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/*-------------------------------------------------------------------------
*
* xact.h
* postgres transaction system definitions
*
*
* Portions Copyright (c) 1996-2023, 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/transam.h"
#include "access/xlogreader.h"
#include "datatype/timestamp.h"
#include "lib/stringinfo.h"
#include "nodes/pg_list.h"
#include "storage/relfilelocator.h"
#include "storage/sinval.h"
/*
* Maximum size of Global Transaction ID (including '\0').
*
* Note that the max value of GIDSIZE must fit in the uint16 gidlen,
* specified in TwoPhaseFileHeader.
*/
#define GIDSIZE 200
/*
* Xact isolation levels
*/
#define XACT_READ_UNCOMMITTED 0
#define XACT_READ_COMMITTED 1
#define XACT_REPEATABLE_READ 2
#define XACT_SERIALIZABLE 3
extern PGDLLIMPORT int DefaultXactIsoLevel;
extern PGDLLIMPORT 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 PGDLLIMPORT bool DefaultXactReadOnly;
extern PGDLLIMPORT bool XactReadOnly;
/* flag for logging statements in this transaction */
extern PGDLLIMPORT bool xact_is_sampled;
/*
* Xact is deferrable -- only meaningful (currently) for read only
* SERIALIZABLE transactions
*/
extern PGDLLIMPORT bool DefaultXactDeferrable;
extern PGDLLIMPORT 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 */
SYNCHRONOUS_COMMIT_REMOTE_APPLY /* wait for local and remote flush and
* remote apply */
} SyncCommitLevel;
/* Define the default setting for synchronous_commit */
#define SYNCHRONOUS_COMMIT_ON SYNCHRONOUS_COMMIT_REMOTE_FLUSH
/* Synchronous commit level */
extern PGDLLIMPORT int synchronous_commit;
/* used during logical streaming of a transaction */
extern PGDLLIMPORT TransactionId CheckXidAlive;
extern PGDLLIMPORT bool bsysscan;
/*
* Miscellaneous flag bits to record events which occur on the top level
* transaction. These flags are only persisted in MyXactFlags and are intended
* so we remember to do certain things later in the transaction. This is
* globally accessible, so can be set from anywhere in the code which requires
* recording flags.
*/
extern PGDLLIMPORT int MyXactFlags;
/*
* XACT_FLAGS_ACCESSEDTEMPNAMESPACE - set when a temporary object is accessed.
* We don't allow PREPARE TRANSACTION in that case.
*/
#define XACT_FLAGS_ACCESSEDTEMPNAMESPACE (1U << 0)
/*
* XACT_FLAGS_ACQUIREDACCESSEXCLUSIVELOCK - records whether the top level xact
* logged any Access Exclusive Locks.
*/
#define XACT_FLAGS_ACQUIREDACCESSEXCLUSIVELOCK (1U << 1)
/*
* XACT_FLAGS_NEEDIMMEDIATECOMMIT - records whether the top level statement
* is one that requires immediate commit, such as CREATE DATABASE.
*/
#define XACT_FLAGS_NEEDIMMEDIATECOMMIT (1U << 2)
/*
* XACT_FLAGS_PIPELINING - set when we complete an extended-query-protocol
* Execute message. This is useful for detecting that an implicit transaction
* block has been created via pipelining.
*/
#define XACT_FLAGS_PIPELINING (1U << 3)
/*
* start- and end-of-transaction callbacks for dynamically loaded modules
*/
typedef enum
{
XACT_EVENT_COMMIT,
XACT_EVENT_PARALLEL_COMMIT,
XACT_EVENT_ABORT,
XACT_EVENT_PARALLEL_ABORT,
XACT_EVENT_PREPARE,
XACT_EVENT_PRE_COMMIT,
XACT_EVENT_PARALLEL_PRE_COMMIT,
XACT_EVENT_PRE_PREPARE
} XactEvent;
typedef void (*XactCallback) (XactEvent event, void *arg);
typedef enum
{
SUBXACT_EVENT_START_SUB,
SUBXACT_EVENT_COMMIT_SUB,
SUBXACT_EVENT_ABORT_SUB,
SUBXACT_EVENT_PRE_COMMIT_SUB
} SubXactEvent;
typedef void (*SubXactCallback) (SubXactEvent event, SubTransactionId mySubid,
SubTransactionId parentSubid, void *arg);
/* Data structure for Save/RestoreTransactionCharacteristics */
typedef struct SavedTransactionCharacteristics
{
int save_XactIsoLevel;
bool save_XactReadOnly;
bool save_XactDeferrable;
} SavedTransactionCharacteristics;
/* ----------------
* transaction-related XLOG entries
* ----------------
*/
/*
* XLOG allows to store some information in high 4 bits of log record xl_info
* field. We use 3 for the opcode, and one about an optional flag variable.
