Do all timer stuff before blocking, avoiding a bunch of duplicate code
and merge common code in WaitForSomething.
The WaitForSomething changes need a bit of explanation to show that
the new code is effectively equivalent to the old. Eliding error
checking and trivial bits we've got:
Before:
if (ready clients)
timeout = 0
else
compute timeout
i = poll
if (i <= 0) {
if (ready clients)
return TRUE;
if (input)
return FALSE;
if (any ready timers) {
run timers
return FALSE;
}
} else {
if (input)
return FALSE;
if (any ready timers) {
run timers
return FALSE;
}
if (ready clients)
return TRUE;
}
After:
if (ready clients)
timeout = 0;
else
compute timeout
run_timers
poll
if (input)
return FALSE;
if (ready clients)
return TRUE;
The old code would return TRUE if there were ready clients and input
pending. Dispatch would then schedule that ready client, but before
processing any requests, it would notice that there was input pending
and go process it. The new code just checks for input first, which is
effectively the same.
If the poll timed out and there weren't clients ready, then timers
would get run.
If the poll didn't time out, then timers would get run, even if there
were clients now ready. Now, if the timeout interval was zero, that
means that the timers must have been ready *before* poll was
invoked. In this case, we should simply run the timers before calling
poll -- no sense calling poll just to discard any data that it
generates.
If the timeout interval was non-zero, and poll didn't timeout, then
either there aren't any timers to run, or we got a surprise and hit a
timer exactly as a client became ready to run. This is the one case
where the new code is different from the old; the new code delays the
timer call until the next time WaitForSomething is called.
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
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