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/*------------------------------------------------------------------------- * * transam.h * postgres transaction access method support code * * * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * src/include/access/transam.h * *------------------------------------------------------------------------- */ #ifndef TRANSAM_H #define TRANSAM_H #include "access/xlogdefs.h" /* ---------------- * Special transaction ID values * * BootstrapTransactionId is the XID for "bootstrap" operations, and * FrozenTransactionId is used for very old tuples. Both should * always be considered valid. * * FirstNormalTransactionId is the first "normal" transaction id. * Note: if you need to change it, you must change pg_class.h as well. * ---------------- */ #define InvalidTransactionId ((TransactionId) 0) #define BootstrapTransactionId ((TransactionId) 1) #define FrozenTransactionId ((TransactionId) 2) #define FirstNormalTransactionId ((TransactionId) 3) #define MaxTransactionId ((TransactionId) 0xFFFFFFFF) /* ---------------- * transaction ID manipulation macros * ---------------- */ #define TransactionIdIsValid(xid) ((xid) != InvalidTransactionId) #define TransactionIdIsNormal(xid) ((xid) >= FirstNormalTransactionId) #define TransactionIdEquals(id1, id2) ((id1) == (id2)) #define TransactionIdStore(xid, dest) (*(dest) = (xid)) #define StoreInvalidTransactionId(dest) (*(dest) = InvalidTransactionId) /* advance a transaction ID variable, handling wraparound correctly */ #define TransactionIdAdvance(dest) \ do { \ (dest)++; \ if ((dest) < FirstNormalTransactionId) \ (dest) = FirstNormalTransactionId; \ } while(0) /* back up a transaction ID variable, handling wraparound correctly */ #define TransactionIdRetreat(dest) \ do { \ (dest)--; \ } while ((dest) < FirstNormalTransactionId) /* compare two XIDs already known to be normal; this is a macro for speed */ #define NormalTransactionIdPrecedes(id1, id2) \ (AssertMacro(TransactionIdIsNormal(id1) && TransactionIdIsNormal(id2)), \ (int32) ((id1) - (id2)) < 0) /* ---------- * Object ID (OID) zero is InvalidOid. * * OIDs 1-9999 are reserved for manual assignment (see the files * in src/include/catalog/). * * OIDS 10000-16383 are reserved for assignment during initdb * using the OID generator. (We start the generator at 10000.) * * OIDs beginning at 16384 are assigned from the OID generator * during normal multiuser operation. (We force the generator up to * 16384 as soon as we are in normal operation.) * * The choices of 10000 and 16384 are completely arbitrary, and can be moved * if we run low on OIDs in either category. Changing the macros below * should be sufficient to do this. * * NOTE: if the OID generator wraps around, we skip over OIDs 0-16383 * and resume with 16384. This minimizes the odds of OID conflict, by not * reassigning OIDs that might have been assigned during initdb. * ---------- */ #define FirstBootstrapObjectId 10000 #define FirstNormalObjectId 16384 /* * VariableCache is a data structure in shared memory that is used to track * OID and XID assignment state. For largely historical reasons, there is * just one struct with different fields that are protected by different * LWLocks. * * Note: xidWrapLimit and oldestXidDB are not "active" values, but are * used just to generate useful messages when xidWarnLimit or xidStopLimit * are exceeded. */ typedef struct VariableCacheData { /* * These fields are protected by OidGenLock. */ Oid nextOid; /* next OID to assign */ uint32 oidCount; /* OIDs available before must do XLOG work */ /* * These fields are protected by XidGenLock. */ TransactionId nextXid; /* next XID to assign */ TransactionId oldestXid; /* cluster-wide minimum datfrozenxid */ TransactionId xidVacLimit; /* start forcing autovacuums here */ TransactionId xidWarnLimit; /* start complaining here */ TransactionId xidStopLimit; /* refuse to advance nextXid beyond here */ TransactionId xidWrapLimit; /* where the world ends */ Oid oldestXidDB; /* database with minimum datfrozenxid */ /* * These fields are protected by ProcArrayLock. */ TransactionId latestCompletedXid; /* newest XID that has committed or * aborted */ } VariableCacheData; typedef VariableCacheData *VariableCache; /* ---------------- * extern declarations * ---------------- */ /* in transam/xact.c */ extern bool TransactionStartedDuringRecovery(void); /* in transam/varsup.c */ extern PGDLLIMPORT VariableCache ShmemVariableCache; /* in transam/transam.c */ extern const XLogRecPtr InvalidXLogRecPtr; /* * prototypes for functions in transam/transam.c */ extern bool TransactionIdDidCommit(TransactionId transactionId); extern bool TransactionIdDidAbort(TransactionId transactionId); extern bool TransactionIdIsKnownCompleted(TransactionId transactionId); extern void TransactionIdAbort(TransactionId transactionId); extern void TransactionIdCommitTree(TransactionId xid, int nxids, TransactionId *xids); extern void TransactionIdAsyncCommitTree(TransactionId xid, int nxids, TransactionId *xids, XLogRecPtr lsn); extern void TransactionIdAbortTree(TransactionId xid, int nxids, TransactionId *xids); extern bool TransactionIdPrecedes(TransactionId id1, TransactionId id2); extern bool TransactionIdPrecedesOrEquals(TransactionId id1, TransactionId id2); extern bool TransactionIdFollows(TransactionId id1, TransactionId id2); extern bool TransactionIdFollowsOrEquals(TransactionId id1, TransactionId id2); extern TransactionId TransactionIdLatest(TransactionId mainxid, int nxids, const TransactionId *xids); extern XLogRecPtr TransactionIdGetCommitLSN(TransactionId xid); /* in transam/varsup.c */ extern TransactionId GetNewTransactionId(bool isSubXact); extern TransactionId ReadNewTransactionId(void); extern void SetTransactionIdLimit(TransactionId oldest_datfrozenxid, Oid oldest_datoid); extern bool ForceTransactionIdLimitUpdate(void); extern Oid GetNewObjectId(void); #endif /* TRAMSAM_H */