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
      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 */