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b2307f8e31
postmaster startup scrutinizes any shared memory segment recorded in postmaster.pid, exiting if that segment matches the current data directory and has an attached process. When the postmaster.pid file was missing, a starting postmaster used weaker checks. Change to use the same checks in both scenarios. This increases the chance of a startup failure, in lieu of data corruption, if the DBA does "kill -9 `head -n1 postmaster.pid` && rm postmaster.pid && pg_ctl -w start". A postmaster will no longer recycle segments pertaining to other data directories. That's good for production, but it's bad for integration tests that crash a postmaster and immediately delete its data directory. Such a test now leaks a segment indefinitely. No "make check-world" test does that. win32_shmem.c already avoided all these problems. In 9.6 and later, enhance PostgresNode to facilitate testing. Back-patch to 9.4 (all supported versions). Reviewed by Daniel Gustafsson and Kyotaro HORIGUCHI. Discussion: https://postgr.es/m/20130911033341.GD225735@tornado.leadboat.com
82 lines
2.7 KiB
C
82 lines
2.7 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) 1996-2018, 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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* src/include/storage/ipc.h
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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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typedef void (*shmem_startup_hook_type) (void);
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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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before_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_before_shmem_exit(cleanup_function, arg); \
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PG_CATCH(); \
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{ \
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cancel_before_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 PGDLLIMPORT bool proc_exit_inprogress;
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extern PGDLLIMPORT bool shmem_exit_inprogress;
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extern void proc_exit(int code) pg_attribute_noreturn();
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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 before_shmem_exit(pg_on_exit_callback function, Datum arg);
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extern void cancel_before_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 PGDLLIMPORT shmem_startup_hook_type shmem_startup_hook;
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extern void CreateSharedMemoryAndSemaphores(int port);
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#endif /* IPC_H */
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