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tttk_block_while(3)


CDE


NAME

  tttk_block_while - block while a counter is greater than zero


SYNOPSIS

  #include <tttk.h>
  Tt_status tttk_block_while(XtAppContext app2run,
			     const int *blocked,
			     int ms_timeout);


DESCRIPTION

  The tttk_block_while function is used to process asynchronous events, such
  as ToolTalk messages or window system events, while waiting for a condition
  or timeout.

  If app2run is not zero, then an event loop is run for that application
  context, by repeatedly calling XtAppProcessEvent(3X) with ms_timeout being
  effected using XtAppAddTimeOut(3X). If app2run is zero, then the file
  descriptor (as returned by tt_fd(3)) of the default procid is polled (using
  the poll(2) function) and tttk_Xt_input_handler(3) is called whenever the
  file descriptor is active.

  If blocked is zero, then tttk_block_while runs until ms_timeout occurs. If
  blocked is non-zero, then the loop is run until either ms_timeout occurs,
  or *blocked is less than 1.

  If ms_timeout is zero, tttk_block_while checks once for events, processes
  the first one, and then returns.  If ms_timeout is negative, no timeout is
  in effect.


RETURN VALUE

  Upon successful completion, the tttk_block_while function returns the
  status of the operation as one of the following Tt_status values:

  TT_OK
      The operation completed successfully.

  TT_DESKTOP_ETIMEDOUT
      The timeout occurred within ms_timeout milliseconds, or ms_timeout was
      zero and no input was available.

  TT_DESKTOP_EINTR
      The app2run argument was zero, and poll(2) was interrupted by a signal.

  TT_DESKTOP_EAGAIN
      The app2run argument was zero, and poll(2) returned EAGAIN.

  If app2run is not zero and ms_timeout is negative, then tttk_block_while
  will only return when *blocked is less than 1, with TT_OK being returned.

  If app2run is not zero, ms_timeout is negative, and blocked is zero, then
  tttk_block_while behaves equivalent to XtAppMainLoop(3X), and will never
  return.


APPLICATION USAGE

  If app2run is zero, then only messaging events for the default procid will
  be serviced. Events for other procids will be blocked, as will window
  system events, so that the graphical user interface of the application will
  not update itself even, for example, after expose events.

  On the other hand, if the application passes its Xt context in as app2run,
  then window system events will continue to be handled, as will message
  activity for all procids for which an XtAppAddInput(3X) has been done.
  Since the window system event loop is fully operational in this case, the
  application should take care to disable any user interface controls that
  the user should not operate while the application is waiting for
  tttk_block_while to return.


SEE ALSO

  Tttttk(5), tttk_Xt_input_handler(3); poll(2), XtAppPending(3X),
  XtAppAddTimeOut(3X), XtAppNextEvent(3X), XtDispatchEvent(3X). poll in the
  X/Open CAE Specification, X/Open System Interfaces and Headers, Issue 4,
  Version 2; XtAppPending, XtAppAddTimeOut, XtAppNextEvent, XtDispatchEvent
  in the X/Open CAE Specification, X/Open Window Management: X Toolkit
  Intrinsics

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