180 lines
6.3 KiB
C
180 lines
6.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* transam.h
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* postgres transaction access method support code
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*
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*
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* Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/access/transam.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef TRANSAM_H
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#define TRANSAM_H
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#include "access/xlogdefs.h"
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/* ----------------
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* Special transaction ID values
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*
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* BootstrapTransactionId is the XID for "bootstrap" operations, and
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* FrozenTransactionId is used for very old tuples. Both should
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* always be considered valid.
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*
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* FirstNormalTransactionId is the first "normal" transaction id.
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* Note: if you need to change it, you must change pg_class.h as well.
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* ----------------
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*/
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#define InvalidTransactionId ((TransactionId) 0)
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#define BootstrapTransactionId ((TransactionId) 1)
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#define FrozenTransactionId ((TransactionId) 2)
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#define FirstNormalTransactionId ((TransactionId) 3)
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#define MaxTransactionId ((TransactionId) 0xFFFFFFFF)
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/* ----------------
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* transaction ID manipulation macros
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* ----------------
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*/
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#define TransactionIdIsValid(xid) ((xid) != InvalidTransactionId)
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#define TransactionIdIsNormal(xid) ((xid) >= FirstNormalTransactionId)
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#define TransactionIdEquals(id1, id2) ((id1) == (id2))
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#define TransactionIdStore(xid, dest) (*(dest) = (xid))
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#define StoreInvalidTransactionId(dest) (*(dest) = InvalidTransactionId)
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/* advance a transaction ID variable, handling wraparound correctly */
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#define TransactionIdAdvance(dest) \
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do { \
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(dest)++; \
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if ((dest) < FirstNormalTransactionId) \
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(dest) = FirstNormalTransactionId; \
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} while(0)
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/* back up a transaction ID variable, handling wraparound correctly */
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#define TransactionIdRetreat(dest) \
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do { \
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(dest)--; \
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} while ((dest) < FirstNormalTransactionId)
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/* compare two XIDs already known to be normal; this is a macro for speed */
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#define NormalTransactionIdPrecedes(id1, id2) \
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(AssertMacro(TransactionIdIsNormal(id1) && TransactionIdIsNormal(id2)), \
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(int32) ((id1) - (id2)) < 0)
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/* compare two XIDs already known to be normal; this is a macro for speed */
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#define NormalTransactionIdFollows(id1, id2) \
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(AssertMacro(TransactionIdIsNormal(id1) && TransactionIdIsNormal(id2)), \
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(int32) ((id1) - (id2)) > 0)
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/* ----------
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* Object ID (OID) zero is InvalidOid.
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*
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* OIDs 1-9999 are reserved for manual assignment (see the files
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* in src/include/catalog/).
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*
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* OIDS 10000-16383 are reserved for assignment during initdb
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* using the OID generator. (We start the generator at 10000.)
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*
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* OIDs beginning at 16384 are assigned from the OID generator
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* during normal multiuser operation. (We force the generator up to
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* 16384 as soon as we are in normal operation.)
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*
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* The choices of 10000 and 16384 are completely arbitrary, and can be moved
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* if we run low on OIDs in either category. Changing the macros below
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* should be sufficient to do this.
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*
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* NOTE: if the OID generator wraps around, we skip over OIDs 0-16383
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* and resume with 16384. This minimizes the odds of OID conflict, by not
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* reassigning OIDs that might have been assigned during initdb.
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* ----------
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*/
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#define FirstBootstrapObjectId 10000
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#define FirstNormalObjectId 16384
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/*
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* VariableCache is a data structure in shared memory that is used to track
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* OID and XID assignment state. For largely historical reasons, there is
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* just one struct with different fields that are protected by different
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* LWLocks.
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*
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* Note: xidWrapLimit and oldestXidDB are not "active" values, but are
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* used just to generate useful messages when xidWarnLimit or xidStopLimit
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* are exceeded.
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*/
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typedef struct VariableCacheData
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{
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/*
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* These fields are protected by OidGenLock.
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*/
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Oid nextOid; /* next OID to assign */
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uint32 oidCount; /* OIDs available before must do XLOG work */
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/*
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* These fields are protected by XidGenLock.
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*/
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TransactionId nextXid; /* next XID to assign */
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TransactionId oldestXid; /* cluster-wide minimum datfrozenxid */
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TransactionId xidVacLimit; /* start forcing autovacuums here */
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TransactionId xidWarnLimit; /* start complaining here */
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TransactionId xidStopLimit; /* refuse to advance nextXid beyond here */
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TransactionId xidWrapLimit; /* where the world ends */
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Oid oldestXidDB; /* database with minimum datfrozenxid */
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/*
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* These fields are protected by CommitTsLock
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*/
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TransactionId oldestCommitTs;
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TransactionId newestCommitTs;
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/*
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* These fields are protected by ProcArrayLock.
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*/
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TransactionId latestCompletedXid; /* newest XID that has committed or
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* aborted */
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} VariableCacheData;
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typedef VariableCacheData *VariableCache;
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/* ----------------
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* extern declarations
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* ----------------
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*/
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/* in transam/xact.c */
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extern bool TransactionStartedDuringRecovery(void);
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/* in transam/varsup.c */
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extern PGDLLIMPORT VariableCache ShmemVariableCache;
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/*
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* prototypes for functions in transam/transam.c
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*/
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extern bool TransactionIdDidCommit(TransactionId transactionId);
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extern bool TransactionIdDidAbort(TransactionId transactionId);
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extern bool TransactionIdIsKnownCompleted(TransactionId transactionId);
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extern void TransactionIdAbort(TransactionId transactionId);
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extern void TransactionIdCommitTree(TransactionId xid, int nxids, TransactionId *xids);
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extern void TransactionIdAsyncCommitTree(TransactionId xid, int nxids, TransactionId *xids, XLogRecPtr lsn);
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extern void TransactionIdAbortTree(TransactionId xid, int nxids, TransactionId *xids);
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extern bool TransactionIdPrecedes(TransactionId id1, TransactionId id2);
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extern bool TransactionIdPrecedesOrEquals(TransactionId id1, TransactionId id2);
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extern bool TransactionIdFollows(TransactionId id1, TransactionId id2);
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extern bool TransactionIdFollowsOrEquals(TransactionId id1, TransactionId id2);
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extern TransactionId TransactionIdLatest(TransactionId mainxid,
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int nxids, const TransactionId *xids);
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extern XLogRecPtr TransactionIdGetCommitLSN(TransactionId xid);
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/* in transam/varsup.c */
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extern TransactionId GetNewTransactionId(bool isSubXact);
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extern TransactionId ReadNewTransactionId(void);
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extern void SetTransactionIdLimit(TransactionId oldest_datfrozenxid,
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Oid oldest_datoid);
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extern bool ForceTransactionIdLimitUpdate(void);
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extern Oid GetNewObjectId(void);
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#endif /* TRAMSAM_H */
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