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Currently, WaitForLSNReplay() immediately throws an error if waiting for LSN replay is not successful. This commit teaches WaitForLSNReplay() to return the result of waiting, while making pg_wal_replay_wait() responsible for throwing an appropriate error. This is preparation to adding 'no_error' argument to pg_wal_replay_wait() and new function pg_wal_replay_wait_status(), which returns the last wait result status. Additionally, we stop distinguishing situations when we find our instance to be not in a recovery state before entering the waiting loop and inside the waiting loop. Standby promotion may happen at any moment, even between issuing a procedure call statement and pg_wal_replay_wait() doing a first check of recovery status. Thus, there is no pointing distinguishing these situations. Also, since we may exit the waiting loop and see our instance not in recovery without throwing an error, we need to deleteLSNWaiter() in that case. We do this unconditionally for the sake of simplicity, even if standby was already promoted after reaching the target LSN, the startup process surely already deleted us. Reported-by: Michael Paquier Discussion: https://postgr.es/m/ZtUF17gF0pNpwZDI%40paquier.xyz Reviewed-by: Michael Paquier, Pavel Borisov
93 lines
2.4 KiB
C
93 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/latch.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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/*
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* A pointer to the latch, which should be set once the waitLSN is
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* replayed.
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*/
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Latch *latch;
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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 WaitLSNSetLatches(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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