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4eb2176318
Previously, it was possible for DROP DATABASE, DROP TABLESPACE and ALTER
DATABASE SET TABLESPACE to fail because other backends still had file
handles open for dropped tables. Windows won't allow a directory
containing unlinked-but-still-open files to be unlinked. Tackle this
problem by forcing all backends to close all smgr fds. No change for
Unix systems, which don't suffer from the problem, but the new code path
can be tested by Unix-based developers by defining
USE_BARRIER_SMGRRELEASE explicitly.
It's possible that PROCSIGNAL_BARRIER_SMGRRELEASE will have more
bug-fixing applications soon (under discussion). Note that this is the
first user of the ProcSignalBarrier mechanism from commit 16a4e4aec. It
could in principle be back-patched as far as 14, but since field
complaints are rare and ProcSignalBarrier hasn't been battle-tested,
that seems like a bad idea. Fix in master only, where these failures
have started to show up in automated testing due to new tests.
Suggested-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Discussion: https://postgr.es/m/CA+hUKGLdemy2gBm80kz20GTe6hNVwoErE8KwcJk6-U56oStjtg@mail.gmail.com
72 lines
2.3 KiB
C
72 lines
2.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* procsignal.h
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* Routines for interprocess signaling
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*
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*
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* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/storage/procsignal.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PROCSIGNAL_H
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#define PROCSIGNAL_H
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#include "storage/backendid.h"
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/*
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* Reasons for signaling a Postgres child process (a backend or an auxiliary
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* process, like checkpointer). We can cope with concurrent signals for different
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* reasons. However, if the same reason is signaled multiple times in quick
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* succession, the process is likely to observe only one notification of it.
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* This is okay for the present uses.
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*
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* Also, because of race conditions, it's important that all the signals be
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* defined so that no harm is done if a process mistakenly receives one.
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*/
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typedef enum
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{
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PROCSIG_CATCHUP_INTERRUPT, /* sinval catchup interrupt */
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PROCSIG_NOTIFY_INTERRUPT, /* listen/notify interrupt */
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PROCSIG_PARALLEL_MESSAGE, /* message from cooperating parallel backend */
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PROCSIG_WALSND_INIT_STOPPING, /* ask walsenders to prepare for shutdown */
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PROCSIG_BARRIER, /* global barrier interrupt */
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PROCSIG_LOG_MEMORY_CONTEXT, /* ask backend to log the memory contexts */
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/* Recovery conflict reasons */
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PROCSIG_RECOVERY_CONFLICT_DATABASE,
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PROCSIG_RECOVERY_CONFLICT_TABLESPACE,
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PROCSIG_RECOVERY_CONFLICT_LOCK,
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PROCSIG_RECOVERY_CONFLICT_SNAPSHOT,
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PROCSIG_RECOVERY_CONFLICT_BUFFERPIN,
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PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK,
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NUM_PROCSIGNALS /* Must be last! */
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} ProcSignalReason;
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typedef enum
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{
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PROCSIGNAL_BARRIER_SMGRRELEASE /* ask smgr to close files */
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} ProcSignalBarrierType;
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/*
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* prototypes for functions in procsignal.c
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*/
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extern Size ProcSignalShmemSize(void);
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extern void ProcSignalShmemInit(void);
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extern void ProcSignalInit(int pss_idx);
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extern int SendProcSignal(pid_t pid, ProcSignalReason reason,
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BackendId backendId);
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extern uint64 EmitProcSignalBarrier(ProcSignalBarrierType type);
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extern void WaitForProcSignalBarrier(uint64 generation);
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extern void ProcessProcSignalBarrier(void);
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extern void procsignal_sigusr1_handler(SIGNAL_ARGS);
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#endif /* PROCSIGNAL_H */
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