pthread_rwlock_timedrdlock(3C)				   Standard C Library Functions 			    pthread_rwlock_timedrdlock(3C)

NAME

       pthread_rwlock_timedrdlock, pthread_rwlock_reltimedrdlock_np - lock a read-write lock for reading

SYNOPSIS

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

       int pthread_rwlock_timedrdlock(pthread_rwlock_t *restrict rwlock,
	    const struct timespec *restrict abs_timeout);

       int pthread_rwlock_reltimedrdlock_np(pthread_rwlock_t *restrict rwlock,
	    const struct timespec *restrict rel_timeout);

DESCRIPTION

       The   pthread_rwlock_timedrdlock()   function   applies	 a   read   lock   to	the  read-write  lock  referenced  by  rwlock  as  in  the
       pthread_rwlock_rdlock(3C) function. If the lock cannot be acquired without waiting for other threads to unlock the lock, this wait will	be
       terminated  when  the specified timeout expires. The timeout expires when the absolute time specified by abs_timeout passes, as measured by
       the CLOCK_REALTIME clock (that is, when the value of that clock equals or exceeds abs_timeout),	or  if	the  absolute  time  specified	by
       abs_timeout has already been passed at the time of the call.

       The pthread_rwlock_reltimedrdlock_np() function is identical to the pthread_rwlock_timedrdlock() function, except that the timeout is spec-
       ified as a relative time interval.  The timeout expires when the time  interval	specified  by  rel_timeout  passes,  as  measured  by  the
       CLOCK_REALTIME clock, or if the time interval specified by rel_timeout is negative at the time of the call.

       The  resolution	of  the  timeout  is the resolution of the CLOCK_REALTIME clock. The timespec data type is defined in the <time.h> header.
       Under no circumstances does either function fail with a timeout if the lock can be acquired immediately. The validity of the timeout param-
       eter need not be checked if the lock can be immediately acquired.

       If  a  signal  that  causes  a  signal  handler	to  be	executed  is  delivered  to  a	thread blocked on a read-write lock with a call to
       pthread_rwlock_timedrdlock() or pthread_rwlock_reltimedrdlock_np(), upon return from the signal handler the thread resumes waiting for  the
       lock as if it was not interrupted.

       The calling thread might deadlock if at the time the call is made it holds a write lock on rwlock.

       The results are undefined if this function is called with an uninitialized read-write lock.

RETURN VALUES

       The  pthread_rwlock_timedrdlock()  and pthread_rwlock_reltimedrdlock_np() functions return 0 if the lock for reading 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_timedrdlock() and and pthread_rwlock_reltimedrdlock_np() functions will fail if:

       ETIMEDOUT     The lock could not be acquired before the specified timeout expired.

       The pthread_rwlock_timedrdlock() and pthread_rwlock_reltimedrdlock_np() functions may fail if:

       EAGAIN	  The read lock could not be acquired because the maximum number of read locks for lock would be exceeded.

       EDEADLK	  The calling thread already holds a write lock on rwlock.

       EINVAL	  The value specified by rwlock does not refer to an initialized read-write lock object, or the timeout nanosecond value  is  less
		  than zero or greater than or equal to 1 000 million.

ATTRIBUTES

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

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |See below.		   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

       The pthread_rwlock_timedrdlock() function is Standard. The pthread_rwlock_reltimedrdlock_np() is Stable.

SEE ALSO

       pthread_rwlock_destroy(3C),	   pthread_rwlock_rdlock(3C),	      pthread_rwlock_timedwrlock(3C),	     pthread_rwlock_trywrlock(3C),
       pthread_rwlock_unlock(3C), pthread_rwlock_wrlock(3C), attributes(5), standards(5)

SunOS 5.11							    30 Jan 2004 				    pthread_rwlock_timedrdlock(3C)