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  initialization  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  XLockDisplay.   This  function  has  no  effect  unless  Xlib  was
       successfully initialized 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