PTHREAD_RWLOCK_WRLOCK(3) OpenBSD Programmer's Manual PTHREAD_RWLOCK_WRLOCK(3)NAME
pthread_rwlock_wrlock, pthread_rwlock_timedwrlock,
pthread_rwlock_trywrlock - acquire a read/write lock for writing
SYNOPSIS
#include <pthread.h>
int
pthread_rwlock_wrlock(pthread_rwlock_t *lock);
int
pthread_rwlock_timedwrlock(pthread_rwlock_t *lock, const struct timespec
*abstime);
int
pthread_rwlock_trywrlock(pthread_rwlock_t *lock);
DESCRIPTION
The pthread_rwlock_wrlock() function blocks until a write lock can be
acquired against lock.
The pthread_rwlock_timedwrlock() function performs the same action, but
will not wait beyond abstime to obtain the lock before returning.
The pthread_rwlock_trywrlock() function performs the same action as
pthread_rwlock_wrlock(), but does not block if the lock cannot be
immediately obtained.
The results are undefined if the calling thread already holds the lock at
the time the call is made.
IMPLEMENTATION NOTES
To prevent writer starvation, writers are favored over readers.
RETURN VALUES
If successful, the pthread_rwlock_wrlock(), pthread_rwlock_timedwrlock(),
and pthread_rwlock_trywrlock() functions will return zero. Otherwise an
error number will be returned to indicate the error.
ERRORS
The pthread_rwlock_trywrlock() function will fail if:
[EBUSY] The calling thread is not able to acquire the lock without
blocking.
The pthread_rwlock_timedwrlock() function will fail if:
[ETIMEDOUT] The time specified by abstime was reached before the lock
could be obtained.
The pthread_rwlock_wrlock(), pthread_rwlock_timedwrlock(), and
pthread_rwlock_trywrlock() functions may fail if:
[EDEADLK] The calling thread already owns the read/write lock (for
reading or writing).
[EINVAL] The value specified by lock is invalid.
[ENOMEM] Insufficient memory exists to initialize the lock (applies
to statically initialized locks only).
SEE ALSOpthread_rwlock_unlock(3)STANDARDS
The pthread_rwlock_wrlock(), pthread_rwlock_timedwrlock(), and
pthread_rwlock_trywrlock() functions are expected to conform to Version 2
of the Single UNIX Specification.
HISTORY
The pthread_rwlock_wrlock() function first appeared in FreeBSD 3.0 and
OpenBSD 2.5. The pthread_rwlock_timedwrlock() function first appeared in
OpenBSD 4.8.
OpenBSD 4.9 May 3, 2010 OpenBSD 4.9