*/
#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_INVALIDATIONS 0x60
/* free opcode 0x70 */
/* mask for filtering opcodes out of xl_info */
#define XLOG_XACT_OPMASK 0x70
/* does this record have a 'xinfo' field or not */
#define XLOG_XACT_HAS_INFO 0x80
/*
* The following flags, stored in xinfo, determine which information is
* contained in commit/abort records.
*/
#define XACT_XINFO_HAS_DBINFO (1U << 0)
#define XACT_XINFO_HAS_SUBXACTS (1U << 1)
#define XACT_XINFO_HAS_RELFILELOCATORS (1U << 2)
#define XACT_XINFO_HAS_INVALS (1U << 3)
#define XACT_XINFO_HAS_TWOPHASE (1U << 4)
#define XACT_XINFO_HAS_ORIGIN (1U << 5)
#define XACT_XINFO_HAS_AE_LOCKS (1U << 6)
#define XACT_XINFO_HAS_GID (1U << 7)
#define XACT_XINFO_HAS_DROPPED_STATS (1U << 8)
/*
* Also stored in xinfo, these 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_APPLY_FEEDBACK (1U << 29)
#define XACT_COMPLETION_UPDATE_RELCACHE_FILE (1U << 30)
#define XACT_COMPLETION_FORCE_SYNC_COMMIT (1U << 31)
/* Access macros for above flags */
#define XactCompletionApplyFeedback(xinfo) \
((xinfo & XACT_COMPLETION_APPLY_FEEDBACK) != 0)
#define XactCompletionRelcacheInitFileInval(xinfo) \
((xinfo & XACT_COMPLETION_UPDATE_RELCACHE_FILE) != 0)
#define XactCompletionForceSyncCommit(xinfo) \
((xinfo & XACT_COMPLETION_FORCE_SYNC_COMMIT) != 0)
typedef struct xl_xact_assignment
{
TransactionId xtop; /* assigned XID's top-level XID */
int nsubxacts; /* number of subtransaction XIDs */
TransactionId xsub[FLEXIBLE_ARRAY_MEMBER]; /* assigned subxids */
} xl_xact_assignment;
#define MinSizeOfXactAssignment offsetof(xl_xact_assignment, xsub)
/*
* Commit and abort records can contain a lot of information. But a large
* portion of the records won't need all possible pieces of information. So we
* only include what's needed.
*
* A minimal commit/abort record only consists of a xl_xact_commit/abort
* struct. The presence of additional information is indicated by bits set in
* 'xl_xact_xinfo->xinfo'. The presence of the xinfo field itself is signaled
* by a set XLOG_XACT_HAS_INFO bit in the xl_info field.
*
* NB: All the individual data chunks should be sized to multiples of
* sizeof(int) and only require int32 alignment. If they require bigger
* alignment, they need to be copied upon reading.
*/
/* sub-records for commit/abort */
typedef struct xl_xact_xinfo
{
/*
* Even though we right now only require two bytes of space in xinfo we
* use four so following records don't have to care about alignment.
* Commit records can be large, so copying large portions isn't
* attractive.
*/
uint32 xinfo;
} xl_xact_xinfo;
typedef struct xl_xact_dbinfo
{
Oid dbId; /* MyDatabaseId */
Oid tsId; /* MyDatabaseTableSpace */
} xl_xact_dbinfo;
typedef struct xl_xact_subxacts
{
int nsubxacts; /* number of subtransaction XIDs */
TransactionId subxacts[FLEXIBLE_ARRAY_MEMBER];
} xl_xact_subxacts;
#define MinSizeOfXactSubxacts offsetof(xl_xact_subxacts, subxacts)
typedef struct xl_xact_relfilelocators
{
int nrels; /* number of relations */
RelFileLocator xlocators[FLEXIBLE_ARRAY_MEMBER];
} xl_xact_relfilelocators;
#define MinSizeOfXactRelfileLocators offsetof(xl_xact_relfilelocators, xlocators)
/*
* A transactionally dropped statistics entry.
*
* Declared here rather than pgstat.h because pgstat.h can't be included from
* frontend code, but the WAL format needs to be readable by frontend
* programs.
