Re: gdk_input_add

[Matias Freytes <mfreytes gtwing efn uncor edu>]

Hello,

> >     I'm using gdk_input_add to get notified about three
> > events. One of these events occurs as much as 20 times in a
> > second, but service time is often longer than 50ms. On the other
> > hand, the two other events occur less frequently.
> >
> > Do events accumulate on a pending list or similar?
> > Is there any way to make sure that I am not missing any of the
> > "low freq" events, and that they are handled in the correct
> > order?
>
> For gdk_input_add(), you shouldn't ever miss any events. i.e. your
> callback will always get called if there's data. However there are no
> real guarantees about order or granularity I don't believe.  poll() is
> the system call used to implement the main loop which just waits on
> multiple file descriptors. If when entering the poll() call more than
> one descriptor is already ready for reading, poll() will immediately
> return and input handlers for each descriptor will be called. You
> could have any amount of data on each descriptor and any number of
> descriptors ready for reading at that point.

Ok. So, just to make sure I got the idea, it's kind of:

fd_set set;
struct timeval t;
int n;

FD_ZERO(&set);
FD_SET(fd1, &set);
FD_SET(fd2, &set);
FD_SET(fd3, &set);
  ...
FD_SET(fdN, &set);

t.tv_sec = 0;
t.tv_usec = 0;


while (<loop condition>) {

   /*Assuming fdN is the highest descriptor */
   n = select(fdN+1, &set, NULL, NULL, &t);
   if (n>0) {
      if (FD_ISSET(fd1, &set)) {
         fd1_handler ();
      }

      if (FD_ISSET(fd2, &set)) {
         fd2_handler ();
      }

      if (FD_ISSET(fd3, &set)) {
         fd3_handler ();
      }

      .....

      if (FD_ISSET(fdN, &set)) {
         fd2_handler ();
      }
   } else {
      /* Either timeout or error */
   }
}


Is there any way I can force the order of the
"FD_ISSET (fdN, &set)" conditions?

Is this related to the order of the gdk_input_add() calls?

Should I care about XtAppPeekEvent(), XtAppPending(),
XtAppNextEvent(), XtDispatchEvent(&event), etc, or is this
handled in the main loop of GTK?

Thank you,
Matias.

PS: please cc.