Line data    Source code

       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * pmsignal.h
       4             :  *    routines for signaling between the postmaster and its child processes
       5             :  *
       6             :  *
       7             :  * Portions Copyright (c) 1996-2025, 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             :     PMSIGNAL_XLOG_IS_SHUTDOWN,  /* ShutdownXLOG() completed */
      44             : } PMSignalReason;
      45             : 
      46             : #define NUM_PMSIGNALS (PMSIGNAL_XLOG_IS_SHUTDOWN+1)
      47             : 
      48             : /*
      49             :  * Reasons why the postmaster would send SIGQUIT to its children.
      50             :  */
      51             : typedef enum
      52             : {
      53             :     PMQUIT_NOT_SENT = 0,        /* postmaster hasn't sent SIGQUIT */
      54             :     PMQUIT_FOR_CRASH,           /* some other backend bought the farm */
      55             :     PMQUIT_FOR_STOP,            /* immediate stop was commanded */
      56             : } QuitSignalReason;
      57             : 
      58             : /* PMSignalData is an opaque struct, details known only within pmsignal.c */
      59             : typedef struct PMSignalData PMSignalData;
      60             : 
      61             : #ifdef EXEC_BACKEND
      62             : extern PGDLLIMPORT volatile PMSignalData *PMSignalState;
      63             : #endif
      64             : 
      65             : /*
      66             :  * prototypes for functions in pmsignal.c
      67             :  */
      68             : extern Size PMSignalShmemSize(void);
      69             : extern void PMSignalShmemInit(void);
      70             : extern void SendPostmasterSignal(PMSignalReason reason);
      71             : extern bool CheckPostmasterSignal(PMSignalReason reason);
      72             : extern void SetQuitSignalReason(QuitSignalReason reason);
      73             : extern QuitSignalReason GetQuitSignalReason(void);
      74             : extern void MarkPostmasterChildSlotAssigned(int slot);
      75             : extern bool MarkPostmasterChildSlotUnassigned(int slot);
      76             : extern bool IsPostmasterChildWalSender(int slot);
      77             : extern void RegisterPostmasterChildActive(void);
      78             : extern void MarkPostmasterChildWalSender(void);
      79             : extern bool PostmasterIsAliveInternal(void);
      80             : extern void PostmasterDeathSignalInit(void);
      81             : 
      82             : 
      83             : /*
      84             :  * Do we have a way to ask for a signal on parent death?
      85             :  *
      86             :  * If we do, pmsignal.c will set up a signal handler, that sets a flag when
      87             :  * the parent dies.  Checking the flag first makes PostmasterIsAlive() a lot
      88             :  * cheaper in usual case that the postmaster is alive.
      89             :  */
      90             : #if (defined(HAVE_SYS_PRCTL_H) && defined(PR_SET_PDEATHSIG)) || \
      91             :     (defined(HAVE_SYS_PROCCTL_H) && defined(PROC_PDEATHSIG_CTL))
      92             : #define USE_POSTMASTER_DEATH_SIGNAL
      93             : #endif
      94             : 
      95             : #ifdef USE_POSTMASTER_DEATH_SIGNAL
      96             : extern PGDLLIMPORT volatile sig_atomic_t postmaster_possibly_dead;
      97             : 
      98             : static inline bool
      99     5327260 : PostmasterIsAlive(void)
     100             : {
     101     5327260 :     if (likely(!postmaster_possibly_dead))
     102     5326664 :         return true;
     103         596 :     return PostmasterIsAliveInternal();
     104             : }
     105             : #else
     106             : #define PostmasterIsAlive() PostmasterIsAliveInternal()
     107             : #endif
     108             : 
     109             : #endif                          /* PMSIGNAL_H */