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/*
* xlog_internal.h
*
* PostgreSQL transaction 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 xlog.h.
*
* Portions Copyright (c) 1996-2012, 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/xlog.h"
#include "fmgr.h"
#include "pgtime.h"
#include "storage/block.h"
#include "storage/relfilenode.h"
/*
* Header info for a backup block appended to an XLOG record.
*
* As a trivial form of data compression, the XLOG code is aware that
* PG data pages usually contain an unused "hole" in the middle, which
* contains only zero bytes. If hole_length > 0 then we have removed
* such a "hole" from the stored data (and it's not counted in the
* XLOG record's CRC, either). Hence, the amount of block data actually
* present following the BkpBlock struct is BLCKSZ - hole_length bytes.
*
* Note that we don't attempt to align either the BkpBlock struct or the
* block's data. So, the struct must be copied to aligned local storage
* before use.
*/
typedef struct BkpBlock
{
RelFileNode node; /* relation containing block */
ForkNumber fork; /* fork within the relation */
BlockNumber block; /* block number */
uint16 hole_offset; /* number of bytes before "hole" */
uint16 hole_length; /* number of bytes in "hole" */
/* ACTUAL BLOCK DATA FOLLOWS AT END OF STRUCT */
} BkpBlock;
/*
* When there is not enough space on current page for whole record, we
* continue on the next page with continuation record. (However, the
* XLogRecord header will never be split across pages; if there's less than
* SizeOfXLogRecord space left at the end of a page, we just waste it.)
*
* Note that xl_rem_len includes backup-block data; that is, it tracks
* xl_tot_len not xl_len in the initial header. Also note that the
* continuation data isn't necessarily aligned.
*/
typedef struct XLogContRecord
{
uint32 xl_rem_len; /* total len of remaining data for record */
/* ACTUAL LOG DATA FOLLOWS AT END OF STRUCT */
} XLogContRecord;
#define SizeOfXLogContRecord sizeof(XLogContRecord)
/*
* Each page of XLOG file has a header like this:
*/
#define XLOG_PAGE_MAGIC 0xD071 /* 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 */
} 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
/* All defined flag bits in xlp_info (used for validity checking of header) */
#define XLP_ALL_FLAGS 0x0007
#define XLogPageHeaderSize(hdr) \
(((hdr)->xlp_info & XLP_LONG_HEADER) ? SizeOfXLogLongPHD : SizeOfXLogShortPHD)
/*
* We break each logical log file (xlogid value) into segment files of the
* size indicated by XLOG_SEG_SIZE. One possible segment at the end of each
* log file is wasted, to ensure that we don't have problems representing
* last-byte-position-plus-1.
*/
#define XLogSegSize ((uint32) XLOG_SEG_SIZE)
#define XLogSegsPerFile (((uint32) 0xffffffff) / XLogSegSize)
#define XLogFileSize (XLogSegsPerFile * XLogSegSize)
/*
* Macros for manipulating XLOG pointers
*/
/* 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)
/* Align a record pointer to next page */
#define NextLogPage(recptr) \
do { \
if ((recptr).xrecoff % XLOG_BLCKSZ != 0) \
(recptr).xrecoff += \
(XLOG_BLCKSZ - (recptr).xrecoff % XLOG_BLCKSZ); \
if ((recptr).xrecoff >= XLogFileSize) \
{ \
((recptr).xlogid)++; \
(recptr).xrecoff = 0; \
} \
} 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. (We can assume xrecoff is not zero, since no valid recptr
* can have that.)
*/
#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))
/* Check if an xrecoff value is in a plausible range */
#define XRecOffIsValid(xrecoff) \
((xrecoff) % XLOG_BLCKSZ >= SizeOfXLogShortPHD && \
(XLOG_BLCKSZ - (xrecoff) % XLOG_BLCKSZ) >= SizeOfXLogRecord)
/*
* The XLog directory and control file (relative to $PGDATA)
*/
#define XLOGDIR "pg_xlog"
#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
#define XLogFileName(fname, tli, log, seg) \
snprintf(fname, MAXFNAMELEN, "%08X%08X%08X", tli, log, seg)
#define XLogFromFileName(fname, tli, log, seg) \
sscanf(fname, "%08X%08X%08X", tli, log, seg)
#define XLogFilePath(path, tli, log, seg) \
snprintf(path, MAXPGPATH, XLOGDIR "/%08X%08X%08X", tli, log, seg)
#define TLHistoryFileName(fname, tli) \
snprintf(fname, MAXFNAMELEN, "%08X.history", tli)
#define TLHistoryFilePath(path, tli) \
snprintf(path, MAXPGPATH, XLOGDIR "/%08X.history", tli)
#define StatusFilePath(path, xlog, suffix) \
snprintf(path, MAXPGPATH, XLOGDIR "/archive_status/%s%s", xlog, suffix)
#define BackupHistoryFileName(fname, tli, log, seg, offset) \
snprintf(fname, MAXFNAMELEN, "%08X%08X%08X.%08X.backup", tli, log, seg, offset)
#define BackupHistoryFilePath(path, tli, log, seg, offset) \
snprintf(path, MAXPGPATH, XLOGDIR "/%08X%08X%08X.%08X.backup", tli, log, seg, offset)
/*
* Method table for resource managers.
*
* RmgrTable[] is indexed by RmgrId values (see rmgr.h).
*/
typedef struct RmgrData
{
const char *rm_name;
void (*rm_redo) (XLogRecPtr lsn, XLogRecord *rptr);
void (*rm_desc) (StringInfo buf, uint8 xl_info, char *rec);
void (*rm_startup) (void);
void (*rm_cleanup) (void);
bool (*rm_safe_restartpoint) (void);
} RmgrData;
extern const RmgrData RmgrTable[];
/*
* Exported to support xlog switching from checkpointer
*/
extern pg_time_t GetLastSegSwitchTime(void);
extern XLogRecPtr RequestXLogSwitch(void);
/*
* Exported to support xlog archive status setting from WALReceiver
*/
extern void XLogArchiveForceDone(const char *xlog);
/*
* These aren't in xlog.h because I'd rather not include fmgr.h there.
*/
extern Datum pg_start_backup(PG_FUNCTION_ARGS);
extern Datum pg_stop_backup(PG_FUNCTION_ARGS);
extern Datum pg_switch_xlog(PG_FUNCTION_ARGS);
extern Datum pg_create_restore_point(PG_FUNCTION_ARGS);
extern Datum pg_current_xlog_location(PG_FUNCTION_ARGS);
extern Datum pg_current_xlog_insert_location(PG_FUNCTION_ARGS);
extern Datum pg_last_xlog_receive_location(PG_FUNCTION_ARGS);
extern Datum pg_last_xlog_replay_location(PG_FUNCTION_ARGS);
extern Datum pg_last_xact_replay_timestamp(PG_FUNCTION_ARGS);
extern Datum pg_xlogfile_name_offset(PG_FUNCTION_ARGS);
extern Datum pg_xlogfile_name(PG_FUNCTION_ARGS);
extern Datum pg_is_in_recovery(PG_FUNCTION_ARGS);
extern Datum pg_xlog_replay_pause(PG_FUNCTION_ARGS);
extern Datum pg_xlog_replay_resume(PG_FUNCTION_ARGS);
extern Datum pg_is_xlog_replay_paused(PG_FUNCTION_ARGS);
extern Datum pg_xlog_location_diff(PG_FUNCTION_ARGS);
#endif /* XLOG_INTERNAL_H */
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