1 /*-------------------------------------------------------------------------
2 *
3 * pmsignal.h
4 * routines for signaling between the postmaster and its child processes
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/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 volatile sig_atomic_t postmaster_possibly_dead;
93
94 static inline bool
PostmasterIsAlive(void)95 PostmasterIsAlive(void)
96 {
97 if (likely(!postmaster_possibly_dead))
98 return true;
99 return PostmasterIsAliveInternal();
100 }
101 #else
102 #define PostmasterIsAlive() PostmasterIsAliveInternal()
103 #endif
104
105 #endif /* PMSIGNAL_H */
106