pthread_rwlock_unlock(3c) [sunos man page]

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)

Check Out this Related Man Page

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)

Linux and UNIX Man Pages

pthread_rwlock_unlock(3c) [sunos man page]

Check Out this Related Man Page