EventLoop.iteration: run timeouts last

Run timeouts last, in order to minimize latency in termination of
iteration loops that they may control.

diff --git a/pym/portage/util/_eventloop/EventLoop.py b/pym/portage/util/_eventloop/EventLoop.py
index 808c83d4cc7d0c2b543bcc5964a2691fbadb12db..475a4a9c6365749554cba1db5975d76433dfc8a0 100644 (file)
--- a/pym/portage/util/_eventloop/EventLoop.py
+++ b/pym/portage/util/_eventloop/EventLoop.py
@@ -130,10 +130,12 @@ class EventLoop(object):
                                                pass
                                        if self._run_timeouts():
                                                events_handled += 1
-                                       if not event_handlers:
-                                               return bool(events_handled)
-                               else:
-                                       return bool(events_handled)
+
+                       # If any timeouts have executed, then return immediately,
+                       # in order to minimize latency in termination of iteration
+                       # loops that they may control.
+                       if events_handled or not event_handlers:
+                               return bool(events_handled)
 
                if not event_queue:
 
@@ -149,17 +151,10 @@ class EventLoop(object):
                        else:
                                timeout = 0
 
-                       if self._run_timeouts():
-                               events_handled += 1
-
                        try:
-
                                self._poll(timeout=timeout)
                        except StopIteration:
-                               # This could happen if there are no IO event handlers
-                               # after _poll() calls _run_timeouts(), due to them
-                               # being removed by timeout or idle callbacks. It can
-                               # also be triggered by EINTR which is caused by signals.
+                               # This can be triggered by EINTR which is caused by signals.
                                pass
 
                # NOTE: IO event handlers may be re-entrant, in case something
@@ -172,6 +167,11 @@ class EventLoop(object):
                        if not x.callback(f, event, *x.args):
                                self.source_remove(x.source_id)
 
+               # Run timeouts last, in order to minimize latency in
+               # termination of iteration loops that they may control.
+               if self._run_timeouts():
+                       events_handled += 1
+
                return bool(events_handled)
 
        def child_watch_add(self, pid, callback, data=None):