postgresql/src/include/storage/procsignal.h
Andres Freund 26669757b6 Handle logical slot conflicts on standby
During WAL replay on the standby, when a conflict with a logical slot is
identified, invalidate such slots. There are two sources of conflicts:
1) Using the information added in 6af1793954, logical slots are invalidated if
   required rows are removed
2) wal_level on the primary server is reduced to below logical

Uses the infrastructure introduced in the prior commit. FIXME: add commit
reference.

Change InvalidatePossiblyObsoleteSlot() to use a recovery conflict to
interrupt use of a slot, if called in the startup process. The new recovery
conflict is added to pg_stat_database_conflicts, as confl_active_logicalslot.

See 6af1793954 for an overall design of logical decoding on a standby.

Bumps catversion for the addition of the pg_stat_database_conflicts column.
Bumps PGSTAT_FILE_FORMAT_ID for the same reason.

Author: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com>
Author: Andres Freund <andres@anarazel.de>
Author: Amit Khandekar <amitdkhan.pg@gmail.com> (in an older version)
Reviewed-by: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Fabrízio de Royes Mello <fabriziomello@gmail.com>
Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://postgr.es/m/20230407075009.igg7be27ha2htkbt@awork3.anarazel.de
2023-04-08 00:05:44 -07:00

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C

/*-------------------------------------------------------------------------
*
* procsignal.h
* Routines for interprocess signaling
*
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/storage/procsignal.h
*
*-------------------------------------------------------------------------
*/
#ifndef PROCSIGNAL_H
#define PROCSIGNAL_H
#include "storage/backendid.h"
/*
* Reasons for signaling a Postgres child process (a backend or an auxiliary
* process, like checkpointer). We can cope with concurrent signals for different
* reasons. However, if the same reason is signaled multiple times in quick
* succession, the process is likely to observe only one notification of it.
* This is okay for the present uses.
*
* Also, because of race conditions, it's important that all the signals be
* defined so that no harm is done if a process mistakenly receives one.
*/
typedef enum
{
PROCSIG_CATCHUP_INTERRUPT, /* sinval catchup interrupt */
PROCSIG_NOTIFY_INTERRUPT, /* listen/notify interrupt */
PROCSIG_PARALLEL_MESSAGE, /* message from cooperating parallel backend */
PROCSIG_WALSND_INIT_STOPPING, /* ask walsenders to prepare for shutdown */
PROCSIG_BARRIER, /* global barrier interrupt */
PROCSIG_LOG_MEMORY_CONTEXT, /* ask backend to log the memory contexts */
PROCSIG_PARALLEL_APPLY_MESSAGE, /* Message from parallel apply workers */
/* Recovery conflict reasons */
PROCSIG_RECOVERY_CONFLICT_DATABASE,
PROCSIG_RECOVERY_CONFLICT_TABLESPACE,
PROCSIG_RECOVERY_CONFLICT_LOCK,
PROCSIG_RECOVERY_CONFLICT_SNAPSHOT,
PROCSIG_RECOVERY_CONFLICT_LOGICALSLOT,
PROCSIG_RECOVERY_CONFLICT_BUFFERPIN,
PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK,
NUM_PROCSIGNALS /* Must be last! */
} ProcSignalReason;
typedef enum
{
PROCSIGNAL_BARRIER_SMGRRELEASE /* ask smgr to close files */
} ProcSignalBarrierType;
/*
* prototypes for functions in procsignal.c
*/
extern Size ProcSignalShmemSize(void);
extern void ProcSignalShmemInit(void);
extern void ProcSignalInit(int pss_idx);
extern int SendProcSignal(pid_t pid, ProcSignalReason reason,
BackendId backendId);
extern uint64 EmitProcSignalBarrier(ProcSignalBarrierType type);
extern void WaitForProcSignalBarrier(uint64 generation);
extern void ProcessProcSignalBarrier(void);
extern void procsignal_sigusr1_handler(SIGNAL_ARGS);
#endif /* PROCSIGNAL_H */