pthread_rwlock_unlock(3c) [opensolaris man page]

pthread_rwlock_unlock(3C)				   Standard C Library Functions 				 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);

DESCRIPTION

       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.

RETURN VALUES

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

ATTRIBUTES

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

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

SEE ALSO

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

SunOS 5.11							    23 Mar 2005 					 pthread_rwlock_unlock(3C)

Check Out this Related Man Page

pthread_rwlock_rdlock(3)				     Library Functions Manual					  pthread_rwlock_rdlock(3)

NAME

       pthread_rwlock_rdlock - Acquires a read-write lock for read access.

LIBRARY

       DECthreads POSIX 1003.1c Library (libpthread.so)

SYNOPSIS

       #include <pthread.h>

       int   pthread_rwlock_rdlock(
			     pthread_rwlock_t	      *rwlock);

PARAMETERS

       Address of the read-write lock object to acquire for read access.

DESCRIPTION

       This  routine  acquires	a  read-write lock for read access.  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 routine returns.  If a thread already holds
       the lock for read access, the lock is granted and this routine returns.

       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 corresponding call to pthread_rwlock_unlock must be issued.

       If some thread already holds the lock for write access, the calling thread will not acquire the	read  lock.   If  the  read  lock  is  not
       acquired,  the calling thread blocks until it can acquire the lock for read access. Results are undefined if the calling thread has already
       acquired a lock for write access on rwlock when this routine is called.

       If the read-write lock object referenced by rwlock is not initialized, the results of calling this routine are undefined.

       If a thread is interrupted (via a Tru64 UNIX signal or an OpenVMS AST) while waiting for a read-write lock for  read  access,  upon  return
       from the interrupt routine the thread resumes waiting for the lock as if it had not been interrupted.

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 lock for read access could not be acquired because the maximum number of read lock acquisitions for rwlock  has
       been  exceeded.	 The current thread already owns the read-write lock for writing.  The value specified by rwlock does not refer to an ini-
       tialized read-write lock object.

ERRORS

       None

RELATED INFORMATION

       Functions:      pthread_rwlock_init(3),	    pthread_rwlockattr_init(3),       pthread_rwlock_tryrdlock(3),	 pthread_rwlock_wrlock(3),
       pthread_rwlock_unlock(3)

       Manuals: Guide to DECthreads and Programmer's Guide

       delim off

															  pthread_rwlock_rdlock(3)

Linux and UNIX Man Pages

pthread_rwlock_unlock(3c) [opensolaris man page]

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