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/*
* xlog.h
*
* PostgreSQL transaction log manager
*
* Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/access/xlog.h
*/
#ifndef XLOG_H
#define XLOG_H
#include "access/rmgr.h"
#include "access/xlogdefs.h"
#include "datatype/timestamp.h"
#include "lib/stringinfo.h"
#include "storage/buf.h"
#include "utils/pg_crc.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 four 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 4 disk blocks per XLOG
* record.
*/
#define XLR_BKP_BLOCK_MASK 0x0F /* all info bits used for bkp blocks */
#define XLR_MAX_BKP_BLOCKS 4
#define XLR_BKP_BLOCK(iblk) (0x08 >> (iblk)) /* iblk in 0..3 */
/* These macros are deprecated and will be removed in 9.3; use XLR_BKP_BLOCK */
#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 */
#define XLR_BKP_BLOCK_4 XLR_SET_BKP_BLOCK(3) /* 0x01 */
/* Sync methods */
#define SYNC_METHOD_FSYNC 0
#define SYNC_METHOD_FDATASYNC 1
#define SYNC_METHOD_OPEN 2 /* for O_SYNC */
#define SYNC_METHOD_FSYNC_WRITETHROUGH 3
#define SYNC_METHOD_OPEN_DSYNC 4 /* for O_DSYNC */
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(N) 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(N) to know what is actually stored in the XLOG record.
* The N'th XLR_BKP_BLOCK bit corresponds to the N'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 PGDLLIMPORT TimeLineID ThisTimeLineID; /* current TLI */
/*
* 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 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 master-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 in the master 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 HotStandbyState standbyState;
#define InHotStandby (standbyState >= STANDBY_SNAPSHOT_PENDING)
/*
* Recovery target type.
* Only set during a Point in Time recovery, not when standby_mode = on
*/
typedef enum
{
RECOVERY_TARGET_UNSET,
RECOVERY_TARGET_XID,
RECOVERY_TARGET_TIME,
RECOVERY_TARGET_NAME
} RecoveryTargetType;
extern XLogRecPtr XactLastRecEnd;
extern bool reachedConsistency;
/* these variables are GUC parameters related to XLOG */
extern int CheckPointSegments;
extern int wal_keep_segments;
extern int XLOGbuffers;
extern int XLogArchiveTimeout;
extern bool XLogArchiveMode;
extern char *XLogArchiveCommand;
extern bool EnableHotStandby;
extern bool fullPageWrites;
extern bool log_checkpoints;
/* WAL levels */
typedef enum WalLevel
{
WAL_LEVEL_MINIMAL = 0,
WAL_LEVEL_ARCHIVE,
WAL_LEVEL_HOT_STANDBY
} WalLevel;
extern int wal_level;
#define XLogArchivingActive() (XLogArchiveMode && wal_level >= WAL_LEVEL_ARCHIVE)
#define XLogArchiveCommandSet() (XLogArchiveCommand[0] != '\0')
/*
* Is WAL-logging necessary for archival or log-shipping, or can we skip
* WAL-logging if we fsync() the data before committing instead?
*/
#define XLogIsNeeded() (wal_level >= WAL_LEVEL_ARCHIVE)
/* Do we need to WAL-log information required only for Hot Standby? */
#define XLogStandbyInfoActive() (wal_level >= WAL_LEVEL_HOT_STANDBY)
#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_END_OF_RECOVERY 0x0002 /* Like shutdown checkpoint,
* but issued at end of WAL
* recovery */
#define CHECKPOINT_IMMEDIATE 0x0004 /* Do it without delays */
#define CHECKPOINT_FORCE 0x0008 /* Force even if no activity */
/* These are important to RequestCheckpoint */
#define CHECKPOINT_WAIT 0x0010 /* Wait for completion */
/* These indicate the cause of a checkpoint request */
#define CHECKPOINT_CAUSE_XLOG 0x0020 /* XLOG consumption */
#define CHECKPOINT_CAUSE_TIME 0x0040 /* Elapsed time */
#define CHECKPOINT_FLUSH_ALL 0x0080 /* Flush all pages, including those
* belonging to unlogged tables */
/* 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 */
int ckpt_sync_rels; /* # of relations synced */
uint64 ckpt_longest_sync; /* Longest sync for one relation */
uint64 ckpt_agg_sync_time; /* The sum of all the individual sync
* times, which is not necessarily the
* same as the total elapsed time for
* the entire sync phase. */
} CheckpointStatsData;
extern CheckpointStatsData CheckpointStats;
extern XLogRecPtr XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata);
extern void XLogFlush(XLogRecPtr RecPtr);
extern bool XLogBackgroundFlush(void);
extern bool XLogNeedsFlush(XLogRecPtr RecPtr);
extern int XLogFileInit(uint32 log, uint32 seg,
bool *use_existent, bool use_lock);
extern int XLogFileOpen(uint32 log, uint32 seg);
extern void CheckXLogRemoved(uint32 log, uint32 seg, TimeLineID tli);
extern void XLogSetAsyncXactLSN(XLogRecPtr record);
extern Buffer RestoreBackupBlock(XLogRecPtr lsn, XLogRecord *record,
int block_index,
bool get_cleanup_lock, bool keep_buffer);
extern void xlog_redo(XLogRecPtr lsn, XLogRecord *record);
extern void xlog_desc(StringInfo buf, uint8 xl_info, char *rec);
extern void issue_xlog_fsync(int fd, uint32 log, uint32 seg);
extern bool RecoveryInProgress(void);
extern bool HotStandbyActive(void);
extern bool HotStandbyActiveInReplay(void);
extern bool XLogInsertAllowed(void);
extern void GetXLogReceiptTime(TimestampTz *rtime, bool *fromStream);
extern XLogRecPtr GetXLogReplayRecPtr(TimeLineID *targetTLI);
extern XLogRecPtr GetStandbyFlushRecPtr(TimeLineID *targetTLI);
extern XLogRecPtr GetXLogInsertRecPtr(void);
extern XLogRecPtr GetXLogWriteRecPtr(void);
extern bool RecoveryIsPaused(void);
extern void SetRecoveryPause(bool recoveryPause);
extern TimestampTz GetLatestXTime(void);
extern TimestampTz GetCurrentChunkReplayStartTime(void);
extern void UpdateControlFile(void);
extern uint64 GetSystemIdentifier(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 bool CreateRestartPoint(int flags);
extern void XLogPutNextOid(Oid nextOid);
extern XLogRecPtr XLogRestorePoint(const char *rpName);
extern void UpdateFullPageWrites(void);
extern XLogRecPtr GetRedoRecPtr(void);
extern XLogRecPtr GetInsertRecPtr(void);
extern XLogRecPtr GetFlushRecPtr(void);
extern void GetNextXidAndEpoch(TransactionId *xid, uint32 *epoch);
extern TimeLineID GetRecoveryTargetTLI(void);
extern void RemovePromoteSignalFiles(void);
extern bool CheckPromoteSignal(void);
extern void WakeupRecovery(void);
extern void SetWalWriterSleeping(bool sleeping);
/*
* Starting/stopping a base backup
*/
extern XLogRecPtr do_pg_start_backup(const char *backupidstr, bool fast, char **labelfile);
extern XLogRecPtr do_pg_stop_backup(char *labelfile, bool waitforarchive);
extern void do_pg_abort_backup(void);
/* File path names (all relative to $PGDATA) */
#define BACKUP_LABEL_FILE "backup_label"
#define BACKUP_LABEL_OLD "backup_label.old"
#endif /* XLOG_H */
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