korsygfhrtzangaiide

/*------------------------------------------------------------------------- * * pg_sema.h * Platform-independent API for semaphores. * * PostgreSQL requires counting semaphores (the kind that keep track of * multiple unlock operations, and will allow an equal number of subsequent * lock operations before blocking). The underlying implementation is * not the same on every platform. This file defines the API that must * be provided by each port. * * * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * src/include/storage/pg_sema.h * *------------------------------------------------------------------------- */ #ifndef PG_SEMA_H #define PG_SEMA_H /* * PGSemaphoreData and pointer type PGSemaphore are the data structure * representing an individual semaphore. The contents of PGSemaphoreData * vary across implementations and must never be touched by platform- * independent code. PGSemaphoreData structures are always allocated * in shared memory (to support implementations where the data changes during * lock/unlock). * * pg_config.h must define exactly one of the USE_xxx_SEMAPHORES symbols. */ #ifdef USE_NAMED_POSIX_SEMAPHORES #include <semaphore.h> typedef sem_t *PGSemaphoreData; #endif #ifdef USE_UNNAMED_POSIX_SEMAPHORES #include <semaphore.h> typedef sem_t PGSemaphoreData; #endif #ifdef USE_SYSV_SEMAPHORES typedef struct PGSemaphoreData { int semId; /* semaphore set identifier */ int semNum; /* semaphore number within set */ } PGSemaphoreData; #endif #ifdef USE_WIN32_SEMAPHORES typedef HANDLE PGSemaphoreData; #endif typedef PGSemaphoreData *PGSemaphore; /* Module initialization (called during postmaster start or shmem reinit) */ extern void PGReserveSemaphores(int maxSemas, int port); /* Initialize a PGSemaphore structure to represent a sema with count 1 */ extern void PGSemaphoreCreate(PGSemaphore sema); /* Reset a previously-initialized PGSemaphore to have count 0 */ extern void PGSemaphoreReset(PGSemaphore sema); /* Lock a semaphore (decrement count), blocking if count would be < 0 */ extern void PGSemaphoreLock(PGSemaphore sema, bool interruptOK); /* Unlock a semaphore (increment count) */ extern void PGSemaphoreUnlock(PGSemaphore sema); /* Lock a semaphore only if able to do so without blocking */ extern bool PGSemaphoreTryLock(PGSemaphore sema); #endif /* PG_SEMA_H */