pthread_rwlock_wrlock(3C)				   Standard C Library Functions 				 pthread_rwlock_wrlock(3C)

NAME

       pthread_rwlock_wrlock, pthread_rwlock_trywrlock - lock or attempt to lock read-write lock object for writing

SYNOPSIS

       cc -mt [ flag... ] file... -lpthread [ library... ]
       #include <pthread.h>

       int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);

       int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);

DESCRIPTION

       The  pthread_rwlock_wrlock()  function  applies	a  write lock to the read-write lock referenced by rwlock. The calling thread acquires the
       write lock if no other thread (reader or writer) holds the read-write lock rwlock. Otherwise, the thread blocks until it  can  acquire  the
       lock.

       The  pthread_rwlock_trywrlock()	function applies a write lock like the pthread_rwlock_wrlock() function, with the exception that the func-
       tion fails if any thread currently holds rwlock (for reading or writing).

       Writers are favored over readers of the same priority to avoid writer starvation. See pthread_rwlock_rdlock(3C).

       Results are undefined if any of these functions are called with an uninitialized read-write lock.

       If a signal is delivered to a thread waiting for a read-write lock for writing, upon return from the  signal  handler  the  thread  resumes
       waiting for the read-write lock for writing as if it was not interrupted.

RETURN VALUES

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

       The  pthread_rwlock_trywrlock()	function returns 0 if the lock for writing on the read-write lock object referenced by rwlock is acquired.
       Otherwise an error number is returned to indicate the error.

ERRORS

       The pthread_rwlock_wrlock() function will fail if:

       EDEADLK	  The current thread already owns the read-write lock for writing or reading.

       The pthread_rwlock_trywrlock() function will fail if:

       EBUSY	The read-write lock could not be acquired for writing because it was already locked for reading or writing.

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_unlock(3C), pthread_rwlockattr_init(3C), pthread_rwlock_rdlock(3C), attributes(5), standards(5)

SunOS 5.11							    23 Mar 2005 					 pthread_rwlock_wrlock(3C)