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xact.h
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/*------------------------------------------------------------------------- * * xact.h * postgres transaction system definitions * * * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * src/include/access/xact.h * *------------------------------------------------------------------------- */ #ifndef XACT_H #define XACT_H #include "access/xlog.h" #include "nodes/pg_list.h" #include "storage/relfilenode.h" /* * Xact isolation levels */ #define XACT_READ_UNCOMMITTED 0 #define XACT_READ_COMMITTED 1 #define XACT_REPEATABLE_READ 2 #define XACT_SERIALIZABLE 3 extern int DefaultXactIsoLevel; extern int XactIsoLevel; /* * We implement three isolation levels internally. * The two stronger ones use one snapshot per database transaction; * the others use one snapshot per statement. * Serializable uses predicate locks in addition to snapshots. * These macros should be used to check which isolation level is selected. */ #define IsolationUsesXactSnapshot() (XactIsoLevel >= XACT_REPEATABLE_READ) #define IsolationIsSerializable() (XactIsoLevel == XACT_SERIALIZABLE) /* Xact read-only state */ extern bool DefaultXactReadOnly; extern bool XactReadOnly; /* * Xact is deferrable -- only meaningful (currently) for read only * SERIALIZABLE transactions */ extern bool DefaultXactDeferrable; extern bool XactDeferrable; typedef enum { SYNCHRONOUS_COMMIT_OFF, /* asynchronous commit */ SYNCHRONOUS_COMMIT_LOCAL_FLUSH, /* wait for local flush only */ SYNCHRONOUS_COMMIT_REMOTE_WRITE, /* wait for local flush and remote * write */ SYNCHRONOUS_COMMIT_REMOTE_FLUSH /* wait for local and remote flush */ } SyncCommitLevel; /* Define the default setting for synchronous_commit */ #define SYNCHRONOUS_COMMIT_ON SYNCHRONOUS_COMMIT_REMOTE_FLUSH /* Synchronous commit level */ extern int synchronous_commit; /* Kluge for 2PC support */ extern bool MyXactAccessedTempRel; /* * start- and end-of-transaction callbacks for dynamically loaded modules */ typedef enum { XACT_EVENT_COMMIT, XACT_EVENT_ABORT, XACT_EVENT_PREPARE } XactEvent; typedef void (*XactCallback) (XactEvent event, void *arg); typedef enum { SUBXACT_EVENT_START_SUB, SUBXACT_EVENT_COMMIT_SUB, SUBXACT_EVENT_ABORT_SUB } SubXactEvent; typedef void (*SubXactCallback) (SubXactEvent event, SubTransactionId mySubid, SubTransactionId parentSubid, void *arg); /* ---------------- * transaction-related XLOG entries * ---------------- */ /* * XLOG allows to store some information in high 4 bits of log * record xl_info field */ #define XLOG_XACT_COMMIT 0x00 #define XLOG_XACT_PREPARE 0x10 #define XLOG_XACT_ABORT 0x20 #define XLOG_XACT_COMMIT_PREPARED 0x30 #define XLOG_XACT_ABORT_PREPARED 0x40 #define XLOG_XACT_ASSIGNMENT 0x50 #define XLOG_XACT_COMMIT_COMPACT 0x60 typedef struct xl_xact_assignment { TransactionId xtop; /* assigned XID's top-level XID */ int nsubxacts; /* number of subtransaction XIDs */ TransactionId xsub[1]; /* assigned subxids */ } xl_xact_assignment; #define MinSizeOfXactAssignment offsetof(xl_xact_assignment, xsub) typedef struct xl_xact_commit_compact { TimestampTz xact_time; /* time of commit */ int nsubxacts; /* number of subtransaction XIDs */ /* ARRAY OF COMMITTED SUBTRANSACTION XIDs FOLLOWS */ TransactionId subxacts[1]; /* VARIABLE LENGTH ARRAY */ } xl_xact_commit_compact; #define MinSizeOfXactCommitCompact offsetof(xl_xact_commit_compact, subxacts) typedef struct xl_xact_commit { TimestampTz xact_time; /* time of commit */ uint32 xinfo; /* info flags */ int nrels; /* number of RelFileNodes */ int nsubxacts; /* number of subtransaction XIDs */ int nmsgs; /* number of shared inval msgs */ Oid dbId; /* MyDatabaseId */ Oid tsId; /* MyDatabaseTableSpace */ /* Array of RelFileNode(s) to drop at commit */ RelFileNode xnodes[1]; /* VARIABLE LENGTH ARRAY */ /* ARRAY OF COMMITTED SUBTRANSACTION XIDs FOLLOWS */ /* ARRAY OF SHARED INVALIDATION MESSAGES FOLLOWS */ } xl_xact_commit; #define MinSizeOfXactCommit offsetof(xl_xact_commit, xnodes) /* * These flags are set in the xinfo fields of WAL commit records, * indicating a variety of additional actions that need to occur * when emulating transaction effects during