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

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														       pthread_rwlock_tryrdlock(3)

Linux and UNIX Man Pages

pthread_rwlock_unlock(3) [osf1 man page]

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