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pthread_rwlock_unlock

Section: C Library Functions (3)
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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

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Index

NAME
LIBRARY
SYNOPSIS
PARAMETERS
DESCRIPTION
RETURN VALUES
ERRORS
RELATED INFORMATION

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Time: 02:41:35 GMT, October 02, 2010