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/*
* multixact.h
*
* PostgreSQL multi-transaction-log manager
*
* Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/access/multixact.h
*/
#ifndef MULTIXACT_H
#define MULTIXACT_H
#include "access/xlog.h"
/*
* The first two MultiXactId values are reserved to store the truncation Xid
* and epoch of the first segment, so we start assigning multixact values from
* 2.
*/
#define InvalidMultiXactId ((MultiXactId) 0)
#define FirstMultiXactId ((MultiXactId) 1)
#define MaxMultiXactId ((MultiXactId) 0xFFFFFFFF)
#define MultiXactIdIsValid(multi) ((multi) != InvalidMultiXactId)
/* Number of SLRU buffers to use for multixact */
#define NUM_MXACTOFFSET_BUFFERS 8
#define NUM_MXACTMEMBER_BUFFERS 16
/*
* Possible multixact lock modes ("status"). The first four modes are for
* tuple locks (FOR KEY SHARE, FOR SHARE, FOR NO KEY UPDATE, FOR UPDATE); the
* next two are used for update and delete modes.
*/
typedef enum
{
MultiXactStatusForKeyShare = 0x00,
MultiXactStatusForShare = 0x01,
MultiXactStatusForNoKeyUpdate = 0x02,
MultiXactStatusForUpdate = 0x03,
/* an update that doesn't touch "key" columns */
MultiXactStatusNoKeyUpdate = 0x04,
/* other updates, and delete */
MultiXactStatusUpdate = 0x05
} MultiXactStatus;
#define MaxMultiXactStatus MultiXactStatusUpdate
typedef struct MultiXactMember
{
TransactionId xid;
MultiXactStatus status;
} MultiXactMember;
/* ----------------
* multixact-related XLOG entries
* ----------------
*/
#define XLOG_MULTIXACT_ZERO_OFF_PAGE 0x00
#define XLOG_MULTIXACT_ZERO_MEM_PAGE 0x10
#define XLOG_MULTIXACT_CREATE_ID 0x20
typedef struct xl_multixact_create
{
MultiXactId mid; /* new MultiXact's ID */
MultiXactOffset moff; /* its starting offset in members file */
int32 nmembers; /* number of member XIDs */
MultiXactMember members[FLEXIBLE_ARRAY_MEMBER];
} xl_multixact_create;
#define SizeOfMultiXactCreate (offsetof(xl_multixact_create, members))
extern MultiXactId MultiXactIdCreate(TransactionId xid1,
MultiXactStatus status1, TransactionId xid2,
MultiXactStatus status2);
extern MultiXactId MultiXactIdExpand(MultiXactId multi, TransactionId xid,
MultiXactStatus status);
extern MultiXactId ReadNextMultiXactId(void);
extern bool MultiXactIdIsRunning(MultiXactId multi);
extern void MultiXactIdSetOldestMember(void);
extern int GetMultiXactIdMembers(MultiXactId multi, MultiXactMember **xids,
bool allow_old);
extern bool MultiXactIdPrecedes(MultiXactId multi1, MultiXactId multi2);
extern void AtEOXact_MultiXact(void);
extern void AtPrepare_MultiXact(void);
extern void PostPrepare_MultiXact(TransactionId xid);
extern Size MultiXactShmemSize(void);
extern void MultiXactShmemInit(void);
extern void BootStrapMultiXact(void);
extern void StartupMultiXact(void);
extern void ShutdownMultiXact(void);
extern void SetMultiXactIdLimit(MultiXactId oldest_datminmxid,
Oid oldest_datoid);
extern void MultiXactGetCheckptMulti(bool is_shutdown,
MultiXactId *nextMulti,
MultiXactOffset *nextMultiOffset,
MultiXactId *oldestMulti,
Oid *oldestMultiDB);
extern void CheckPointMultiXact(void);
extern MultiXactId GetOldestMultiXactId(void);
extern void TruncateMultiXact(MultiXactId cutoff_multi);
extern void MultiXactSetNextMXact(MultiXactId nextMulti,
MultiXactOffset nextMultiOffset);
extern void MultiXactAdvanceNextMXact(MultiXactId minMulti,
MultiXactOffset minMultiOffset);
extern void MultiXactAdvanceOldest(MultiXactId oldestMulti, Oid oldestMultiDB);
extern void multixact_twophase_recover(TransactionId xid, uint16 info,
void *recdata, uint32 len);
extern void multixact_twophase_postcommit(TransactionId xid, uint16 info,
void *recdata, uint32 len);
extern void multixact_twophase_postabort(TransactionId xid, uint16 info,
void *recdata, uint32 len);
extern void multixact_redo(XLogRecPtr lsn, XLogRecord *record);
extern void multixact_desc(StringInfo buf, uint8 xl_info, char *rec);
extern char *mxid_to_string(MultiXactId multi, int nmembers,
MultiXactMember *members);
#endif /* MULTIXACT_H */
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