*/
typedef struct xl_xact_stats_item
{
int kind;
Oid dboid;
Oid objoid;
} xl_xact_stats_item;
typedef struct xl_xact_stats_items
{
int nitems;
xl_xact_stats_item items[FLEXIBLE_ARRAY_MEMBER];
} xl_xact_stats_items;
#define MinSizeOfXactStatsItems offsetof(xl_xact_stats_items, items)
typedef struct xl_xact_invals
{
int nmsgs; /* number of shared inval msgs */
SharedInvalidationMessage msgs[FLEXIBLE_ARRAY_MEMBER];
} xl_xact_invals;
#define MinSizeOfXactInvals offsetof(xl_xact_invals, msgs)
typedef struct xl_xact_twophase
{
TransactionId xid;
} xl_xact_twophase;
typedef struct xl_xact_origin
{
XLogRecPtr origin_lsn;
TimestampTz origin_timestamp;
} xl_xact_origin;
typedef struct xl_xact_commit
{
TimestampTz xact_time; /* time of commit */
/* xl_xact_xinfo follows if XLOG_XACT_HAS_INFO */
/* xl_xact_dbinfo follows if XINFO_HAS_DBINFO */
/* xl_xact_subxacts follows if XINFO_HAS_SUBXACT */
/* xl_xact_relfilelocators follows if XINFO_HAS_RELFILELOCATORS */
/* xl_xact_stats_items follows if XINFO_HAS_DROPPED_STATS */
/* xl_xact_invals follows if XINFO_HAS_INVALS */
/* xl_xact_twophase follows if XINFO_HAS_TWOPHASE */
/* twophase_gid follows if XINFO_HAS_GID. As a null-terminated string. */
/* xl_xact_origin follows if XINFO_HAS_ORIGIN, stored unaligned! */
} xl_xact_commit;
#define MinSizeOfXactCommit (offsetof(xl_xact_commit, xact_time) + sizeof(TimestampTz))
typedef struct xl_xact_abort
{
TimestampTz xact_time; /* time of abort */
/* xl_xact_xinfo follows if XLOG_XACT_HAS_INFO */
/* xl_xact_dbinfo follows if XINFO_HAS_DBINFO */
/* xl_xact_subxacts follows if XINFO_HAS_SUBXACT */
/* xl_xact_relfilelocators follows if XINFO_HAS_RELFILELOCATORS */
/* xl_xact_stats_items follows if XINFO_HAS_DROPPED_STATS */
/* No invalidation messages needed. */
/* xl_xact_twophase follows if XINFO_HAS_TWOPHASE */
/* twophase_gid follows if XINFO_HAS_GID. As a null-terminated string. */
/* xl_xact_origin follows if XINFO_HAS_ORIGIN, stored unaligned! */
} xl_xact_abort;
#define MinSizeOfXactAbort sizeof(xl_xact_abort)
typedef struct xl_xact_prepare
{
uint32 magic; /* format identifier */
uint32 total_len; /* actual file length */
TransactionId xid; /* original transaction XID */
Oid database; /* OID of database it was in */
TimestampTz prepared_at; /* time of preparation */
Oid owner; /* user running the transaction */
int32 nsubxacts; /* number of following subxact XIDs */
int32 ncommitrels; /* number of delete-on-commit rels */
int32 nabortrels; /* number of delete-on-abort rels */
int32 ncommitstats; /* number of stats to drop on commit */
int32 nabortstats; /* number of stats to drop on abort */
int32 ninvalmsgs; /* number of cache invalidation messages */
bool initfileinval; /* does relcache init file need invalidation? */
uint16 gidlen; /* length of the GID - GID follows the header */
XLogRecPtr origin_lsn; /* lsn of this record at origin node */
TimestampTz origin_timestamp; /* time of prepare at origin node */
} xl_xact_prepare;
/*
* Commit/Abort records in the above form are a bit verbose to parse, so
* there's a deconstructed versions generated by ParseCommit/AbortRecord() for
* easier consumption.
