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/*-------------------------------------------------------------------------
*
* snapmgr.h
* POSTGRES snapshot manager
*
* Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/utils/snapmgr.h
*
*-------------------------------------------------------------------------
*/
#ifndef SNAPMGR_H
#define SNAPMGR_H
#include "access/transam.h"
#include "utils/relcache.h"
#include "utils/resowner.h"
#include "utils/snapshot.h"
extern PGDLLIMPORT bool FirstSnapshotSet;
extern PGDLLIMPORT TransactionId TransactionXmin;
extern PGDLLIMPORT TransactionId RecentXmin;
/* Variables representing various special snapshot semantics */
extern PGDLLIMPORT SnapshotData SnapshotSelfData;
extern PGDLLIMPORT SnapshotData SnapshotAnyData;
extern PGDLLIMPORT SnapshotData SnapshotToastData;
#define SnapshotSelf (&SnapshotSelfData)
#define SnapshotAny (&SnapshotAnyData)
/* Use get_toast_snapshot() for the TOAST snapshot */
/*
* We don't provide a static SnapshotDirty variable because it would be
* non-reentrant. Instead, users of that snapshot type should declare a
* local variable of type SnapshotData, and initialize it with this macro.
*/
#define InitDirtySnapshot(snapshotdata) \
((snapshotdata).snapshot_type = SNAPSHOT_DIRTY)
/*
* Similarly, some initialization is required for a NonVacuumable snapshot.
* The caller must supply the visibility cutoff state to use (c.f.
* GlobalVisTestFor()).
*/
#define InitNonVacuumableSnapshot(snapshotdata, vistestp) \
((snapshotdata).snapshot_type = SNAPSHOT_NON_VACUUMABLE, \
(snapshotdata).vistest = (vistestp))
/* This macro encodes the knowledge of which snapshots are MVCC-safe */
#define IsMVCCSnapshot(snapshot) \
((snapshot)->snapshot_type == SNAPSHOT_MVCC || \
(snapshot)->snapshot_type == SNAPSHOT_HISTORIC_MVCC)
extern Snapshot GetTransactionSnapshot(void);
extern Snapshot GetLatestSnapshot(void);
extern void SnapshotSetCommandId(CommandId curcid);
extern Snapshot GetCatalogSnapshot(Oid relid);
extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid);
extern void InvalidateCatalogSnapshot(void);
extern void InvalidateCatalogSnapshotConditionally(void);
extern void PushActiveSnapshot(Snapshot snapshot);
extern void PushActiveSnapshotWithLevel(Snapshot snapshot, int snap_level);
extern void PushCopiedSnapshot(Snapshot snapshot);
extern void UpdateActiveSnapshotCommandId(void);
extern void PopActiveSnapshot(void);
extern Snapshot GetActiveSnapshot(void);
extern bool ActiveSnapshotSet(void);
extern Snapshot RegisterSnapshot(Snapshot snapshot);
extern void UnregisterSnapshot(Snapshot snapshot);
extern Snapshot RegisterSnapshotOnOwner(Snapshot snapshot, ResourceOwner owner);
extern void UnregisterSnapshotFromOwner(Snapshot snapshot, ResourceOwner owner);
extern void AtSubCommit_Snapshot(int level);
extern void AtSubAbort_Snapshot(int level);
extern void AtEOXact_Snapshot(bool isCommit, bool resetXmin);
extern void ImportSnapshot(const char *idstr);
extern bool XactHasExportedSnapshots(void);
extern void DeleteAllExportedSnapshotFiles(void);
extern void WaitForOlderSnapshots(TransactionId limitXmin, bool progress);
extern bool ThereAreNoPriorRegisteredSnapshots(void);
extern bool HaveRegisteredOrActiveSnapshot(void);
extern char *ExportSnapshot(Snapshot snapshot);
/*
* These live in procarray.c because they're intimately linked to the
* procarray contents, but thematically they better fit into snapmgr.h.
*/
typedef struct GlobalVisState GlobalVisState;
extern GlobalVisState *GlobalVisTestFor(Relation rel);
extern bool GlobalVisTestIsRemovableXid(GlobalVisState *state, TransactionId xid);
extern bool GlobalVisTestIsRemovableFullXid(GlobalVisState *state, FullTransactionId fxid);
extern bool GlobalVisCheckRemovableXid(Relation rel, TransactionId xid);
extern bool GlobalVisCheckRemovableFullXid(Relation rel, FullTransactionId fxid);
/*
* Utility functions for implementing visibility routines in table AMs.
*/
extern bool XidInMVCCSnapshot(TransactionId xid, Snapshot snapshot);
/* Support for catalog timetravel for logical decoding */
struct HTAB;
extern struct HTAB *HistoricSnapshotGetTupleCids(void);
extern void SetupHistoricSnapshot(Snapshot historic_snapshot, struct HTAB *tuplecids);
extern void TeardownHistoricSnapshot(bool is_error);
extern bool HistoricSnapshotActive(void);
extern Size EstimateSnapshotSpace(Snapshot snapshot);
extern void SerializeSnapshot(Snapshot snapshot, char *start_address);
extern Snapshot RestoreSnapshot(char *start_address);
extern void RestoreTransactionSnapshot(Snapshot snapshot, void *source_pgproc);
#endif /* SNAPMGR_H */
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