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/*-------------------------------------------------------------------------
*
* procsignal.h
* Routines for interprocess signaling
*
*
* Portions Copyright (c) 1996-2025, 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/procnumber.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_GET_MEMORY_CONTEXT, /* ask backend to send the memory contexts */
PROCSIG_PARALLEL_APPLY_MESSAGE, /* Message from parallel apply workers */
/* Recovery conflict reasons */
PROCSIG_RECOVERY_CONFLICT_FIRST,
PROCSIG_RECOVERY_CONFLICT_DATABASE = PROCSIG_RECOVERY_CONFLICT_FIRST,
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,
PROCSIG_RECOVERY_CONFLICT_LAST = PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK,
} ProcSignalReason;
#define NUM_PROCSIGNALS (PROCSIG_RECOVERY_CONFLICT_LAST + 1)
typedef enum
{
PROCSIGNAL_BARRIER_SMGRRELEASE, /* ask smgr to close files */
} ProcSignalBarrierType;
/*
* Length of query cancel keys generated.
*
* Note that the protocol allows for longer keys, or shorter, but this is the
* length we actually generate. Client code, and the server code that handles
* incoming cancellation packets from clients, mustn't use this hardcoded
* length.
*/
#define MAX_CANCEL_KEY_LENGTH 32
/*
* prototypes for functions in procsignal.c
*/
extern Size ProcSignalShmemSize(void);
extern void ProcSignalShmemInit(void);
extern void ProcSignalInit(char *cancel_key, int cancel_key_len);
extern int SendProcSignal(pid_t pid, ProcSignalReason reason,
ProcNumber procNumber);
extern void SendCancelRequest(int backendPID, char *cancel_key, int cancel_key_len);
extern uint64 EmitProcSignalBarrier(ProcSignalBarrierType type);
extern void WaitForProcSignalBarrier(uint64 generation);
extern void ProcessProcSignalBarrier(void);
extern void procsignal_sigusr1_handler(SIGNAL_ARGS);
/* ProcSignalHeader is an opaque struct, details known only within procsignal.c */
typedef struct ProcSignalHeader ProcSignalHeader;
#ifdef EXEC_BACKEND
extern PGDLLIMPORT ProcSignalHeader *ProcSignal;
#endif
#endif /* PROCSIGNAL_H */
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