mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-27 11:55:06 +00:00
107 lines
3.2 KiB
Groff
107 lines
3.2 KiB
Groff
.\" Copyright (c) 1998 Alex Nash
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd August 4, 1998
|
|
.Dt PTHREAD_RWLOCK_WRLOCK 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm pthread_rwlock_wrlock ,
|
|
.Nm pthread_rwlock_trywrlock
|
|
.Nd acquire a read/write lock for writing
|
|
.Sh LIBRARY
|
|
.Lb libpthread
|
|
.Sh SYNOPSIS
|
|
.In pthread.h
|
|
.Ft int
|
|
.Fn pthread_rwlock_wrlock "pthread_rwlock_t *lock"
|
|
.Ft int
|
|
.Fn pthread_rwlock_trywrlock "pthread_rwlock_t *lock"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn pthread_rwlock_wrlock
|
|
function blocks until a write lock can be acquired against
|
|
.Fa lock .
|
|
The
|
|
.Fn pthread_rwlock_trywrlock
|
|
function performs the same action, but does not block if the lock
|
|
cannot be immediately obtained.
|
|
.Pp
|
|
The results are undefined if the calling thread already holds the
|
|
lock at the time the call is made.
|
|
.Sh IMPLEMENTATION NOTES
|
|
To prevent writer starvation, writers are favored over readers.
|
|
.Sh RETURN VALUES
|
|
If successful, the
|
|
.Fn pthread_rwlock_wrlock
|
|
and
|
|
.Fn pthread_rwlock_trywrlock
|
|
functions will return zero.
|
|
Otherwise an error number will be returned
|
|
to indicate the error.
|
|
.Sh ERRORS
|
|
The
|
|
.Fn pthread_rwlock_trywrlock
|
|
function will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EBUSY
|
|
The calling thread is not able to acquire the lock without blocking.
|
|
.El
|
|
.Pp
|
|
The
|
|
.Fn pthread_rwlock_wrlock
|
|
and
|
|
.Fn pthread_rwlock_trywrlock
|
|
functions may fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EDEADLK
|
|
The calling thread already owns the read/write lock (for reading
|
|
or writing).
|
|
.It Bq Er EINVAL
|
|
The value specified by
|
|
.Fa lock
|
|
is invalid.
|
|
.It Bq Er ENOMEM
|
|
Insufficient memory exists to initialize the lock (applies to
|
|
statically initialized locks only).
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr pthread_rwlock_init 3 ,
|
|
.Xr pthread_rwlock_rdlock 3 ,
|
|
.Xr pthread_rwlock_tryrdlock 3 ,
|
|
.Xr pthread_rwlock_unlock 3
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn pthread_rwlock_wrlock
|
|
and
|
|
.Fn pthread_rwlock_trywrlock
|
|
functions are expected to conform to
|
|
.St -susv2 .
|
|
.Sh HISTORY
|
|
The
|
|
.Fn pthread_rwlock_wrlock
|
|
function first appeared in
|
|
.Fx 3.0 .
|