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/*
* xlogutils.h
*
* Utilities for replaying WAL records.
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/access/xlogutils.h
*/
#ifndef XLOG_UTILS_H
#define XLOG_UTILS_H
#include "access/xlogreader.h"
#include "storage/bufmgr.h"
/*
* Prior to 8.4, all activity during recovery was carried out by the startup
* process. This local variable continues to be used in many parts of the
* code to indicate actions taken by RecoveryManagers. Other processes that
* potentially perform work during recovery should check RecoveryInProgress().
* See XLogCtl notes in xlog.c.
*/
extern __thread PGDLLIMPORT bool InRecovery;
/*
* Like InRecovery, standbyState is only valid in the startup process.
* In all other processes it will have the value STANDBY_DISABLED (so
* InHotStandby will read as false).
*
* In DISABLED state, we're performing crash recovery or hot standby was
* disabled in postgresql.conf.
*
* In INITIALIZED state, we've run InitRecoveryTransactionEnvironment, but
* we haven't yet processed a RUNNING_XACTS or shutdown-checkpoint WAL record
* to initialize our primary-transaction tracking system.
*
* When the transaction tracking is initialized, we enter the SNAPSHOT_PENDING
* state. The tracked information might still be incomplete, so we can't allow
* connections yet, but redo functions must update the in-memory state when
* appropriate.
*
* In SNAPSHOT_READY mode, we have full knowledge of transactions that are
* (or were) running on the primary at the current WAL location. Snapshots
* can be taken, and read-only queries can be run.
*/
typedef enum
{
STANDBY_DISABLED,
STANDBY_INITIALIZED,
STANDBY_SNAPSHOT_PENDING,
STANDBY_SNAPSHOT_READY
} HotStandbyState;
extern __thread PGDLLIMPORT HotStandbyState standbyState;
#define InHotStandby (standbyState >= STANDBY_SNAPSHOT_PENDING)
extern bool XLogHaveInvalidPages(void);
extern void XLogCheckInvalidPages(void);
extern void XLogDropRelation(RelFileLocator rlocator, ForkNumber forknum);
extern void XLogDropDatabase(Oid dbid);
extern void XLogTruncateRelation(RelFileLocator rlocator, ForkNumber forkNum,
BlockNumber nblocks);
/* Result codes for XLogReadBufferForRedo[Extended] */
typedef enum
{
BLK_NEEDS_REDO, /* changes from WAL record need to be applied */
BLK_DONE, /* block is already up-to-date */
BLK_RESTORED, /* block was restored from a full-page image */
BLK_NOTFOUND /* block was not found (and hence does not
* need to be replayed) */
} XLogRedoAction;
/* Private data of the read_local_xlog_page_no_wait callback. */
typedef struct ReadLocalXLogPageNoWaitPrivate
{
bool end_of_wal; /* true, when end of WAL is reached */
} ReadLocalXLogPageNoWaitPrivate;
extern XLogRedoAction XLogReadBufferForRedo(XLogReaderState *record,
uint8 block_id, Buffer *buf);
extern Buffer XLogInitBufferForRedo(XLogReaderState *record, uint8 block_id);
extern XLogRedoAction XLogReadBufferForRedoExtended(XLogReaderState *record,
uint8 block_id,
ReadBufferMode mode, bool get_cleanup_lock,
Buffer *buf);
extern Buffer XLogReadBufferExtended(RelFileLocator rlocator, ForkNumber forknum,
BlockNumber blkno, ReadBufferMode mode,
Buffer recent_buffer);
extern Relation CreateFakeRelcacheEntry(RelFileLocator rlocator);
extern void FreeFakeRelcacheEntry(Relation fakerel);
extern int read_local_xlog_page(XLogReaderState *state,
XLogRecPtr targetPagePtr, int reqLen,
XLogRecPtr targetRecPtr, char *cur_page);
extern int read_local_xlog_page_no_wait(XLogReaderState *state,
XLogRecPtr targetPagePtr, int reqLen,
XLogRecPtr targetRecPtr,
char *cur_page);
extern void wal_segment_open(XLogReaderState *state,
XLogSegNo nextSegNo,
TimeLineID *tli_p);
extern void wal_segment_close(XLogReaderState *state);
extern void XLogReadDetermineTimeline(XLogReaderState *state,
XLogRecPtr wantPage,
uint32 wantLength,
TimeLineID currTLI);
extern void WALReadRaiseError(WALReadError *errinfo);
#endif
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