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/*
* xlog_internal.h
*
* PostgreSQL write-ahead log internal declarations
*
* NOTE: this file is intended to contain declarations useful for
* manipulating the XLOG files directly, but it is not supposed to be
* needed by rmgr routines (redo support for individual record types).
* So the XLogRecord typedef and associated stuff appear in xlogrecord.h.
*
* Note: This file must be includable in both frontend and backend contexts,
* to allow stand-alone tools like pg_receivewal to deal with WAL files.
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/access/xlog_internal.h
*/
#ifndef XLOG_INTERNAL_H
#define XLOG_INTERNAL_H
#include "access/xlogdefs.h"
#include "access/xlogreader.h"
#include "datatype/timestamp.h"
#include "lib/stringinfo.h"
#include "pgtime.h"
#include "storage/block.h"
#include "storage/relfilelocator.h"
/*
* Each page of XLOG file has a header like this:
*/
#define XLOG_PAGE_MAGIC 0xD113 /* can be used as WAL version indicator */
typedef struct XLogPageHeaderData
{
uint16 xlp_magic; /* magic value for correctness checks */
uint16 xlp_info; /* flag bits, see below */
TimeLineID xlp_tli; /* TimeLineID of first record on page */
XLogRecPtr xlp_pageaddr; /* XLOG address of this page */
/*
* When there is not enough space on current page for whole record, we
* continue on the next page. xlp_rem_len is the number of bytes
* remaining from a previous page; it tracks xl_tot_len in the initial
* header. Note that the continuation data isn't necessarily aligned.
*/
uint32 xlp_rem_len; /* total len of remaining data for record */
} XLogPageHeaderData;
#define SizeOfXLogShortPHD MAXALIGN(sizeof(XLogPageHeaderData))
typedef XLogPageHeaderData *XLogPageHeader;
/*
* When the XLP_LONG_HEADER flag is set, we store additional fields in the
* page header. (This is ordinarily done just in the first page of an
* XLOG file.) The additional fields serve to identify the file accurately.
*/
typedef struct XLogLongPageHeaderData
{
XLogPageHeaderData std; /* standard header fields */
uint64 xlp_sysid; /* system identifier from pg_control */
uint32 xlp_seg_size; /* just as a cross-check */
uint32 xlp_xlog_blcksz; /* just as a cross-check */
} XLogLongPageHeaderData;
#define SizeOfXLogLongPHD MAXALIGN(sizeof(XLogLongPageHeaderData))
typedef XLogLongPageHeaderData *XLogLongPageHeader;
/* When record crosses page boundary, set this flag in new page's header */
#define XLP_FIRST_IS_CONTRECORD 0x0001
/* This flag indicates a "long" page header */
#define XLP_LONG_HEADER 0x0002
/* This flag indicates backup blocks starting in this page are optional */
#define XLP_BKP_REMOVABLE 0x0004
/* Replaces a missing contrecord; see CreateOverwriteContrecordRecord */
#define XLP_FIRST_IS_OVERWRITE_CONTRECORD 0x0008
/* All defined flag bits in xlp_info (used for validity checking of header) */
#define XLP_ALL_FLAGS 0x000F
#define XLogPageHeaderSize(hdr) \
(((hdr)->xlp_info & XLP_LONG_HEADER) ? SizeOfXLogLongPHD : SizeOfXLogShortPHD)
/* wal_segment_size can range from 1MB to 1GB */
#define WalSegMinSize 1024 * 1024
#define WalSegMaxSize 1024 * 1024 * 1024
/* default number of min and max wal segments */
#define DEFAULT_MIN_WAL_SEGS 5
#define DEFAULT_MAX_WAL_SEGS 64
/* check that the given size is a valid wal_segment_size */
#define IsPowerOf2(x) (x > 0 && ((x) & ((x)-1)) == 0)
#define IsValidWalSegSize(size) \
(IsPowerOf2(size) && \
((size) >= WalSegMinSize && (size) <= WalSegMaxSize))
#define XLogSegmentsPerXLogId(wal_segsz_bytes) \
(UINT64CONST(0x100000000) / (wal_segsz_bytes))
#define XLogSegNoOffsetToRecPtr(segno, offset, wal_segsz_bytes, dest) \
(dest) = (segno) * (wal_segsz_bytes) + (offset)
#define XLogSegmentOffset(xlogptr, wal_segsz_bytes) \
((xlogptr) & ((wal_segsz_bytes) - 1))
/*
* Compute a segment number 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, logSegNo, wal_segsz_bytes) \
logSegNo = (xlrp) / (wal_segsz_bytes)
#define XLByteToPrevSeg(xlrp, logSegNo, wal_segsz_bytes) \
logSegNo = ((xlrp) - 1) / (wal_segsz_bytes)
/*
* Convert values of GUCs measured in megabytes to equiv. segment count.
* Rounds down.
