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 initialization is not required.  It is recommended that  single-
       threaded programs 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 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