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Re: [libvirt] [PATCH] add handling EINTR to test example of event loop



On Mon, Jun 18, 2012 at 10:56:26AM +0100, Daniel P. Berrange wrote:
> On Mon, Jun 18, 2012 at 05:43:55PM +0800, lvroyce linux vnet ibm com wrote:
> > From: lvroyce <lvroyce linux vnet ibm com>
> > 
> > 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: lvroyce <lvroyce linux vnet ibm com>
> > ---
> >  examples/domain-events/events-python/event-test.py |    8 +++++++-
> >  1 files changed, 7 insertions(+), 1 deletions(-)
> > 
> > diff --git a/examples/domain-events/events-python/event-test.py b/examples/domain-events/events-python/event-test.py
> > index 96dc268..b446c21 100644
> > --- a/examples/domain-events/events-python/event-test.py
> > +++ b/examples/domain-events/events-python/event-test.py
> > @@ -188,7 +188,13 @@ class virEventLoopPure:
> >                  sleep = (next - now) / 1000.0
> >  
> >          debug("Poll with a sleep of %d" % sleep)
> > -        events = self.poll.poll(sleep)
> > +        try:
> > +            events = self.poll.poll(sleep)
> > +        except select.error, e:
> > +                self.runningPoll = False
> > +                if not e.errno in (errno.EINTR, errno.EAGAIN):
> > +                    raise
> > +                return
> 
> It isn't possible for poll() to return EAGAIN according to the
> manpage.
> 
> If you remove that errno, then the patch would be ok. Also the
> indentation in the except: block is too deep - line it up with
> the try: block

The same function has another possible exception-raiser: os.read() few
lines below, and probably others. How about putting

        self.runningPoll = False

in a "finally" clause opened right after the first self.runningPoll
assignment?

Dan


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