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PTHREAD_RWLOCK_WRLOCK(3) BSD Library Functions Manual PTHREAD_RWLOCK_WRLOCK(3) NAME pthread_rwlock_trywrlock, pthread_rwlock_wrlock -- acquire a read/write lock for writing SYNOPSIS #include <pthread.h> int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock); int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock); DESCRIPTION The pthread_rwlock_wrlock() function blocks until a write lock can be acquired against rwlock. The pthread_rwlock_trywrlock() function per-forms performs forms the same action, but does not block if the lock cannot be immedi-ately immediately ately obtained. The results are undefined if the calling thread already holds the lock at the time the call is made. IMPLEMENTATION NOTES To prevent writer starvation, writers are favored over readers. RETURN VALUES If successful, the pthread_rwlock_wrlock() and pthread_rwlock_trywrlock() functions will return zero. Otherwise, an error number will be returned to indicate the error. SEE ALSO pthread_rwlock_trywrlock(3), pthread_rwlock_unlock(3), pthread_rwlock_wrlock(3) STANDARDS The pthread_rwlock_wrlock() and pthread_rwlock_trywrlock() functions are expected to conform to Version 2 of the Single UNIX Specification (``SUSv2''). ERRORS The pthread_rwlock_trywrlock() function will fail if: [EBUSY] The calling thread is not able to acquire the lock without blocking. The pthread_rwlock_wrlock() and pthread_rwlock_trywrlock() functions may fail if: [EDEADLK] The calling thread already owns the read/write lock (for reading or writing). [EINVAL] The value specified by rwlock is invalid. [ENOMEM] Insufficient memory exists to initialize the lock (applies to statically initialized locks only). HISTORY The pthread_rwlock_wrlock() function first appeared in FreeBSD 3.0. BSD August 4, 1998 BSD |