PTHREAD_RWLOCK_WRLOCK(3) BSD Library Functions Manual PTHREAD_RWLOCK_WRLOCK(3)NAME
pthread_rwlock_trywrlock, pthread_rwlock_wrlock — acquire a read/write
lock for writing
SYNOPSIS
#include <pthread.h>
int
pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);
int
pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);
DESCRIPTION
The pthread_rwlock_wrlock() function blocks until a write lock can be
acquired against rwlock. The pthread_rwlock_trywrlock() function per‐
forms the same action, but does not block if the lock cannot be immedi‐
ately 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() and pthread_rwlock_trywrlock()
functions will return zero. Otherwise, an error number will be returned
to indicate the error.
SEE ALSOpthread_rwlock_trywrlock(3), pthread_rwlock_unlock(3),
pthread_rwlock_wrlock(3)STANDARDS
The pthread_rwlock_wrlock() and pthread_rwlock_trywrlock() functions are
expected to conform to Version 2 of the Single UNIX Specification
(“SUSv2”).
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_wrlock() 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 rwlock is invalid.
[ENOMEM] Insufficient memory exists to initialize the lock
(applies to statically initialized locks only).
HISTORY
The pthread_rwlock_wrlock() function first appeared in FreeBSD 3.0.
BSD August 4, 1998 BSD
