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postgres/src/include/storage/ipc.h
Heikki Linnakangas 1fc2e9fbc0 Introduce a registry of built-in shmem subsystems
To add a new built-in subsystem, add it to subsystemslist.h. That
hooks up its shmem callbacks so that they get called at the right
times during postmaster startup. For now this is unused, but will
replace the current SubsystemShmemSize() and SubsystemShmemInit()
calls in the next commits.

Reviewed-by: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Matthias van de Meent <boekewurm+postgres@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://www.postgresql.org/message-id/CAExHW5vM1bneLYfg0wGeAa=52UiJ3z4vKd3AJ72X8Fw6k3KKrg@mail.gmail.com
2026-04-06 02:12:55 +03:00

89 lines
2.9 KiB
C

/*-------------------------------------------------------------------------
*
* ipc.h
* 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) 1996-2026, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/storage/ipc.h
*
*-------------------------------------------------------------------------
*/
#ifndef IPC_H
#define IPC_H
typedef void (*pg_on_exit_callback) (int code, Datum arg);
typedef void (*shmem_startup_hook_type) (void);
/*----------
* API for handling cleanup that must occur during either ereport(ERROR)
* or ereport(FATAL) exits from a block of code. (Typical examples are
* undoing transient changes to shared-memory state.)
*
* PG_ENSURE_ERROR_CLEANUP(cleanup_function, arg);
* {
* ... code that might throw ereport(ERROR) or ereport(FATAL) ...
* }
* PG_END_ENSURE_ERROR_CLEANUP(cleanup_function, arg);
*
* where the cleanup code is in a function declared per pg_on_exit_callback.
* The Datum value "arg" can carry any information the cleanup function
* needs.
*
* This construct ensures that cleanup_function() will be called during
* either ERROR or FATAL exits. It will not be called on successful
* exit from the controlled code. (If you want it to happen then too,
* call the function yourself from just after the construct.)
*
* Note: the macro arguments are multiply evaluated, so avoid side-effects.
*----------
*/
#define PG_ENSURE_ERROR_CLEANUP(cleanup_function, arg) \
do { \
before_shmem_exit(cleanup_function, arg); \
PG_TRY()
#define PG_END_ENSURE_ERROR_CLEANUP(cleanup_function, arg) \
cancel_before_shmem_exit(cleanup_function, arg); \
PG_CATCH(); \
{ \
cancel_before_shmem_exit(cleanup_function, arg); \
cleanup_function (0, arg); \
PG_RE_THROW(); \
} \
PG_END_TRY(); \
} while (0)
/* ipc.c */
extern PGDLLIMPORT bool proc_exit_inprogress;
extern PGDLLIMPORT bool shmem_exit_inprogress;
pg_noreturn extern void proc_exit(int code);
extern void shmem_exit(int code);
extern void on_proc_exit(pg_on_exit_callback function, Datum arg);
extern void on_shmem_exit(pg_on_exit_callback function, Datum arg);
extern void before_shmem_exit(pg_on_exit_callback function, Datum arg);
extern void cancel_before_shmem_exit(pg_on_exit_callback function, Datum arg);
extern void on_exit_reset(void);
extern void check_on_shmem_exit_lists_are_empty(void);
/* ipci.c */
extern PGDLLIMPORT shmem_startup_hook_type shmem_startup_hook;
extern void RegisterBuiltinShmemCallbacks(void);
extern Size CalculateShmemSize(void);
extern void CreateSharedMemoryAndSemaphores(void);
#ifdef EXEC_BACKEND
extern void AttachSharedMemoryStructs(void);
#endif
extern void InitializeShmemGUCs(void);
#endif /* IPC_H */