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/*-------------------------------------------------------------------------
*
* 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) 1996-2022, 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;
extern void proc_exit(int code) pg_attribute_noreturn();
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 Size CalculateShmemSize(int *num_semaphores);
extern void CreateSharedMemoryAndSemaphores(void);
extern void InitializeShmemGUCs(void);
#endif /* IPC_H */
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