XInitThreads(3)

NAME

       XInitThreads, XLockDisplay, XUnlockDisplay - multi-threading support

SYNTAX

       Status XInitThreads(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 initial-
       ization is not required.  It is recommended that single-threaded pro-
       grams not call this function.

       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 1.1.1                  XInitThreads(3)