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.\" Copyright \(co 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1994, 1996 X Consortium
.\"
.\" Permission is hereby granted, free of charge, to any person obtaining
.\" a copy of this software and associated documentation files (the
.\" "Software"), to deal in the Software without restriction, including
.\" without limitation the rights to use, copy, modify, merge, publish,
.\" distribute, sublicense, and/or sell copies of the Software, and to
.\" permit persons to whom the Software is furnished to do so, subject to
.\" the following conditions:
.\"
.\" The above copyright notice and this permission notice shall be included
.\" in all copies or substantial portions of the Software.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
.\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
.\" IN NO EVENT SHALL THE X CONSORTIUM BE LIABLE FOR ANY CLAIM, DAMAGES OR
.\" OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
.\" ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
.\" OTHER DEALINGS IN THE SOFTWARE.
.\"
.\" Except as contained in this notice, the name of the X Consortium shall
.\" not be used in advertising or otherwise to promote the sale, use or
.\" other dealings in this Software without prior written authorization
.\" from the X Consortium.
.\"
.\" Copyright \(co 1985, 1986, 1987, 1988, 1989, 1990, 1991 by
.\" Digital Equipment Corporation
.\"
.\" Portions Copyright \(co 1990, 1991 by
.\" Tektronix, Inc.
.\"
.\" Permission to use, copy, modify and distribute this documentation for
.\" any purpose and without fee is hereby granted, provided that the above
.\" copyright notice appears in all copies and that both that copyright notice
.\" and this permission notice appear in all copies, and that the names of
.\" Digital and Tektronix not be used in in advertising or publicity pertaining
.\" to this documentation without specific, written prior permission.
.\" Digital and Tektronix makes no representations about the suitability
.\" of this documentation for any purpose.
.\" It is provided "as is" without express or implied warranty.
.\"
.\"
.ds xT X Toolkit Intrinsics \- C Language Interface
.ds xW Athena X Widgets \- C Language X Toolkit Interface
.ds xL Xlib \- C Language X Interface
.ds xC Inter-Client Communication Conventions Manual
.TH XInitThreads __libmansuffix__ __xorgversion__ "XLIB FUNCTIONS"
.SH NAME
XInitThreads, XLockDisplay, XUnlockDisplay \- multi-threading support
.SH SYNTAX
.HP
Status XInitThreads\^(void);
.HP
Status XFreeThreads\^(void);
.HP
void XLockDisplay\^(\^Display *\fIdisplay\fP\^);
.HP
void XUnlockDisplay\^(\^Display *\fIdisplay\fP\^);
.SH ARGUMENTS
.IP \fIdisplay\fP 1i
Specifies the connection to the X server.
.SH DESCRIPTION
The
.B XInitThreads
function initializes Xlib support for concurrent threads.
This function must be the first Xlib function a
multi-threaded program calls, and it must complete
before any other Xlib call is made.
This function returns a nonzero status if initialization was
successful; otherwise, it returns zero.
On systems that do not support threads, this function always returns zero.
.LP
It is only necessary to call this function if multiple threads
might use Xlib concurrently.
If all calls to Xlib functions
are protected by some other access mechanism (for example,
a mutual exclusion lock in a toolkit or through explicit client
programming), Xlib thread initialization is not required.
It is recommended that single-threaded programs not call this function.
.LP
The
.B XFreeThreads
function frees the memory allocated by
.BR XInitThreads .
.LP
The
.B XLockDisplay
function locks out all other threads from using the specified display.
Other threads attempting to use the display will block until
the display is unlocked by this thread.
Nested calls to
.B XLockDisplay
work correctly; the display will not actually be unlocked until
.B XUnlockDisplay
has been called the same number of times as
.BR XLockDisplay .
This function has no effect unless Xlib was successfully initialized
for threads using
.BR XInitThreads .
.LP
The
.B XUnlockDisplay
function allows other threads to use the specified display again.
Any threads that have blocked on the display are allowed to continue.
Nested locking works correctly; if
.B XLockDisplay
has been called multiple times by a thread, then
.B XUnlockDisplay
must be called an equal number of times before the display is
actually unlocked.
This function has no effect unless Xlib was successfully initialized
for threads using
.BR XInitThreads .
.SH "SEE ALSO"
\fI\*(xL\fP
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