XInitThreads(3) XLIB FUNCTIONS XInitThreads(3)
NAME
XInitThreads, XLockDisplay, XUnlockDisplay - multi-threading support
SYNTAX
Status XInitThreads(void);
Status XFreeThreads(void);
void XLockDisplay(Display *display);
void XUnlockDisplay(Display *display);
ARGUMENTS
display Specifies the connection to the X server.
DESCRIPTION
The 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.
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 initializa-
tion is not required. It is recommended that single-threaded programs
not call this function.
The XFreeThreads function frees the memory allocated by XInitThreads.
The 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
XLockDisplay work correctly; the display will not actually be unlocked
until XUnlockDisplay has been called the same number of times as XLock-
Display. This function has no effect unless Xlib was successfully ini-
tialized for threads using XInitThreads.
The 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 XLockDisplay has been
called multiple times by a thread, then 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 XInitThreads.
SEE ALSO
Xlib - C Language X Interface
X Version 11 libX11 1.8.12 XInitThreads(3)
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