1/*-------------------------------------------------------------------------
2 *
3 * ipc.h
4 * POSTGRES inter-process communication definitions.
5 *
6 * This file is misnamed, as it no longer has much of anything directly
7 * to do with IPC. The functionality here is concerned with managing
8 * exit-time cleanup for either a postmaster or a backend.
9 *
10 *
11 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
12 * Portions Copyright (c) 1994, Regents of the University of California
13 *
14 * src/include/storage/ipc.h
15 *
16 *-------------------------------------------------------------------------
17 */
18#ifndef IPC_H
19#define IPC_H
20
21typedef void (*pg_on_exit_callback) (int code, Datum arg);
22typedef void (*shmem_startup_hook_type) (void);
23
24/*----------
25 * API for handling cleanup that must occur during either ereport(ERROR)
26 * or ereport(FATAL) exits from a block of code. (Typical examples are
27 * undoing transient changes to shared-memory state.)
28 *
29 * PG_ENSURE_ERROR_CLEANUP(cleanup_function, arg);
30 * {
31 * ... code that might throw ereport(ERROR) or ereport(FATAL) ...
32 * }
33 * PG_END_ENSURE_ERROR_CLEANUP(cleanup_function, arg);
34 *
35 * where the cleanup code is in a function declared per pg_on_exit_callback.
36 * The Datum value "arg" can carry any information the cleanup function
37 * needs.
38 *
39 * This construct ensures that cleanup_function() will be called during
40 * either ERROR or FATAL exits. It will not be called on successful
41 * exit from the controlled code. (If you want it to happen then too,
42 * call the function yourself from just after the construct.)
43 *
44 * Note: the macro arguments are multiply evaluated, so avoid side-effects.
45 *----------
46 */
47#define PG_ENSURE_ERROR_CLEANUP(cleanup_function, arg) \
48 do { \
49 before_shmem_exit(cleanup_function, arg); \
50 PG_TRY()
51
52#define PG_END_ENSURE_ERROR_CLEANUP(cleanup_function, arg) \
53 cancel_before_shmem_exit(cleanup_function, arg); \
54 PG_CATCH(); \
55 { \
56 cancel_before_shmem_exit(cleanup_function, arg); \
57 cleanup_function (0, arg); \
58 PG_RE_THROW(); \
59 } \
60 PG_END_TRY(); \
61 } while (0)
62
63
64/* ipc.c */
65extern PGDLLIMPORT bool proc_exit_inprogress;
66extern PGDLLIMPORT bool shmem_exit_inprogress;
67
68extern void proc_exit(int code) pg_attribute_noreturn();
69extern void shmem_exit(int code);
70extern void on_proc_exit(pg_on_exit_callback function, Datum arg);
71extern void on_shmem_exit(pg_on_exit_callback function, Datum arg);
72extern void before_shmem_exit(pg_on_exit_callback function, Datum arg);
73extern void cancel_before_shmem_exit(pg_on_exit_callback function, Datum arg);
74extern void on_exit_reset(void);
75
76/* ipci.c */
77extern PGDLLIMPORT shmem_startup_hook_type shmem_startup_hook;
78
79extern void CreateSharedMemoryAndSemaphores(int port);
80
81#endif /* IPC_H */
82