mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-10-02 08:21:17 +02:00
f6e8730d11
avoid this problem in the future.)
215 lines
8.0 KiB
C
215 lines
8.0 KiB
C
/*
|
|
* xlog.h
|
|
*
|
|
* PostgreSQL transaction log manager
|
|
*
|
|
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
* $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.86 2007/11/15 22:25:17 momjian Exp $
|
|
*/
|
|
#ifndef XLOG_H
|
|
#define XLOG_H
|
|
|
|
#include "access/rmgr.h"
|
|
#include "access/xlogdefs.h"
|
|
#include "lib/stringinfo.h"
|
|
#include "storage/buf.h"
|
|
#include "utils/pg_crc.h"
|
|
#include "utils/timestamp.h"
|
|
|
|
|
|
/*
|
|
* The overall layout of an XLOG record is:
|
|
* Fixed-size header (XLogRecord struct)
|
|
* rmgr-specific data
|
|
* BkpBlock
|
|
* backup block data
|
|
* BkpBlock
|
|
* backup block data
|
|
* ...
|
|
*
|
|
* where there can be zero to three backup blocks (as signaled by xl_info flag
|
|
* bits). XLogRecord structs always start on MAXALIGN boundaries in the WAL
|
|
* files, and we round up SizeOfXLogRecord so that the rmgr data is also
|
|
* guaranteed to begin on a MAXALIGN boundary. However, no padding is added
|
|
* to align BkpBlock structs or backup block data.
|
|
*
|
|
* NOTE: xl_len counts only the rmgr data, not the XLogRecord header,
|
|
* and also not any backup blocks. xl_tot_len counts everything. Neither
|
|
* length field is rounded up to an alignment boundary.
|
|
*/
|
|
typedef struct XLogRecord
|
|
{
|
|
pg_crc32 xl_crc; /* CRC for this record */
|
|
XLogRecPtr xl_prev; /* ptr to previous record in log */
|
|
TransactionId xl_xid; /* xact id */
|
|
uint32 xl_tot_len; /* total len of entire record */
|
|
uint32 xl_len; /* total len of rmgr data */
|
|
uint8 xl_info; /* flag bits, see below */
|
|
RmgrId xl_rmid; /* resource manager for this record */
|
|
|
|
/* Depending on MAXALIGN, there are either 2 or 6 wasted bytes here */
|
|
|
|
/* ACTUAL LOG DATA FOLLOWS AT END OF STRUCT */
|
|
|
|
} XLogRecord;
|
|
|
|
#define SizeOfXLogRecord MAXALIGN(sizeof(XLogRecord))
|
|
|
|
#define XLogRecGetData(record) ((char*) (record) + SizeOfXLogRecord)
|
|
|
|
/*
|
|
* XLOG uses only low 4 bits of xl_info. High 4 bits may be used by rmgr.
|
|
*/
|
|
#define XLR_INFO_MASK 0x0F
|
|
|
|
/*
|
|
* If we backed up any disk blocks with the XLOG record, we use flag bits in
|
|
* xl_info to signal it. We support backup of up to 3 disk blocks per XLOG
|
|
* record.
|
|
*/
|
|
#define XLR_BKP_BLOCK_MASK 0x0E /* all info bits used for bkp blocks */
|
|
#define XLR_MAX_BKP_BLOCKS 3
|
|
#define XLR_SET_BKP_BLOCK(iblk) (0x08 >> (iblk))
|
|
#define XLR_BKP_BLOCK_1 XLR_SET_BKP_BLOCK(0) /* 0x08 */
|
|
#define XLR_BKP_BLOCK_2 XLR_SET_BKP_BLOCK(1) /* 0x04 */
|
|
#define XLR_BKP_BLOCK_3 XLR_SET_BKP_BLOCK(2) /* 0x02 */
|
|
|
|
/*
|
|
* Bit 0 of xl_info is set if the backed-up blocks could safely be removed
|
|
* from a compressed version of XLOG (that is, they are backed up only to
|
|
* prevent partial-page-write problems, and not to ensure consistency of PITR
|
|
* recovery). The compression algorithm would need to extract data from the
|
|
* blocks to create an equivalent non-full-page XLOG record.
|
|
*/
|
|
#define XLR_BKP_REMOVABLE 0x01
|
|
|
|
/* Sync methods */
|
|
#define SYNC_METHOD_FSYNC 0
|
|
#define SYNC_METHOD_FDATASYNC 1
|
|
#define SYNC_METHOD_OPEN 2 /* for O_SYNC and O_DSYNC */
|
|
#define SYNC_METHOD_FSYNC_WRITETHROUGH 3
|
|
extern int sync_method;
|
|
|
|
/*
|
|
* The rmgr data to be written by XLogInsert() is defined by a chain of
|
|
* one or more XLogRecData structs. (Multiple structs would be used when
|
|
* parts of the source data aren't physically adjacent in memory, or when
|
|
* multiple associated buffers need to be specified.)
|
|
*
|
|
* If buffer is valid then XLOG will check if buffer must be backed up
|
|
* (ie, whether this is first change of that page since last checkpoint).
|
|
* If so, the whole page contents are attached to the XLOG record, and XLOG
|
|
* sets XLR_BKP_BLOCK_X bit in xl_info. Note that the buffer must be pinned
|
|
* and exclusive-locked by the caller, so that it won't change under us.
|
|
* NB: when the buffer is backed up, we DO NOT insert the data pointed to by
|
|
* this XLogRecData struct into the XLOG record, since we assume it's present
|
|
* in the buffer. Therefore, rmgr redo routines MUST pay attention to
|
|
* XLR_BKP_BLOCK_X to know what is actually stored in the XLOG record.
