1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
/*--------------------------------------------------------------------
* Symbols referenced in this file:
* - proc_exit_inprogress
* - proc_exit
*--------------------------------------------------------------------
*/
/*-------------------------------------------------------------------------
*
* ipc.c
* POSTGRES inter-process communication definitions.
*
* This file is misnamed, as it no longer has much of anything directly
* to do with IPC. The functionality here is concerned with managing
* exit-time cleanup for either a postmaster or a backend.
*
*
* Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/storage/ipc/ipc.c
*
*-------------------------------------------------------------------------
*/
/*
* This flag is set during proc_exit() to change ereport()'s behavior,
* so that an ereport() from an on_proc_exit routine cannot get us out
* of the exit procedure. We do NOT want to go back to the idle loop...
*/
__thread bool proc_exit_inprogress = false;
/*
* Set when shmem_exit() is in progress.
*/
/*
* This flag tracks whether we've called atexit() in the current process
* (or in the parent postmaster).
*/
/* local functions */
static void ;
/* ----------------------------------------------------------------
* exit() handling stuff
*
* These functions are in generally the same spirit as atexit(),
* but provide some additional features we need --- in particular,
* we want to register callbacks to invoke when we are disconnecting
* from a broken shared-memory context but not exiting the postmaster.
*
* Callback functions can take zero, one, or two args: the first passed
* arg is the integer exitcode, the second is the Datum supplied when
* the callback was registered.
* ----------------------------------------------------------------
*/
;
/* ----------------------------------------------------------------
* proc_exit
*
* this function calls all the callbacks registered
* for it (to free resources) and then calls exit.
*
* This should be the only function to call exit().
* -cim 2/6/90
*
* Unfortunately, we can't really guarantee that add-on code
* obeys the rule of not calling exit() directly. So, while
* this is the preferred way out of the system, we also register
* an atexit callback that will make sure cleanup happens.
* ----------------------------------------------------------------
*/
void
/*
* Code shared between proc_exit and the atexit handler. Note that in
* normal exit through proc_exit, this will actually be called twice ...
* but the second call will have nothing to do.
*/
/* ------------------
* Run all of the on_shmem_exit routines --- but don't actually exit.
* This is used by the postmaster to re-initialize shared memory and
* semaphores after a backend dies horribly. As with proc_exit(), we
* remove each callback from the list before calling it, to avoid
* infinite loop in case of error.
* ------------------
*/
/* ----------------------------------------------------------------
* atexit_callback
*
* Backstop to ensure that direct calls of exit() don't mess us up.
*
* Somebody who was being really uncooperative could call _exit(),
* but for that case we have a "dead man switch" that will make the
* postmaster treat it as a crash --- see pmsignal.c.
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* on_proc_exit
*
* this function adds a callback function to the list of
* functions invoked by proc_exit(). -cim 2/6/90
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* before_shmem_exit
*
* Register early callback to perform user-level cleanup,
* e.g. transaction abort, before we begin shutting down
* low-level subsystems.
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* on_shmem_exit
*
* Register ordinary callback to perform low-level shutdown
* (e.g. releasing our PGPROC); run after before_shmem_exit
* callbacks and before on_proc_exit callbacks.
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* cancel_before_shmem_exit
*
* this function removes a previously-registered before_shmem_exit
* callback. For simplicity, only the latest entry can be
* removed. (We could work harder but there is no need for
* current uses.)
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* on_exit_reset
*
* this function clears all on_proc_exit() and on_shmem_exit()
* registered functions. This is used just after forking a backend,
* so that the backend doesn't believe it should call the postmaster's
* on-exit routines when it exits...
* ----------------------------------------------------------------
*/