*/
#define XLogMBVarToSegs(mbvar, wal_segsz_bytes) \
((mbvar) / ((wal_segsz_bytes) / (1024 * 1024)))
/*
* 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, logSegNo, wal_segsz_bytes) \
(((xlrp) / (wal_segsz_bytes)) == (logSegNo))
#define XLByteInPrevSeg(xlrp, logSegNo, wal_segsz_bytes) \
((((xlrp) - 1) / (wal_segsz_bytes)) == (logSegNo))
/* Check if an XLogRecPtr value is in a plausible range */
#define XRecOffIsValid(xlrp) \
((xlrp) % XLOG_BLCKSZ >= SizeOfXLogShortPHD)
/*
* The XLog directory and control file (relative to $PGDATA)
*/
#define XLOGDIR "pg_wal"
#define XLOG_CONTROL_FILE "global/pg_control"
/*
* These macros encapsulate knowledge about the exact layout of XLog file
* names, timeline history file names, and archive-status file names.
*/
#define MAXFNAMELEN 64
/* Length of XLog file name */
#define XLOG_FNAME_LEN 24
/*
* Generate a WAL segment file name. Do not use this function in a helper
* function allocating the result generated.
*/
static inline void
XLogFileName(char *fname, TimeLineID tli, XLogSegNo logSegNo, int wal_segsz_bytes)
{
snprintf(fname, MAXFNAMELEN, "%08X%08X%08X", tli,
(uint32) (logSegNo / XLogSegmentsPerXLogId(wal_segsz_bytes)),
(uint32) (logSegNo % XLogSegmentsPerXLogId(wal_segsz_bytes)));
}
static inline void
XLogFileNameById(char *fname, TimeLineID tli, uint32 log, uint32 seg)
{
snprintf(fname, MAXFNAMELEN, "%08X%08X%08X", tli, log, seg);
}
static inline bool
IsXLogFileName(const char *fname)
{
return (strlen(fname) == XLOG_FNAME_LEN && \
strspn(fname, "0123456789ABCDEF") == XLOG_FNAME_LEN);
}
/*
* XLOG segment with .partial suffix. Used by pg_receivewal and at end of
* archive recovery, when we want to archive a WAL segment but it might not
* be complete yet.
*/
static inline bool
IsPartialXLogFileName(const char *fname)
{
return (strlen(fname) == XLOG_FNAME_LEN + strlen(".partial") &&
strspn(fname, "0123456789ABCDEF") == XLOG_FNAME_LEN &&
strcmp(fname + XLOG_FNAME_LEN, ".partial") == 0);
}
static inline void
XLogFromFileName(const char *fname, TimeLineID *tli, XLogSegNo *logSegNo, int wal_segsz_bytes)
{
uint32 log;
uint32 seg;
sscanf(fname, "%08X%08X%08X", tli, &log, &seg);
*logSegNo = (uint64) log * XLogSegmentsPerXLogId(wal_segsz_bytes) + seg;
}
static inline void
XLogFilePath(char *path, TimeLineID tli, XLogSegNo logSegNo, int wal_segsz_bytes)
{
snprintf(path, MAXPGPATH, XLOGDIR "/%08X%08X%08X", tli,
(uint32) (logSegNo / XLogSegmentsPerXLogId(wal_segsz_bytes)),
(uint32) (logSegNo % XLogSegmentsPerXLogId(wal_segsz_bytes)));
}
static inline void
TLHistoryFileName(char *fname, TimeLineID tli)
{
snprintf(fname, MAXFNAMELEN, "%08X.history", tli);
}
static inline bool
IsTLHistoryFileName(const char *fname)
{
return (strlen(fname) == 8 + strlen(".history") &&
strspn(fname, "0123456789ABCDEF") == 8 &&
strcmp(fname + 8, ".history") == 0);
}
static inline void
TLHistoryFilePath(char *path, TimeLineID tli)
{
snprintf(path, MAXPGPATH, XLOGDIR "/%08X.history", tli);
}
static inline void
StatusFilePath(char *path, const char *xlog, const char *suffix)
{
snprintf(path, MAXPGPATH, XLOGDIR "/archive_status/%s%s", xlog, suffix);
}
static inline void
BackupHistoryFileName(char *fname, TimeLineID tli, XLogSegNo logSegNo, XLogRecPtr startpoint, int wal_segsz_bytes)
{
snprintf(fname, MAXFNAMELEN, "%08X%08X%08X.%08X.backup", tli,
(uint32) (logSegNo / XLogSegmentsPerXLogId(wal_segsz_bytes)),
(uint32) (logSegNo % XLogSegmentsPerXLogId(wal_segsz_bytes)),
(uint32) (XLogSegmentOffset(startpoint, wal_segsz_bytes)));
}
static inline bool
IsBackupHistoryFileName(const char *fname)
{
return (strlen(fname) > XLOG_FNAME_LEN &&
strspn(fname, "0123456789ABCDEF") == XLOG_FNAME_LEN &&
strcmp(fname + strlen(fname) - strlen(".backup"), ".backup") == 0);
}
static inline void
BackupHistoryFilePath(char *path, TimeLineID tli, XLogSegNo logSegNo, XLogRecPtr startpoint, int wal_segsz_bytes)
{
snprintf(path, MAXPGPATH, XLOGDIR "/%08X%08X%08X.%08X.backup", tli,
(uint32) (logSegNo / XLogSegmentsPerXLogId(wal_segsz_bytes)),
(uint32) (logSegNo % XLogSegmentsPerXLogId(wal_segsz_bytes)),
(uint32) (XLogSegmentOffset((startpoint), wal_segsz_bytes)));
}
/*
* Information logged when we detect a change in one of the parameters
* important for Hot Standby.
