[libvirt] [PATCH] adding handling EINTR to poll to make it more robust

[Dan Kenigsberg]

On Thu, Jul 19, 2012 at 09:49:41AM +0800, Royce Lv wrote:
> some system call and signal will interrupt poll,
> making event loop stops and fails to react events and keepalive message
> from libvirt.
> adding handling EINTR to poll to make it more robust
> 
> Signed-off-by: Royce Lv <lvroyce at linux.vnet.ibm.com>
> ---
>  examples/domain-events/events-python/event-test.py |   87 +++++++++++---------
>  1 file changed, 46 insertions(+), 41 deletions(-)
> 
> diff --git a/examples/domain-events/events-python/event-test.py b/examples/domain-events/events-python/event-test.py
> index 96dc268..6b655cd 100644
> --- a/examples/domain-events/events-python/event-test.py
> +++ b/examples/domain-events/events-python/event-test.py
> @@ -178,48 +178,53 @@ class virEventLoopPure:
>      def run_once(self):
>          sleep = -1
>          self.runningPoll = True
> -        next = self.next_timeout()
> -        debug("Next timeout due at %d" % next)
> -        if next > 0:
> -            now = int(time.time() * 1000)
> -            if now >= next:
> -                sleep = 0
> -            else:
> -                sleep = (next - now) / 1000.0
> -
> -        debug("Poll with a sleep of %d" % sleep)
> -        events = self.poll.poll(sleep)
> -
> -        # Dispatch any file handle events that occurred
> -        for (fd, revents) in events:
> -            # See if the events was from the self-pipe
> -            # telling us to wakup. if so, then discard
> -            # the data just continue
> -            if fd == self.pipetrick[0]:
> -                self.pendingWakeup = False
> -                data = os.read(fd, 1)
> -                continue
> -
> -            h = self.get_handle_by_fd(fd)
> -            if h:
> -                debug("Dispatch fd %d handle %d events %d" % (fd, h.get_id(), revents))
> -                h.dispatch(self.events_from_poll(revents))
> -
> -        now = int(time.time() * 1000)
> -        for t in self.timers:
> -            interval = t.get_interval()
> -            if interval < 0:
> -                continue
> +        try:
> +            next = self.next_timeout()
> +            debug("Next timeout due at %d" % next)
> +            if next > 0:
> +                now = int(time.time() * 1000)
> +                if now >= next:
> +                    sleep = 0
> +                else:
> +                    sleep = (next - now) / 1000.0
> +
> +            debug("Poll with a sleep of %d" % sleep)
> +            events = self.poll.poll(sleep)
> +
> +            # Dispatch any file handle events that occurred
> +            for (fd, revents) in events:
> +                # See if the events was from the self-pipe
> +                # telling us to wakup. if so, then discard
> +                # the data just continue
> +                if fd == self.pipetrick[0]:
> +                    self.pendingWakeup = False
> +                    data = os.read(fd, 1)
> +                    continue
> +
> +                h = self.get_handle_by_fd(fd)
> +                if h:
> +                    debug("Dispatch fd %d handle %d events %d" % (fd, h.get_id(), revents))
> +                    h.dispatch(self.events_from_poll(revents))
>  
> -            want = t.get_last_fired() + interval
> -            # Deduct 20ms, since schedular timeslice
> -            # means we could be ever so slightly early
> -            if now >= (want-20):
> -                debug("Dispatch timer %d now %s want %s" % (t.get_id(), str(now), str(want)))
> -                t.set_last_fired(now)
> -                t.dispatch()
> -
> -        self.runningPoll = False
> +            now = int(time.time() * 1000)
> +            for t in self.timers:
> +                interval = t.get_interval()
> +                if interval < 0:
> +                    continue
> +
> +                want = t.get_last_fired() + interval
> +                # Deduct 20ms, since scheduler timeslice
> +                # means we could be ever so slightly early
> +                if now >= (want-20):
> +                    debug("Dispatch timer %d now %s want %s" % (t.get_id(), str(now), str(want)))
> +                    t.set_last_fired(now)
> +                    t.dispatch()
> +
> +        except (os.error, select.error), e:
> +            if e.args[0] != errno.EINTR:
> +                raise
> +        finally:
> +            self.runningPoll = False

Thanks, I'm happy with this version.