src/include/storage/pmsignal.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * pmsignal.h
   4  *        routines for signaling between the postmaster and its child processes
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * src/include/storage/pmsignal.h
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #ifndef PMSIGNAL_H
  15 #define PMSIGNAL_H
  16
  17 #include <signal.h>
  18
  19 #ifdef HAVE_SYS_PRCTL_H
  20 #include "sys/prctl.h"
  21 #endif
  22
  23 #ifdef HAVE_SYS_PROCCTL_H
  24 #include "sys/procctl.h"
  25 #endif
  26
  27 /*
  28  * Reasons for signaling the postmaster.  We can cope with simultaneous
  29  * signals for different reasons.  If the same reason is signaled multiple
  30  * times in quick succession, however, the postmaster is likely to observe
  31  * only one notification of it.  This is okay for the present uses.
  32  */
  33 typedef enum
  34 {
  35         PMSIGNAL_RECOVERY_STARTED,      /* recovery has started */
  36         PMSIGNAL_BEGIN_HOT_STANDBY, /* begin Hot Standby */
  37         PMSIGNAL_ROTATE_LOGFILE,        /* send SIGUSR1 to syslogger to rotate logfile */
  38         PMSIGNAL_START_AUTOVAC_LAUNCHER,        /* start an autovacuum launcher */
  39         PMSIGNAL_START_AUTOVAC_WORKER,  /* start an autovacuum worker */
  40         PMSIGNAL_BACKGROUND_WORKER_CHANGE,      /* background worker state change */
  41         PMSIGNAL_START_WALRECEIVER, /* start a walreceiver */
  42         PMSIGNAL_ADVANCE_STATE_MACHINE, /* advance postmaster's state machine */
  43 } PMSignalReason;
  44
  45 #define NUM_PMSIGNALS (PMSIGNAL_ADVANCE_STATE_MACHINE+1)
  46
  47 /*
  48  * Reasons why the postmaster would send SIGQUIT to its children.
  49  */
  50 typedef enum
  51 {
  52         PMQUIT_NOT_SENT = 0,            /* postmaster hasn't sent SIGQUIT */
  53         PMQUIT_FOR_CRASH,                       /* some other backend bought the farm */
  54         PMQUIT_FOR_STOP,                        /* immediate stop was commanded */
  55 } QuitSignalReason;
  56
  57 /* PMSignalData is an opaque struct, details known only within pmsignal.c */
  58 typedef struct PMSignalData PMSignalData;
  59
  60 #ifdef EXEC_BACKEND
  61 extern PGDLLIMPORT volatile PMSignalData *PMSignalState;
  62 #endif
  63
  64 /*
  65  * prototypes for functions in pmsignal.c
  66  */
  67 extern Size PMSignalShmemSize(void);
  68 extern void PMSignalShmemInit(void);
  69 extern void SendPostmasterSignal(PMSignalReason reason);
  70 extern bool CheckPostmasterSignal(PMSignalReason reason);
  71 extern void SetQuitSignalReason(QuitSignalReason reason);
  72 extern QuitSignalReason GetQuitSignalReason(void);
  73 extern void MarkPostmasterChildSlotAssigned(int slot);
  74 extern bool MarkPostmasterChildSlotUnassigned(int slot);
  75 extern bool IsPostmasterChildWalSender(int slot);
  76 extern void RegisterPostmasterChildActive(void);
  77 extern void MarkPostmasterChildWalSender(void);
  78 extern bool PostmasterIsAliveInternal(void);
  79 extern void PostmasterDeathSignalInit(void);
  80
  81
  82 /*
  83  * Do we have a way to ask for a signal on parent death?
  84  *
  85  * If we do, pmsignal.c will set up a signal handler, that sets a flag when
  86  * the parent dies.  Checking the flag first makes PostmasterIsAlive() a lot
  87  * cheaper in usual case that the postmaster is alive.
  88  */
  89 #if (defined(HAVE_SYS_PRCTL_H) && defined(PR_SET_PDEATHSIG)) || \
  90         (defined(HAVE_SYS_PROCCTL_H) && defined(PROC_PDEATHSIG_CTL))
  91 #define USE_POSTMASTER_DEATH_SIGNAL
  92 #endif
  93
  94 #ifdef USE_POSTMASTER_DEATH_SIGNAL
  95 extern PGDLLIMPORT volatile sig_atomic_t postmaster_possibly_dead;
  96
  97 static inline bool
  98 PostmasterIsAlive(void)
  99 {
 100         if (likely(!postmaster_possibly_dead))
 101                 return true;
 102         return PostmasterIsAliveInternal();
 103 }
 104 #else
 105 #define PostmasterIsAlive() PostmasterIsAliveInternal()
 106 #endif
 107
 108 #endif                                                  /* PMSIGNAL_H */