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368d8270c8
Instead of talking about setting latches, which is a pretty low-level mechanism, emphasize that they wake up other processes. This is in preparation for replacing Latches with a new abstraction. That's still work in progress, but this seems a little tidier anyway, so let's get this refactoring out of the way already. Discussion: https://www.postgresql.org/message-id/391abe21-413e-4d91-a650-b663af49500c%40iki.fi
90 lines
2.4 KiB
C
90 lines
2.4 KiB
C
/*-------------------------------------------------------------------------
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*
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* xlogwait.h
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* Declarations for LSN replay waiting routines.
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*
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* Copyright (c) 2024, PostgreSQL Global Development Group
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*
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* src/include/access/xlogwait.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef XLOG_WAIT_H
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#define XLOG_WAIT_H
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#include "lib/pairingheap.h"
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#include "postgres.h"
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#include "port/atomics.h"
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#include "storage/procnumber.h"
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#include "storage/spin.h"
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#include "tcop/dest.h"
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/*
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* WaitLSNProcInfo - the shared memory structure representing information
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* about the single process, which may wait for LSN replay. An item of
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* waitLSN->procInfos array.
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*/
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typedef struct WaitLSNProcInfo
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{
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/* LSN, which this process is waiting for */
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XLogRecPtr waitLSN;
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/* Process to wake up once the waitLSN is replayed */
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ProcNumber procno;
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/* A pairing heap node for participation in waitLSNState->waitersHeap */
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pairingheap_node phNode;
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/*
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* A flag indicating that this item is present in
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* waitLSNState->waitersHeap
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*/
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bool inHeap;
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} WaitLSNProcInfo;
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/*
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* WaitLSNState - the shared memory state for the replay LSN waiting facility.
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*/
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typedef struct WaitLSNState
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{
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/*
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* The minimum LSN value some process is waiting for. Used for the
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* fast-path checking if we need to wake up any waiters after replaying a
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* WAL record. Could be read lock-less. Update protected by WaitLSNLock.
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*/
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pg_atomic_uint64 minWaitedLSN;
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/*
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* A pairing heap of waiting processes order by LSN values (least LSN is
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* on top). Protected by WaitLSNLock.
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*/
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pairingheap waitersHeap;
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/*
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* An array with per-process information, indexed by the process number.
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* Protected by WaitLSNLock.
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*/
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WaitLSNProcInfo procInfos[FLEXIBLE_ARRAY_MEMBER];
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} WaitLSNState;
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/*
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* Result statuses for WaitForLSNReplay().
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*/
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typedef enum
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{
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WAIT_LSN_RESULT_SUCCESS, /* Target LSN is reached */
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WAIT_LSN_RESULT_TIMEOUT, /* Timeout occurred */
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WAIT_LSN_RESULT_NOT_IN_RECOVERY, /* Recovery ended before or during our
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* wait */
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} WaitLSNResult;
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extern PGDLLIMPORT WaitLSNState *waitLSNState;
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extern Size WaitLSNShmemSize(void);
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extern void WaitLSNShmemInit(void);
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extern void WaitLSNWakeup(XLogRecPtr currentLSN);
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extern void WaitLSNCleanup(void);
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extern WaitLSNResult WaitForLSNReplay(XLogRecPtr targetLSN, int64 timeout);
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#endif /* XLOG_WAIT_H */
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