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/*-------------------------------------------------------------------------
*
* pmsignal.h
* routines for signaling between the postmaster and its child processes
*
*
* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/storage/pmsignal.h
*
*-------------------------------------------------------------------------
*/
#ifndef PMSIGNAL_H
#define PMSIGNAL_H
#include <signal.h>
#ifdef HAVE_SYS_PRCTL_H
#include "sys/prctl.h"
#endif
#ifdef HAVE_SYS_PROCCTL_H
#include "sys/procctl.h"
#endif
/*
* Reasons for signaling the postmaster. We can cope with simultaneous
* signals for different reasons. If the same reason is signaled multiple
* times in quick succession, however, the postmaster is likely to observe
* only one notification of it. This is okay for the present uses.
*/
typedef enum
{
PMSIGNAL_RECOVERY_STARTED, /* recovery has started */
PMSIGNAL_BEGIN_HOT_STANDBY, /* begin Hot Standby */
PMSIGNAL_ROTATE_LOGFILE, /* send SIGUSR1 to syslogger to rotate logfile */
PMSIGNAL_START_AUTOVAC_LAUNCHER, /* start an autovacuum launcher */
PMSIGNAL_START_AUTOVAC_WORKER, /* start an autovacuum worker */
PMSIGNAL_BACKGROUND_WORKER_CHANGE, /* background worker state change */
PMSIGNAL_START_WALRECEIVER, /* start a walreceiver */
PMSIGNAL_ADVANCE_STATE_MACHINE, /* advance postmaster's state machine */
NUM_PMSIGNALS /* Must be last value of enum! */
} PMSignalReason;
/*
* Reasons why the postmaster would send SIGQUIT to its children.
*/
typedef enum
{
PMQUIT_NOT_SENT = 0, /* postmaster hasn't sent SIGQUIT */
PMQUIT_FOR_CRASH, /* some other backend bought the farm */
PMQUIT_FOR_STOP /* immediate stop was commanded */
} QuitSignalReason;
/* PMSignalData is an opaque struct, details known only within pmsignal.c */
typedef struct PMSignalData PMSignalData;
/*
* prototypes for functions in pmsignal.c
*/
extern Size PMSignalShmemSize(void);
extern void PMSignalShmemInit(void);
extern void SendPostmasterSignal(PMSignalReason reason);
extern bool CheckPostmasterSignal(PMSignalReason reason);
extern void SetQuitSignalReason(QuitSignalReason reason);
extern QuitSignalReason GetQuitSignalReason(void);
extern int AssignPostmasterChildSlot(void);
extern bool ReleasePostmasterChildSlot(int slot);
extern bool IsPostmasterChildWalSender(int slot);
extern void MarkPostmasterChildActive(void);
extern void MarkPostmasterChildInactive(void);
extern void MarkPostmasterChildWalSender(void);
extern bool PostmasterIsAliveInternal(void);
extern void PostmasterDeathSignalInit(void);
/*
* Do we have a way to ask for a signal on parent death?
*
* If we do, pmsignal.c will set up a signal handler, that sets a flag when
* the parent dies. Checking the flag first makes PostmasterIsAlive() a lot
* cheaper in usual case that the postmaster is alive.
*/
#if (defined(HAVE_SYS_PRCTL_H) && defined(PR_SET_PDEATHSIG)) || \
(defined(HAVE_SYS_PROCCTL_H) && defined(PROC_PDEATHSIG_CTL))
#define USE_POSTMASTER_DEATH_SIGNAL
#endif
#ifdef USE_POSTMASTER_DEATH_SIGNAL
extern volatile sig_atomic_t postmaster_possibly_dead;
static inline bool
PostmasterIsAlive(void)
{
if (likely(!postmaster_possibly_dead))
return true;
return PostmasterIsAliveInternal();
}
#else
#define PostmasterIsAlive() PostmasterIsAliveInternal()
#endif
#endif /* PMSIGNAL_H */
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