NAME    [Toc]    [Back]

       pthread_rwlock_unlock - Unlock a read-write lock

SYNOPSIS    [Toc]    [Back]

       #include <pthread.h>

       int pthread_rwlock_unlock(
               pthread_rwlock_t *rwlock );

LIBRARY    [Toc]    [Back]

       DECthreads POSIX 1003.1c Library (libpthread.so)

PARAMETERS    [Toc]    [Back]

       Address of the read-write lock to be unlocked.

DESCRIPTION    [Toc]    [Back]

       This routine releases a lock acquisition held on the readwrite
 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 readwrite
 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    [Toc]    [Back]

       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    [Toc]    [Back]

       None

SEE ALSO    [Toc]    [Back]

       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



                                         pthread_rwlock_unlock(3)