|
|
* The i'th XLR_BKP_BLOCK bit corresponds to the i'th distinct buffer
|
|
* value (ignoring InvalidBuffer) appearing in the rdata chain.
|
|
*
|
|
* When buffer is valid, caller must set buffer_std to indicate whether the
|
|
* page uses standard pd_lower/pd_upper header fields. If this is true, then
|
|
* XLOG is allowed to omit the free space between pd_lower and pd_upper from
|
|
* the backed-up page image. Note that even when buffer_std is false, the
|
|
* page MUST have an LSN field as its first eight bytes!
|
|
*
|
|
* Note: data can be NULL to indicate no rmgr data associated with this chain
|
|
* entry. This can be sensible (ie, not a wasted entry) if buffer is valid.
|
|
* The implication is that the buffer has been changed by the operation being
|
|
* logged, and so may need to be backed up, but the change can be redone using
|
|
* only information already present elsewhere in the XLOG entry.
|
|
*/
|
|
typedef struct XLogRecData
|
|
{
|
|
char *data; /* start of rmgr data to include */
|
|
uint32 len; /* length of rmgr data to include */
|
|
Buffer buffer; /* buffer associated with data, if any */
|
|
bool buffer_std; /* buffer has standard pd_lower/pd_upper */
|
|
struct XLogRecData *next; /* next struct in chain, or NULL */
|
|
} XLogRecData;
|
|
|
|
extern TimeLineID ThisTimeLineID; /* current TLI */
|
|
extern bool InRecovery;
|
|
extern XLogRecPtr XactLastRecEnd;
|
|
|
|
/* these variables are GUC parameters related to XLOG */
|
|
extern int CheckPointSegments;
|
|
extern int XLOGbuffers;
|
|
extern bool XLogArchiveMode;
|
|
extern char *XLogArchiveCommand;
|
|
extern int XLogArchiveTimeout;
|
|
extern char *XLOG_sync_method;
|
|
extern const char XLOG_sync_method_default[];
|
|
extern bool log_checkpoints;
|
|
|
|
#define XLogArchivingActive() (XLogArchiveMode)
|
|
#define XLogArchiveCommandSet() (XLogArchiveCommand[0] != '\0')
|
|
|
|
#ifdef WAL_DEBUG
|
|
extern bool XLOG_DEBUG;
|
|
#endif
|
|
|
|
/*
|
|
* OR-able request flag bits for checkpoints. The "cause" bits are used only
|
|
* for logging purposes. Note: the flags must be defined so that it's
|
|
* sensible to OR together request flags arising from different requestors.
|
|
*/
|
|
|
|
/* These directly affect the behavior of CreateCheckPoint and subsidiaries */
|
|
#define CHECKPOINT_IS_SHUTDOWN 0x0001 /* Checkpoint is for shutdown */
|
|
#define CHECKPOINT_IMMEDIATE 0x0002 /* Do it without delays */
|
|
#define CHECKPOINT_FORCE 0x0004 /* Force even if no activity */
|
|
/* These are important to RequestCheckpoint */
|
|
#define CHECKPOINT_WAIT 0x0008 /* Wait for completion */
|
|
/* These indicate the cause of a checkpoint request */
|
|
#define CHECKPOINT_CAUSE_XLOG 0x0010 /* XLOG consumption */
|
|
#define CHECKPOINT_CAUSE_TIME 0x0020 /* Elapsed time */
|
|
|
|
/* Checkpoint statistics */
|
|
typedef struct CheckpointStatsData
|
|
{
|
|
TimestampTz ckpt_start_t; /* start of checkpoint */
|
|
TimestampTz ckpt_write_t; /* start of flushing buffers */
|
|
TimestampTz ckpt_sync_t; /* start of fsyncs */
|
|
TimestampTz ckpt_sync_end_t; /* end of fsyncs */
|
|
TimestampTz ckpt_end_t; /* end of checkpoint */
|
|
|
|
int ckpt_bufs_written; /* # of buffers written */
|
|
|
|
int ckpt_segs_added; /* # of new xlog segments created */
|
|
int ckpt_segs_removed; /* # of xlog segments deleted */
|
|
int ckpt_segs_recycled; /* # of xlog segments recycled */
|
|
} CheckpointStatsData;
|
|
|
|
extern CheckpointStatsData CheckpointStats;
|
|
|
|
|
|
extern XLogRecPtr XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata);
|
|
extern void XLogFlush(XLogRecPtr RecPtr);
|
|
extern void XLogBackgroundFlush(void);
|
|
extern void XLogAsyncCommitFlush(void);
|
|
extern bool XLogNeedsFlush(XLogRecPtr RecPtr);
|
|
|
|
extern void XLogSetAsyncCommitLSN(XLogRecPtr record);
|
|
|
|
extern void xlog_redo(XLogRecPtr lsn, XLogRecord *record);
|
|
extern void xlog_desc(StringInfo buf, uint8 xl_info, char *rec);
|
|
|
|
extern void UpdateControlFile(void);
|
|
extern Size XLOGShmemSize(void);
|
|
extern void XLOGShmemInit(void);
|
|
extern void BootStrapXLOG(void);
|
|
extern void StartupXLOG(void);
|
|
extern void ShutdownXLOG(int code, Datum arg);
|
|
extern void InitXLOGAccess(void);
|
|
extern void CreateCheckPoint(int flags);
|
|
extern void XLogPutNextOid(Oid nextOid);
|
|
extern XLogRecPtr GetRedoRecPtr(void);
|
|
extern XLogRecPtr GetInsertRecPtr(void);
|
|
extern void GetNextXidAndEpoch(TransactionId *xid, uint32 *epoch);
|
|
|
|
#endif /* XLOG_H */
|