src/include/storage/procsignal.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * procsignal.h
   4  *        Routines for interprocess signaling
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * src/include/storage/procsignal.h
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #ifndef PROCSIGNAL_H
  15 #define PROCSIGNAL_H
  16
  17 #include "storage/backendid.h"
  18
  19
  20 /*
  21  * Reasons for signaling a Postgres child process (a backend or an auxiliary
  22  * process, like checkpointer).  We can cope with concurrent signals for different
  23  * reasons.  However, if the same reason is signaled multiple times in quick
  24  * succession, the process is likely to observe only one notification of it.
  25  * This is okay for the present uses.
  26  *
  27  * Also, because of race conditions, it's important that all the signals be
  28  * defined so that no harm is done if a process mistakenly receives one.
  29  */
  30 typedef enum
  31 {
  32         PROCSIG_CATCHUP_INTERRUPT,      /* sinval catchup interrupt */
  33         PROCSIG_NOTIFY_INTERRUPT,       /* listen/notify interrupt */
  34         PROCSIG_PARALLEL_MESSAGE,       /* message from cooperating parallel backend */
  35         PROCSIG_WALSND_INIT_STOPPING,   /* ask walsenders to prepare for shutdown  */
  36         PROCSIG_BARRIER,                        /* global barrier interrupt  */
  37         PROCSIG_LOG_MEMORY_CONTEXT, /* ask backend to log the memory contexts */
  38
  39         /* Recovery conflict reasons */
  40         PROCSIG_RECOVERY_CONFLICT_DATABASE,
  41         PROCSIG_RECOVERY_CONFLICT_TABLESPACE,
  42         PROCSIG_RECOVERY_CONFLICT_LOCK,
  43         PROCSIG_RECOVERY_CONFLICT_SNAPSHOT,
  44         PROCSIG_RECOVERY_CONFLICT_BUFFERPIN,
  45         PROCSIG_RECOVERY_CONFLICT_STARTUP_DEADLOCK,
  46
  47         NUM_PROCSIGNALS                         /* Must be last! */
  48 } ProcSignalReason;
  49
  50 typedef enum
  51 {
  52         /*
  53          * XXX. PROCSIGNAL_BARRIER_PLACEHOLDER should be replaced when the first
  54          * real user of the ProcSignalBarrier mechanism is added. It's just here
  55          * for now because we can't have an empty enum.
  56          */
  57         PROCSIGNAL_BARRIER_PLACEHOLDER = 0
  58 } ProcSignalBarrierType;
  59
  60 /*
  61  * prototypes for functions in procsignal.c
  62  */
  63 extern Size ProcSignalShmemSize(void);
  64 extern void ProcSignalShmemInit(void);
  65
  66 extern void ProcSignalInit(int pss_idx);
  67 extern int      SendProcSignal(pid_t pid, ProcSignalReason reason,
  68                                                    BackendId backendId);
  69
  70 extern uint64 EmitProcSignalBarrier(ProcSignalBarrierType type);
  71 extern void WaitForProcSignalBarrier(uint64 generation);
  72 extern void ProcessProcSignalBarrier(void);
  73
  74 extern void procsignal_sigusr1_handler(SIGNAL_ARGS);
  75
  76 #endif                                                  /* PROCSIGNAL_H */