NetBSD/lib/libpthread/pthread_key_delete.3

.\" $NetBSD: pthread_key_delete.3,v 1.4 2003/07/04 08:42:57 wiz 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
.\" 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.
.\" 3. Neither the name of The NetBSD Foundation nor the names of its
.\"    contributors may be used to endorse or promote products derived
.\"    from this software without specific prior written permission.
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
.\"
.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>.
.\" 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.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by John Birrell.
.\" 4. Neither the name of the author nor the names of any co-contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL 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 REGENTS 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: src/lib/libpthread/man/pthread_key_delete.3,v 1.12 2002/09/16 19:29:28 mini Exp $
.\"
.Dd January 30, 2003
.Dt PTHREAD_KEY_DELETE 3
.Os
.Sh NAME
.Nm pthread_key_delete
.Nd delete a thread-specific data key
.Sh LIBRARY
.Lb libpthread
.Sh SYNOPSIS
.In pthread.h
.Ft int
.Fn pthread_key_delete "pthread_key_t key"
.Sh DESCRIPTION
The
.Fn pthread_key_delete
function deletes a thread-specific data key previously returned by
.Fn pthread_key_create .
The thread-specific data values associated with
.Fa key
need not be NULL at the time that
.Fn pthread_key_delete
is called.
It is the responsibility of the application to free any
application storage or perform any cleanup actions for data structures
related to the deleted key or associated thread-specific data in any threads;
this cleanup can be done either before or after
.Fn pthread_key_delete
is called.
Any attempt to use
.Fa key
following the call to
.Fn pthread_key_delete
results in undefined behavior.
.Pp
The
.Fn pthread_key_delete
function is callable from within destructor functions.
Destructor functions
are not invoked by
.Fn pthread_key_delete .
Any destructor function that may have been associated with
.Fa key
will no longer be called upon thread exit.
.Sh RETURN VALUES
If successful, the
.Fn pthread_key_delete
function will return zero.
Otherwise an error number will be returned to
indicate the error.
.Sh ERRORS
.Fn pthread_key_delete
may fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa key
value is invalid.
.El
.Sh SEE ALSO
.Xr pthread_getspecific 3 ,
.Xr pthread_key_create 3 ,
.Xr pthread_setspecific 3
.Sh STANDARDS
.Fn pthread_key_delete
conforms to
.St -p1003.1-96 .
.Sh BUGS
The current specifications of
.Fn pthread_key_create
and
.Fn pthread_key_delete
are flawed and do not permit a clean implementation without
potential problems.  The current implementation of these functions
.Nx
in addresses these problems by not supporting key reuse.