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d06995710b
The remaining caller (lwlocks) doesn't need that facility, and we plan to remove ImmedidateInterruptOK entirely. That means that interrupts can't be serviced race-free and portably anyway, so there's little reason for keeping the feature. Reviewed-By: Heikki Linnakangas
84 lines
2.4 KiB
C
84 lines
2.4 KiB
C
/*-------------------------------------------------------------------------
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*
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* pg_sema.h
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* Platform-independent API for semaphores.
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*
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* PostgreSQL requires counting semaphores (the kind that keep track of
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* multiple unlock operations, and will allow an equal number of subsequent
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* lock operations before blocking). The underlying implementation is
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* not the same on every platform. This file defines the API that must
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* be provided by each port.
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*
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*
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* Portions Copyright (c) 1996-2015, 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/pg_sema.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PG_SEMA_H
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#define PG_SEMA_H
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/*
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* PGSemaphoreData and pointer type PGSemaphore are the data structure
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* representing an individual semaphore. The contents of PGSemaphoreData
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* vary across implementations and must never be touched by platform-
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* independent code. PGSemaphoreData structures are always allocated
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* in shared memory (to support implementations where the data changes during
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* lock/unlock).
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*
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* pg_config.h must define exactly one of the USE_xxx_SEMAPHORES symbols.
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*/
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#ifdef USE_NAMED_POSIX_SEMAPHORES
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#include <semaphore.h>
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typedef sem_t *PGSemaphoreData;
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#endif
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#ifdef USE_UNNAMED_POSIX_SEMAPHORES
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#include <semaphore.h>
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typedef sem_t PGSemaphoreData;
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#endif
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#ifdef USE_SYSV_SEMAPHORES
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typedef struct PGSemaphoreData
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{
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int semId; /* semaphore set identifier */
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int semNum; /* semaphore number within set */
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} PGSemaphoreData;
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#endif
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#ifdef USE_WIN32_SEMAPHORES
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typedef HANDLE PGSemaphoreData;
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#endif
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typedef PGSemaphoreData *PGSemaphore;
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/* Module initialization (called during postmaster start or shmem reinit) */
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extern void PGReserveSemaphores(int maxSemas, int port);
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/* Initialize a PGSemaphore structure to represent a sema with count 1 */
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extern void PGSemaphoreCreate(PGSemaphore sema);
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/* Reset a previously-initialized PGSemaphore to have count 0 */
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extern void PGSemaphoreReset(PGSemaphore sema);
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/* Lock a semaphore (decrement count), blocking if count would be < 0 */
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extern void PGSemaphoreLock(PGSemaphore sema);
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/* Unlock a semaphore (increment count) */
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extern void PGSemaphoreUnlock(PGSemaphore sema);
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/* Lock a semaphore only if able to do so without blocking */
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extern bool PGSemaphoreTryLock(PGSemaphore sema);
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#endif /* PG_SEMA_H */
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