*/
typedef struct xl_xact_parsed_commit
{
TimestampTz xact_time;
uint32 xinfo;
Oid dbId; /* MyDatabaseId */
Oid tsId; /* MyDatabaseTableSpace */
int nsubxacts;
TransactionId *subxacts;
int nrels;
RelFileLocator *xlocators;
int nstats;
xl_xact_stats_item *stats;
int nmsgs;
SharedInvalidationMessage *msgs;
TransactionId twophase_xid; /* only for 2PC */
char twophase_gid[GIDSIZE]; /* only for 2PC */
int nabortrels; /* only for 2PC */
RelFileLocator *abortlocators; /* only for 2PC */
int nabortstats; /* only for 2PC */
xl_xact_stats_item *abortstats; /* only for 2PC */
XLogRecPtr origin_lsn;
TimestampTz origin_timestamp;
} xl_xact_parsed_commit;
typedef xl_xact_parsed_commit xl_xact_parsed_prepare;
typedef struct xl_xact_parsed_abort
{
TimestampTz xact_time;
uint32 xinfo;
Oid dbId; /* MyDatabaseId */
Oid tsId; /* MyDatabaseTableSpace */
int nsubxacts;
TransactionId *subxacts;
int nrels;
RelFileLocator *xlocators;
int nstats;
xl_xact_stats_item *stats;
TransactionId twophase_xid; /* only for 2PC */
char twophase_gid[GIDSIZE]; /* only for 2PC */
XLogRecPtr origin_lsn;
TimestampTz origin_timestamp;
} xl_xact_parsed_abort;
/* ----------------
* 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 FullTransactionId GetTopFullTransactionId(void);
extern FullTransactionId GetTopFullTransactionIdIfAny(void);
extern FullTransactionId GetCurrentFullTransactionId(void);
extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
extern void MarkCurrentTransactionIdLoggedIfAny(void);
extern bool SubTransactionIsActive(SubTransactionId subxid);
extern CommandId GetCurrentCommandId(bool used);
extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
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 SaveTransactionCharacteristics(SavedTransactionCharacteristics *s);
extern void RestoreTransactionCharacteristics(const SavedTransactionCharacteristics *s);
extern void CommitTransactionCommand(void);
extern void AbortCurrentTransaction(void);
extern void BeginTransactionBlock(void);
extern bool EndTransactionBlock(bool chain);
extern bool PrepareTransactionBlock(const char *gid);
extern void UserAbortTransactionBlock(bool chain);
extern void BeginImplicitTransactionBlock(void);
extern void EndImplicitTransactionBlock(void);
extern void ReleaseSavepoint(const char *name);
extern void DefineSavepoint(const char *name);
extern void RollbackToSavepoint(const char *name);
extern void BeginInternalSubTransaction(const char *name);
extern void ReleaseCurrentSubTransaction(void);
extern void RollbackAndReleaseCurrentSubTransaction(void);
extern bool IsSubTransaction(void);
extern Size EstimateTransactionStateSpace(void);
extern void SerializeTransactionState(Size maxsize, char *start_address);
extern void StartParallelWorkerTransaction(char *tstatespace);
extern void EndParallelWorkerTransaction(void);
extern bool IsTransactionBlock(void);
extern bool IsTransactionOrTransactionBlock(void);
extern char TransactionBlockStatusCode(void);
extern void AbortOutOfAnyTransaction(void);
extern void PreventInTransactionBlock(bool isTopLevel, const char *stmtType);
extern void RequireTransactionBlock(bool isTopLevel, const char *stmtType);
extern void WarnNoTransactionBlock(bool isTopLevel, const char *stmtType);
extern bool IsInTransactionBlock(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 bool IsSubxactTopXidLogPending(void);
extern void MarkSubxactTopXidLogged(void);
extern int xactGetCommittedChildren(TransactionId **ptr);
extern XLogRecPtr XactLogCommitRecord(TimestampTz commit_time,
int nsubxacts, TransactionId *subxacts,
int nrels, RelFileLocator *rels,
int ndroppedstats,
xl_xact_stats_item *droppedstats,
int nmsgs, SharedInvalidationMessage *msgs,
bool relcacheInval,
int xactflags,
TransactionId twophase_xid,
const char *twophase_gid);
extern XLogRecPtr XactLogAbortRecord(TimestampTz abort_time,
int nsubxacts, TransactionId *subxacts,
int nrels, RelFileLocator *rels,
int ndroppedstats,
xl_xact_stats_item *droppedstats,
int xactflags, TransactionId twophase_xid,
const char *twophase_gid);
extern void xact_redo(XLogReaderState *record);
/* xactdesc.c */
extern void xact_desc(StringInfo buf, XLogReaderState *record);
extern const char *xact_identify(uint8 info);
/* also in xactdesc.c, so they can be shared between front/backend code */
extern void ParseCommitRecord(uint8 info, xl_xact_commit *xlrec, xl_xact_parsed_commit *parsed);
extern void ParseAbortRecord(uint8 info, xl_xact_abort *xlrec, xl_xact_parsed_abort *parsed);
extern void ParsePrepareRecord(uint8 info, xl_xact_prepare *xlrec, xl_xact_parsed_prepare *parsed);
extern void EnterParallelMode(void);
extern void ExitParallelMode(void);
extern bool IsInParallelMode(void);
#endif /* XACT_H */