PostgreSQL Source Code  git master
interrupt.c
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1 /*-------------------------------------------------------------------------
2  *
3  * interrupt.c
4  * Interrupt handling routines.
5  *
6  * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  * IDENTIFICATION
10  * src/backend/postmaster/interrupt.c
11  *
12  *-------------------------------------------------------------------------
13  */
14 
15 #include "postgres.h"
16 
17 #include <unistd.h>
18 
19 #include "miscadmin.h"
20 #include "postmaster/interrupt.h"
21 #include "storage/ipc.h"
22 #include "storage/latch.h"
23 #include "storage/procsignal.h"
24 #include "utils/guc.h"
25 #include "utils/memutils.h"
26 
27 volatile sig_atomic_t ConfigReloadPending = false;
28 volatile sig_atomic_t ShutdownRequestPending = false;
29 
30 /*
31  * Simple interrupt handler for main loops of background processes.
32  */
33 void
35 {
38 
40  {
41  ConfigReloadPending = false;
43  }
44 
46  proc_exit(0);
47 
48  /* Perform logging of memory contexts of this process */
51 }
52 
53 /*
54  * Simple signal handler for triggering a configuration reload.
55  *
56  * Normally, this handler would be used for SIGHUP. The idea is that code
57  * which uses it would arrange to check the ConfigReloadPending flag at
58  * convenient places inside main loops, or else call HandleMainLoopInterrupts.
59  */
60 void
62 {
63  int save_errno = errno;
64 
65  ConfigReloadPending = true;
67 
68  errno = save_errno;
69 }
70 
71 /*
72  * Simple signal handler for exiting quickly as if due to a crash.
73  *
74  * Normally, this would be used for handling SIGQUIT.
75  */
76 void
78 {
79  /*
80  * We DO NOT want to run proc_exit() or atexit() callbacks -- we're here
81  * because shared memory may be corrupted, so we don't want to try to
82  * clean up our transaction. Just nail the windows shut and get out of
83  * town. The callbacks wouldn't be safe to run from a signal handler,
84  * anyway.
85  *
86  * Note we do _exit(2) not _exit(0). This is to force the postmaster into
87  * a system reset cycle if someone sends a manual SIGQUIT to a random
88  * backend. This is necessary precisely because we don't clean up our
89  * shared memory state. (The "dead man switch" mechanism in pmsignal.c
90  * should ensure the postmaster sees this as a crash, too, but no harm in
91  * being doubly sure.)
92  */
93  _exit(2);
94 }
95 
96 /*
97  * Simple signal handler for triggering a long-running background process to
98  * shut down and exit.
99  *
100  * Typically, this handler would be used for SIGTERM, but some processes use
101  * other signals. In particular, the checkpointer exits on SIGUSR2, and the
102  * WAL writer exits on either SIGINT or SIGTERM.
103  *
104  * ShutdownRequestPending should be checked at a convenient place within the
105  * main loop, or else the main loop should call HandleMainLoopInterrupts.
106  */
107 void
109 {
110  int save_errno = errno;
111 
112  ShutdownRequestPending = true;
113  SetLatch(MyLatch);
114 
115  errno = save_errno;
116 }
#define SIGNAL_ARGS
Definition: c.h:1366
volatile sig_atomic_t LogMemoryContextPending
Definition: globals.c:38
volatile sig_atomic_t ProcSignalBarrierPending
Definition: globals.c:37
struct Latch * MyLatch
Definition: globals.c:58
@ PGC_SIGHUP
Definition: guc.h:72
void ProcessConfigFile(GucContext context)
void SignalHandlerForShutdownRequest(SIGNAL_ARGS)
Definition: interrupt.c:108
volatile sig_atomic_t ShutdownRequestPending
Definition: interrupt.c:28
volatile sig_atomic_t ConfigReloadPending
Definition: interrupt.c:27
void SignalHandlerForConfigReload(SIGNAL_ARGS)
Definition: interrupt.c:61
void SignalHandlerForCrashExit(SIGNAL_ARGS)
Definition: interrupt.c:77
void HandleMainLoopInterrupts(void)
Definition: interrupt.c:34
void proc_exit(int code)
Definition: ipc.c:104
void SetLatch(Latch *latch)
Definition: latch.c:591
void ProcessLogMemoryContextInterrupt(void)
Definition: mcxt.c:1041
void ProcessProcSignalBarrier(void)
Definition: procsignal.c:467