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/*
* xlog.h
*
* PostgreSQL transaction log manager
*
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.60 2005/04/28 21:47:17 tgl Exp $
*/
#ifndef XLOG_H
#define XLOG_H
#include "access/rmgr.h"
#include "access/transam.h"
#include "access/xlogdefs.h"
#include "storage/buf.h"
#include "utils/pg_crc.h"
/*
* Header for each record in XLOG
*
* NOTE: xl_len counts only the rmgr data, not the XLogRecord header,
* and also not any backup blocks appended to the record (which are signaled
* by xl_info flag bits). The total space needed for an XLOG record is
* really:
*
* SizeOfXLogRecord + xl_len + n_backup_blocks * (sizeof(BkpBlock) + BLCKSZ)
*
* rounded up to a MAXALIGN boundary (so that all xlog records start on
* MAXALIGN boundaries).
*/
typedef struct XLogRecord
{
crc64 xl_crc; /* CRC for this record */
XLogRecPtr xl_prev; /* ptr to previous record in log */
TransactionId xl_xid; /* xact id */
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. (Could support 4 if we cared to dedicate all the xl_info bits for
* this purpose; currently bit 0 of xl_info is unused and available.)
*/
#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 */
/*
* Sometimes we log records which are out of transaction control.
* Rmgr may "or" XLOG_NO_TRAN into info passed to XLogInsert to indicate this.
*/
#define XLOG_NO_TRAN XLR_INFO_MASK
/*
* List of these structs is used to pass data to XLogInsert().
*
* 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 locked while this is going on, so that it won't change under us.
* NB: when this happens, we do not bother to insert the associated data 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.
*/
typedef struct XLogRecData
{
Buffer buffer; /* buffer associated with this data */
char *data;
uint32 len;
struct XLogRecData *next;
} XLogRecData;
extern TimeLineID ThisTimeLineID; /* current TLI */
extern bool InRecovery;
extern XLogRecPtr MyLastRecPtr;
extern bool MyXactMadeXLogEntry;
extern bool MyXactMadeTempRelUpdate;
extern XLogRecPtr ProcLastRecEnd;
/* these variables are GUC parameters related to XLOG */
extern int CheckPointSegments;
extern int XLOGbuffers;
extern char *XLogArchiveCommand;
extern char *XLOG_sync_method;
extern const char XLOG_sync_method_default[];
#define XLogArchivingActive() (XLogArchiveCommand[0] != '\0')
#ifdef WAL_DEBUG
extern bool XLOG_DEBUG;
#endif
extern XLogRecPtr XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata);
extern void XLogFlush(XLogRecPtr RecPtr);
extern void xlog_redo(XLogRecPtr lsn, XLogRecord *record);
extern void xlog_undo(XLogRecPtr lsn, XLogRecord *record);
extern void xlog_desc(char *buf, uint8 xl_info, char *rec);
extern void UpdateControlFile(void);
extern int XLOGShmemSize(void);
extern void XLOGShmemInit(void);
extern void XLOGPathInit(void);
extern void BootStrapXLOG(void);
extern void StartupXLOG(void);
extern void ShutdownXLOG(int code, Datum arg);
extern void InitXLOGAccess(void);
extern void CreateCheckPoint(bool shutdown, bool force);
extern void XLogPutNextOid(Oid nextOid);
extern void XLogPutNextMultiXactId(MultiXactId multi);
extern XLogRecPtr GetRedoRecPtr(void);
#endif /* XLOG_H */
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