pthread_rwlock_tryrdlock(3)pthread_rwlock_tryrdlock(3)NAMEpthread_rwlock_tryrdlock - Attempts to acquire a read-write lock for
read access without waiting
SYNOPSIS
#include <pthread.h>
int pthread_rwlock_tryrdlock(
pthread_rwlock_t *rwlock );
LIBRARY
DECthreads POSIX 1003.1c Library (libpthread.so)
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 routine
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
corresponding 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 maximum number of
read lock acquisitions for rwlock has been exceeded.
ERRORS
None
SEE ALSO
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
pthread_rwlock_tryrdlock(3)