recovery. * They are named XactCompletion... to differentiate them from * EOXact... routines which run at the end of the original * transaction completion. */ #define XACT_COMPLETION_UPDATE_RELCACHE_FILE 0x01 #define XACT_COMPLETION_FORCE_SYNC_COMMIT 0x02 /* Access macros for above flags */ #define XactCompletionRelcacheInitFileInval(xinfo) (xinfo & XACT_COMPLETION_UPDATE_RELCACHE_FILE) #define XactCompletionForceSyncCommit(xinfo) (xinfo & XACT_COMPLETION_FORCE_SYNC_COMMIT) typedef struct xl_xact_abort { TimestampTz xact_time; /* time of abort */ int nrels; /* number of RelFileNodes */ int nsubxacts; /* number of subtransaction XIDs */ /* Array of RelFileNode(s) to drop at abort */ RelFileNode xnodes[1]; /* VARIABLE LENGTH ARRAY */ /* ARRAY OF ABORTED SUBTRANSACTION XIDs FOLLOWS */ } xl_xact_abort; /* Note the intentional lack of an invalidation message array c.f. commit */ #define MinSizeOfXactAbort offsetof(xl_xact_abort, xnodes) /* * COMMIT_PREPARED and ABORT_PREPARED are identical to COMMIT/ABORT records * except that we have to store the XID of the prepared transaction explicitly * --- the XID in the record header will be invalid. */ typedef struct xl_xact_commit_prepared { TransactionId xid; /* XID of prepared xact */ xl_xact_commit crec; /* COMMIT record */ /* MORE DATA FOLLOWS AT END OF STRUCT */ } xl_xact_commit_prepared; #define MinSizeOfXactCommitPrepared offsetof(xl_xact_commit_prepared, crec.xnodes) typedef struct xl_xact_abort_prepared { TransactionId xid; /* XID of prepared xact */ xl_xact_abort arec; /* ABORT record */ /* MORE DATA FOLLOWS AT END OF STRUCT */ } xl_xact_abort_prepared; #define MinSizeOfXactAbortPrepared offsetof(xl_xact_abort_prepared, arec.xnodes) /* ---------------- * extern definitions * ---------------- */ extern bool IsTransactionState(void); extern bool IsAbortedTransactionBlockState(void); extern TransactionId GetTopTransactionId(void); extern TransactionId GetTopTransactionIdIfAny(void); extern TransactionId GetCurrentTransactionId(void); extern TransactionId GetCurrentTransactionIdIfAny(void); extern TransactionId GetStableLatestTransactionId(void); extern SubTransactionId GetCurrentSubTransactionId(void); extern bool SubTransactionIsActive(SubTransactionId subxid); extern CommandId GetCurrentCommandId(bool used); extern TimestampTz GetCurrentTransactionStartTimestamp(void); extern TimestampTz GetCurrentStatementStartTimestamp(void); extern TimestampTz GetCurrentTransactionStopTimestamp(void); extern void SetCurrentStatementStartTimestamp(void); extern int GetCurrentTransactionNestLevel(void); extern bool TransactionIdIsCurrentTransactionId(TransactionId xid); extern void CommandCounterIncrement(void); extern void ForceSyncCommit(void); extern void StartTransactionCommand(void); extern void CommitTransactionCommand(void); extern void AbortCurrentTransaction(void); extern void BeginTransactionBlock(void); extern bool EndTransactionBlock(void); extern bool PrepareTransactionBlock(char *gid); extern void UserAbortTransactionBlock(void); extern void ReleaseSavepoint(List *options); extern void DefineSavepoint(char *name); extern void RollbackToSavepoint(List *options); extern void BeginInternalSubTransaction(char *name); extern void ReleaseCurrentSubTransaction(void); extern void RollbackAndReleaseCurrentSubTransaction(void); extern bool IsSubTransaction(void); extern bool IsTransactionBlock(void); extern bool IsTransactionOrTransactionBlock(void); extern char TransactionBlockStatusCode(void); extern void AbortOutOfAnyTransaction(void); extern void PreventTransactionChain(bool isTopLevel, const char *stmtType); extern void RequireTransactionChain(bool isTopLevel, const char *stmtType); extern bool IsInTransactionChain(bool isTopLevel); extern void RegisterXactCallback(XactCallback callback, void *arg); extern void UnregisterXactCallback(XactCallback callback, void *arg); extern void RegisterSubXactCallback(SubXactCallback callback, void *arg); extern void UnregisterSubXactCallback(SubXactCallback callback, void *arg); extern int xactGetCommittedChildren(TransactionId **ptr); extern void xact_redo(XLogRecPtr lsn, XLogRecord *record); extern void xact_desc(StringInfo buf, uint8 xl_info, char *rec); #endif /* XACT_H */