync_bit != new_sync_bit)
{
if (close(openLogFile) != 0)
elog(PANIC, "close of log file %u, segment %u failed: %m",
openLogId, openLogSeg);
openLogFile = -1;
}
}
sync_method = new_sync_method;
open_sync_bit = new_sync_bit;
}
return method;
}
/*
* Issue appropriate kind of fsync (if any) on the current XLOG output file
*/
static void
issue_xlog_fsync(void)
{
switch (sync_method)
{
case SYNC_METHOD_FSYNC:
if (pg_fsync(openLogFile) != 0)
elog(PANIC, "fsync of log file %u, segment %u failed: %m",
openLogId, openLogSeg);
break;
#ifdef HAVE_FDATASYNC
case SYNC_METHOD_FDATASYNC:
if (pg_fdatasync(openLogFile) != 0)
elog(PANIC, "fdatasync of log file %u, segment %u failed: %m",
openLogId, openLogSeg);
break;
#endif
case SYNC_METHOD_OPEN: /* write synced it already */
break;
default:
elog(PANIC, "bogus wal_sync_method %d", sync_method);
break;
}
}