freebsd man page for pthread_rwlock_timedrdlock

PTHREAD_RWLOCK_TIMEDRDLOCK(3)				   BSD Library Functions Manual 			     PTHREAD_RWLOCK_TIMEDRDLOCK(3)

NAME
     pthread_rwlock_timedrdlock -- acquire a read-write lock for reading or give up after a specified period

LIBRARY
     POSIX Threads Library (libpthread, -lpthread)

SYNOPSIS
     #include <pthread.h>

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

DESCRIPTION
     This function acquires a read lock on the read-write lock rwlock.	However, if the lock cannot be acquired without waiting for another thread
     to unlock the lock, this wait shall be terminated when abs_timeout expires.

     A thread may hold multiple concurrent read locks.	The pthread_rwlock_unlock(3) function must be called once for each lock acquired.

     If the thread should be interrupted by a signal, the pthread_rwlock_timedrdlock() function will be automatically restarted after the thread
     returns from the signal handler.

     The calling thread may 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.

IMPLEMENTATION NOTES
     To prevent writer starvation, writers are favored over readers.

RETURN VALUES
     If successful, the pthread_rwlock_timedrdlock() function will return zero.  Otherwise, an error number will be returned to indicate the
     error.

     This function shall not return an error code of EINTR.

ERRORS
     The pthread_rwlock_timedrdlock() function will fail if:

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

     The pthread_rwlock_timedrdlock() function may fail if:

     [EAGAIN]		The read lock could not be acquired because the maximum number of read locks for rwlock 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 abs_timeout nanosecond value
			is less than zero or greater than or equal to 1 billion.

SEE ALSO
     pthread_rwlock_init(3), pthread_rwlock_timedwrlock(3), pthread_rwlock_unlock(3)

STANDARDS
     The pthread_rwlock_timedrdlock() function is expected to conform to ISO/IEC 9945-1:1996 (``POSIX.1'').

HISTORY
     The pthread_rwlock_timedrdlock() function first appeared in FreeBSD 5.2.

BSD
								 January 16, 2004							       BSD