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



On Mon, Jun 18, 2012 at 10:17:53PM +0300, Dan Kenigsberg wrote:
> 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?
 
Sounds like a reasonable idea.

Daniel
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