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corrupted. (Neither is very important if SIGTERM is used to shut down the whole database cluster together, but there's a problem if someone tries to SIGTERM individual backends.) To do this, introduce new infrastructure macros PG_ENSURE_ERROR_CLEANUP/PG_END_ENSURE_ERROR_CLEANUP that take care of transiently pushing an on_shmem_exit cleanup hook. Also use this method for createdb cleanup --- that wasn't a shared-memory-corruption problem, but SIGTERM abort of createdb could leave orphaned files lying around. Backpatch as far as 8.2. The shmem corruption cases don't exist in 8.1, and the createdb usage doesn't seem important enough to risk backpatching further.
77 lines
2.5 KiB
C
77 lines
2.5 KiB
C
/*-------------------------------------------------------------------------
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*
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* ipc.h
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* POSTGRES inter-process communication definitions.
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*
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* This file is misnamed, as it no longer has much of anything directly
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* to do with IPC. The functionality here is concerned with managing
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* exit-time cleanup for either a postmaster or a backend.
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*
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*
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* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/storage/ipc.h,v 1.74.2.1 2008/04/16 23:59:51 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef IPC_H
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#define IPC_H
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typedef void (*pg_on_exit_callback) (int code, Datum arg);
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/*----------
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* API for handling cleanup that must occur during either ereport(ERROR)
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* or ereport(FATAL) exits from a block of code. (Typical examples are
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* undoing transient changes to shared-memory state.)
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*
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* PG_ENSURE_ERROR_CLEANUP(cleanup_function, arg);
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* {
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* ... code that might throw ereport(ERROR) or ereport(FATAL) ...
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* }
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* PG_END_ENSURE_ERROR_CLEANUP(cleanup_function, arg);
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*
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* where the cleanup code is in a function declared per pg_on_exit_callback.
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* The Datum value "arg" can carry any information the cleanup function
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* needs.
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*
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* This construct ensures that cleanup_function() will be called during
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* either ERROR or FATAL exits. It will not be called on successful
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* exit from the controlled code. (If you want it to happen then too,
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* call the function yourself from just after the construct.)
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*
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* Note: the macro arguments are multiply evaluated, so avoid side-effects.
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*----------
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*/
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#define PG_ENSURE_ERROR_CLEANUP(cleanup_function, arg) \
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do { \
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on_shmem_exit(cleanup_function, arg); \
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PG_TRY()
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#define PG_END_ENSURE_ERROR_CLEANUP(cleanup_function, arg) \
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cancel_shmem_exit(cleanup_function, arg); \
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PG_CATCH(); \
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{ \
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cancel_shmem_exit(cleanup_function, arg); \
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cleanup_function (0, arg); \
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PG_RE_THROW(); \
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} \
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PG_END_TRY(); \
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} while (0)
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/* ipc.c */
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extern bool proc_exit_inprogress;
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extern void proc_exit(int code);
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extern void shmem_exit(int code);
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extern void on_proc_exit(pg_on_exit_callback function, Datum arg);
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extern void on_shmem_exit(pg_on_exit_callback function, Datum arg);
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extern void cancel_shmem_exit(pg_on_exit_callback function, Datum arg);
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extern void on_exit_reset(void);
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/* ipci.c */
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extern void CreateSharedMemoryAndSemaphores(bool makePrivate, int port);
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#endif /* IPC_H */
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