pthread_rwlock_unlock(3C)                                                                                                pthread_rwlock_unlock(3C)

NAME

       pthread_rwlock_unlock - unlock read-write lock object

SYNOPSIS

       cc -mt [ flag... ] file... -lpthread [ library... ]
       #include <pthread.h>

       int pthread_rwlock_unlock(pthread_rwlock_t *rwlock);

       The pthread_rwlock_unlock() function is called to release a lock held on the read-write lock object referenced by rwlock. Results are unde-
       fined if the read-write lock rwlock is not held by the calling thread.

       If this function is called to release a read lock from the read-write lock object and there are other read locks  currently  held  on  this
       read-write  lock  object,  the read-write lock object remains in the read locked state. If this function releases the calling thread's last
       read lock on this read-write lock object, then the calling thread is no longer one of the owners of the object. If this  function  releases
       the last read lock for this read-write lock object, the read-write lock object will be put in the unlocked state with no owners.

       If  this function is called to release a write lock for this read-write lock object, the read-write lock object will be put in the unlocked
       state with no owners.

       If the call to the pthread_rwlock_unlock() function results in the read-write lock object becoming unlocked and there are multiple  threads
       waiting  to acquire the read-write lock object for writing, the scheduling policy is used to determine which thread acquires the read-write
       lock object for writing. If there are multiple threads waiting to acquire the read-write lock object for reading, the scheduling policy  is
       used  to  determine  the  order in which the waiting threads acquire the read-write lock object for reading.  If there are multiple threads
       blocked on rwlock for both read locks and write locks, it is unspecified whether the readers acquire the lock first  or  whether  a  writer
       acquires the lock first.

       Results are undefined if any of these functions are called with an uninitialized read-write lock.

       If successful, the pthread_rwlock_unlock() function returns 0. Otherwise, an error number is returned to indicate the error.

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE         |      ATTRIBUTE VALUE        |
       +-----------------------------+-----------------------------+
       |Interface Stability          |Standard                     |
       +-----------------------------+-----------------------------+
       |MT-Level                     |MT-Safe                      |
       +-----------------------------+-----------------------------+

       pthread_rwlock_init(3C), pthread_rwlock_rdlock(3C), pthread_rwlock_wrlock(3C), pthread_rwlockattr_init(3C), attributes(5), standards(5)

                                                                    23 Mar 2005                                          pthread_rwlock_unlock(3C)