NetBSD-5.0.2/lib/libpthread/pthread_rwlock_wrlock.3

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.\" $NetBSD: pthread_rwlock_wrlock.3,v 1.8 2008/05/04 19:43:05 martin Exp $
.\"
.\" Copyright (c) 2002 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" Copyright (c) 1998 Alex Nash
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.\" 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.
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.\" 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)
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.\" $FreeBSD: src/lib/libpthread/man/pthread_rwlock_wrlock.3,v 1.5 2002/09/16 19:29:29 mini Exp $
.\"
.Dd January 30, 2003
.Dt PTHREAD_RWLOCK_WRLOCK 3
.Os
.Sh NAME
.Nm pthread_rwlock_wrlock ,
.Nm pthread_rwlock_timedwrlock ,
.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_timedwrlock "pthread_rwlock_t * restrict lock" "const struct timespec * restrict abstime"
.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 .
.Pp
The
.Fn pthread_rwlock_timedwrlock
performs the same action, but will not wait beyond
.Fa abstime
to obtain the lock before returning.
.Pp
The
.Fn pthread_rwlock_trywrlock
function performs the same action as
.Fn pthread_rwlock_wrlock ,
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 RETURN VALUES
If successful, the
.Fn pthread_rwlock_wrlock ,
.Fn pthread_rwlock_timedwrlock ,
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 shall 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_timedrdlock
function shall fail if:
.Bl -tag -width Er
.It Bq Er ETIMEDOUT
The time specified by
.Fa abstime
was reached before the lock could be obtained.
.El
.Pp
The
.Fn pthread_rwlock_wrlock ,
.Fn pthread_rwlock_timedwrlock ,
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.
.El
.Sh SEE ALSO
.Xr pthread_rwlock_destroy 3 ,
.Xr pthread_rwlock_init 3 ,
.Xr pthread_rwlock_rdlock 3 ,
.Xr pthread_rwlock_unlock 3
.Sh STANDARDS
.Fn pthread_rwlock_wrlock ,
.Fn pthread_rwlock_timedwrlock ,
 and
.Fn pthread_rwlock_trywrlock
conform to
.St -p1003.1-96 .