*/
typedef struct xl_parameter_change
{
int MaxConnections;
int max_worker_processes;
int max_wal_senders;
int max_prepared_xacts;
int max_locks_per_xact;
int wal_level;
bool wal_log_hints;
bool track_commit_timestamp;
} xl_parameter_change;
/* logs restore point */
typedef struct xl_restore_point
{
TimestampTz rp_time;
char rp_name[MAXFNAMELEN];
} xl_restore_point;
/* Overwrite of prior contrecord */
typedef struct xl_overwrite_contrecord
{
XLogRecPtr overwritten_lsn;
TimestampTz overwrite_time;
} xl_overwrite_contrecord;
/* End of recovery mark, when we don't do an END_OF_RECOVERY checkpoint */
typedef struct xl_end_of_recovery
{
TimestampTz end_time;
TimeLineID ThisTimeLineID; /* new TLI */
TimeLineID PrevTimeLineID; /* previous TLI we forked off from */
} xl_end_of_recovery;
/*
* The functions in xloginsert.c construct a chain of XLogRecData structs
* to represent the final WAL record.
*/
typedef struct XLogRecData
{
struct XLogRecData *next; /* next struct in chain, or NULL */
char *data; /* start of rmgr data to include */
uint32 len; /* length of rmgr data to include */
} XLogRecData;
/*
* Recovery target action.
*/
typedef enum
{
RECOVERY_TARGET_ACTION_PAUSE,
RECOVERY_TARGET_ACTION_PROMOTE,
RECOVERY_TARGET_ACTION_SHUTDOWN
} RecoveryTargetAction;
struct LogicalDecodingContext;
struct XLogRecordBuffer;
/*
* Method table for resource managers.
*
* This struct must be kept in sync with the PG_RMGR definition in
* rmgr.c.
*
* rm_identify must return a name for the record based on xl_info (without
* reference to the rmid). For example, XLOG_BTREE_VACUUM would be named
* "VACUUM". rm_desc can then be called to obtain additional detail for the
* record, if available (e.g. the last block).
*
* rm_mask takes as input a page modified by the resource manager and masks
* out bits that shouldn't be flagged by wal_consistency_checking.
*
* RmgrTable[] is indexed by RmgrId values (see rmgrlist.h). If rm_name is
* NULL, the corresponding RmgrTable entry is considered invalid.
*/
typedef struct RmgrData
{
const char *rm_name;
void (*rm_redo) (XLogReaderState *record);
void (*rm_desc) (StringInfo buf, XLogReaderState *record);
const char *(*rm_identify) (uint8 info);
void (*rm_startup) (void);
void (*rm_cleanup) (void);
void (*rm_mask) (char *pagedata, BlockNumber blkno);
void (*rm_decode) (struct LogicalDecodingContext *ctx,
struct XLogRecordBuffer *buf);
} RmgrData;
extern PGDLLIMPORT RmgrData RmgrTable[];
extern void RmgrStartup(void);
extern void RmgrCleanup(void);
extern void RmgrNotFound(RmgrId rmid);
extern void RegisterCustomRmgr(RmgrId rmid, const RmgrData *rmgr);
#ifndef FRONTEND
static inline bool
RmgrIdExists(RmgrId rmid)
{
return RmgrTable[rmid].rm_name != NULL;
}
static inline RmgrData
GetRmgr(RmgrId rmid)
{
if (unlikely(!RmgrIdExists(rmid)))
RmgrNotFound(rmid);
return RmgrTable[rmid];
}
#endif
/*
* Exported to support xlog switching from checkpointer
*/
extern pg_time_t GetLastSegSwitchData(XLogRecPtr *lastSwitchLSN);
extern XLogRecPtr RequestXLogSwitch(bool mark_unimportant);
extern void GetOldestRestartPoint(XLogRecPtr *oldrecptr, TimeLineID *oldtli);
extern void XLogRecGetBlockRefInfo(XLogReaderState *record, bool pretty,
bool detailed_format, StringInfo buf,
uint32 *fpi_len);
/*
* Exported for the functions in timeline.c and xlogarchive.c. Only valid
* in the startup process.
*/
extern PGDLLIMPORT bool ArchiveRecoveryRequested;
extern PGDLLIMPORT bool InArchiveRecovery;
extern PGDLLIMPORT bool StandbyMode;
extern PGDLLIMPORT char *recoveryRestoreCommand;
#endif /* XLOG_INTERNAL_H */