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pthread_rwlock_unlock(3) [osf1 man page]

pthread_rwlock_unlock(3)				     Library Functions Manual					  pthread_rwlock_unlock(3)

NAME
pthread_rwlock_unlock - Unlock a read-write lock. LIBRARY
DECthreads POSIX 1003.1c Library (libpthread.so) SYNOPSIS
#include <pthread.h> int pthread_rwlock_unlock( pthread_rwlock_t *rwlock); PARAMETERS
Address of the read-write lock to be unlocked. DESCRIPTION
This routine releases a lock acquisition held on the read-write lock object referenced by rwlock. Results are undefined if rwlock is not held by the calling thread. If this routine is called to release a lock for read access on rwlock and the calling thread also currently holds other locks for read access on rwlock, the read-write lock object remains in the read locked state. If this routine releases the calling thread's last lock for read access on rwlock, the calling thread is not longer one of the owners of the lock object. If this routine is called to release a lock for write access on rwlock, the lock object is put in the unlocked state with no owners. If a call to this routine results in the read-write lock object becoming unlocked and there are multiple thread waiting to acquire that lock for write access, DECthreads uses the scheduling policy of those waiting threads to determine which thread next acquires the lock object for write access. If there are multiple thread waiting to acquire the read-write lock object for read access, DECthreads uses the scheduling policy of those waiting threads to determine the order in which those threads acquire the lock for read access. If there are multiple threads waiting to acquire the read-write lock object for both read and write access, it is unspecified whether a thread waiting for read access or for write access next acquires the lock object. If the read-write lock object referenced by rwlock is not initialized, the results of calling this routine are undefined. RETURN VALUES
If an error condition occurs, this routine returns an integer value indicating the type of error. Possible return values are as follows: Successful completion. The values specified by rwlock does not refer to an initialized read-write lock object. The current thread does not hold the read-write lock object. ERRORS
None RELATED INFORMATION
Functions: pthread_rwlock_init(3), pthread_rwlock_rdlock(3), pthread_rwlock_wrlock(3), pthread_rwlockattr_init(3) Manuals: Guide to DECthreads and Programmer's Guide delim off pthread_rwlock_unlock(3)

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pthread_rwlock_tryrdlock(3)				     Library Functions Manual				       pthread_rwlock_tryrdlock(3)

NAME
pthread_rwlock_tryrdlock - Attempts to acquire a read-write lock for read access without waiting. LIBRARY
DECthreads POSIX 1003.1c Library (libpthread.so) SYNOPSIS
#include <pthread.h> int pthread_rwlock_tryrdlock( pthread_rwlock_t *rwlock); PARAMETERS
Address of the read-write lock object to acquire for read access. DESCRIPTION
This routine attempts to acquire a read-write lock for read access, but does not wait for the lock if it not immediately available. If a thread already holds the lock for read access, the lock is granted and this routine returns. If no thread already holds the lock for write access and there are no writers waiting to acquire the lock, the lock for read access is granted to the calling thread and this rou- tine returns. If some thread already holds the lock for write access, the calling thread will not acquire the read lock. Results are undefined if the calling thread has already acquired a lock for write access on rwlock when this routine is called. A thread can hold multiple, concurrent locks for read access on the same read-write lock. In a given thread, for each call to this routine that successfully acquires the same read-write lock for read access, a corrresponding call to pthread_rwlock_unlock must be issued. If the read-write lock object referenced by rwlock is not initialized, the results of calling this routine are undefined. RETURN VALUES
If an error condition occurs, this routine returns an integer value indicating the type of error. Possible return values are as follows: Successful completion. The read-write lock could not be acquired for read access because another thread already acquired it for write access or is blocked and waiting for it for write access. The value specified by rwlock does not refer to an initialized read-write lock object. The current thread already owns the read-write lock for writing. The lock for read access could not be acquired because the maxi- mum number of read lock acquisitions for rwlock has been exceeded. ERRORS
None RELATED INFORMATION
Functions: pthread_rwlock_init(3), pthread_rwlockattr_init(3), pthread_rwlock_rdlock(3), pthread_rwlock_wrlock(3), pthread_rwlock_unlock(3) Manuals: Guide to DECthreads and Programmer's Guide delim off pthread_rwlock_tryrdlock(3)
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