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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 performs the same action, 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() and pthread_rwlock_trywrlock() functions will return zero.
     Otherwise, an error number will be returned  to indicate the error.

SEE ALSO
     pthread_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