Age         Owner                  TLA  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) 1996-2023, 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                 : 
                                 44                 :     NUM_PMSIGNALS               /* Must be last value of enum! */
                                 45                 : } PMSignalReason;
                                 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                 : /*
                                 61                 :  * prototypes for functions in pmsignal.c
                                 62                 :  */
                                 63                 : extern Size PMSignalShmemSize(void);
                                 64                 : extern void PMSignalShmemInit(void);
                                 65                 : extern void SendPostmasterSignal(PMSignalReason reason);
                                 66                 : extern bool CheckPostmasterSignal(PMSignalReason reason);
                                 67                 : extern void SetQuitSignalReason(QuitSignalReason reason);
                                 68                 : extern QuitSignalReason GetQuitSignalReason(void);
                                 69                 : extern int  AssignPostmasterChildSlot(void);
                                 70                 : extern bool ReleasePostmasterChildSlot(int slot);
                                 71                 : extern bool IsPostmasterChildWalSender(int slot);
                                 72                 : extern void MarkPostmasterChildActive(void);
                                 73                 : extern void MarkPostmasterChildInactive(void);
                                 74                 : extern void MarkPostmasterChildWalSender(void);
                                 75                 : extern bool PostmasterIsAliveInternal(void);
                                 76                 : extern void PostmasterDeathSignalInit(void);
                                 77                 : 
                                 78                 : 
                                 79                 : /*
                                 80                 :  * Do we have a way to ask for a signal on parent death?
                                 81                 :  *
                                 82                 :  * If we do, pmsignal.c will set up a signal handler, that sets a flag when
                                 83                 :  * the parent dies.  Checking the flag first makes PostmasterIsAlive() a lot
                                 84                 :  * cheaper in usual case that the postmaster is alive.
                                 85                 :  */
                                 86                 : #if (defined(HAVE_SYS_PRCTL_H) && defined(PR_SET_PDEATHSIG)) || \
                                 87                 :     (defined(HAVE_SYS_PROCCTL_H) && defined(PROC_PDEATHSIG_CTL))
                                 88                 : #define USE_POSTMASTER_DEATH_SIGNAL
                                 89                 : #endif
                                 90                 : 
                                 91                 : #ifdef USE_POSTMASTER_DEATH_SIGNAL
                                 92                 : extern PGDLLIMPORT volatile sig_atomic_t postmaster_possibly_dead;
                                 93                 : 
                                 94                 : static inline bool
 1733 tmunro                     95 CBC     2492216 : PostmasterIsAlive(void)
                                 96                 : {
                                 97         2492216 :     if (likely(!postmaster_possibly_dead))
                                 98         2492058 :         return true;
                                 99             158 :     return PostmasterIsAliveInternal();
                                100                 : }
                                101                 : #else
                                102                 : #define PostmasterIsAlive() PostmasterIsAliveInternal()
                                103                 : #endif
                                104                 : 
                                105                 : #endif                          /* PMSIGNAL_H */