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pmsignal.h
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1 /*-------------------------------------------------------------------------
2  *
3  * pmsignal.h
4  * routines for signaling the postmaster from its child processes
5  *
6  *
7  * Portions Copyright (c) 1996-2019, 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_WAKEN_ARCHIVER, /* send a NOTIFY signal to xlog archiver */
38  PMSIGNAL_ROTATE_LOGFILE, /* send SIGUSR1 to syslogger to rotate logfile */
39  PMSIGNAL_START_AUTOVAC_LAUNCHER, /* start an autovacuum launcher */
40  PMSIGNAL_START_AUTOVAC_WORKER, /* start an autovacuum worker */
41  PMSIGNAL_BACKGROUND_WORKER_CHANGE, /* background worker state change */
42  PMSIGNAL_START_WALRECEIVER, /* start a walreceiver */
43  PMSIGNAL_ADVANCE_STATE_MACHINE, /* advance postmaster's state machine */
44 
45  NUM_PMSIGNALS /* Must be last value of enum! */
47 
48 /* PMSignalData is an opaque struct, details known only within pmsignal.c */
49 typedef struct PMSignalData PMSignalData;
50 
51 /*
52  * prototypes for functions in pmsignal.c
53  */
54 extern Size PMSignalShmemSize(void);
55 extern void PMSignalShmemInit(void);
56 extern void SendPostmasterSignal(PMSignalReason reason);
57 extern bool CheckPostmasterSignal(PMSignalReason reason);
58 extern int AssignPostmasterChildSlot(void);
59 extern bool ReleasePostmasterChildSlot(int slot);
60 extern bool IsPostmasterChildWalSender(int slot);
61 extern void MarkPostmasterChildActive(void);
62 extern void MarkPostmasterChildInactive(void);
63 extern void MarkPostmasterChildWalSender(void);
64 extern bool PostmasterIsAliveInternal(void);
65 extern void PostmasterDeathSignalInit(void);
66 
67 
68 /*
69  * Do we have a way to ask for a signal on parent death?
70  *
71  * If we do, pmsignal.c will set up a signal handler, that sets a flag when
72  * the parent dies. Checking the flag first makes PostmasterIsAlive() a lot
73  * cheaper in usual case that the postmaster is alive.
74  */
75 #if (defined(HAVE_SYS_PRCTL_H) && defined(PR_SET_PDEATHSIG)) || \
76  (defined(HAVE_SYS_PROCCTL_H) && defined(PROC_PDEATHSIG_CTL))
77 #define USE_POSTMASTER_DEATH_SIGNAL
78 #endif
79 
80 #ifdef USE_POSTMASTER_DEATH_SIGNAL
81 extern volatile sig_atomic_t postmaster_possibly_dead;
82 
83 static inline bool
85 {
86  if (likely(!postmaster_possibly_dead))
87  return true;
89 }
90 #else
91 #define PostmasterIsAlive() PostmasterIsAliveInternal()
92 #endif
93 
94 #endif /* PMSIGNAL_H */
void PMSignalShmemInit(void)
Definition: pmsignal.c:128
#define likely(x)
Definition: c.h:207
Size PMSignalShmemSize(void)
Definition: pmsignal.c:113
void PostmasterDeathSignalInit(void)
Definition: pmsignal.c:370
bool CheckPostmasterSignal(PMSignalReason reason)
Definition: pmsignal.c:163
void MarkPostmasterChildActive(void)
Definition: pmsignal.c:256
bool PostmasterIsAliveInternal(void)
Definition: pmsignal.c:309
#define PostmasterIsAlive()
Definition: pmsignal.h:91
bool IsPostmasterChildWalSender(int slot)
Definition: pmsignal.c:240
void MarkPostmasterChildInactive(void)
Definition: pmsignal.c:289
void SendPostmasterSignal(PMSignalReason reason)
Definition: pmsignal.c:146
int AssignPostmasterChildSlot(void)
Definition: pmsignal.c:184
size_t Size
Definition: c.h:466
void MarkPostmasterChildWalSender(void)
Definition: pmsignal.c:272
PMSignalReason
Definition: pmsignal.h:33
bool ReleasePostmasterChildSlot(int slot)
Definition: pmsignal.c:218