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Date: Thu, 02 Apr 2015 13:19:22 -0400
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Subject: Re: [Qemu-devel] [Qemu-block] [PATCH v4 18/20] iotests: add QMP
 event waiting queue
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: famz@redhat.com, qemu-block@nongnu.org, qemu-devel@nongnu.org, armbru@redhat.com, vsementsov@parallels.com, stefanha@redhat.com, mreitz@redhat.com



On 04/02/2015 09:57 AM, Stefan Hajnoczi wrote:
> On Fri, Mar 20, 2015 at 03:17:01PM -0400, John Snow wrote:
>> +# Test if 'match' is a recursive subset of 'event'
>> +def event_match(event, match = None):
>
> Not worth respinning but PEP8 says there should be no spaces around the
> '=' for keyword arguments:
> https://www.python.org/dev/peps/pep-0008/#whitespace-in-expressions-and-statements
>
>> +    def event_wait(self, name='BLOCK_JOB_COMPLETED', maxtries=3, match=None):
>> +        # Search cached events
>> +        for event in self._events:
>> +            if (event['event'] == name) and event_match(event, match):
>> +                self._events.remove(event)
>> +                return event
>> +
>> +        # Poll for new events
>> +        for _ in range(maxtries):
>> +            event = self._qmp.pull_event(wait=True)
>> +            if (event['event'] == name) and event_match(event, match):
>> +                return event
>> +            self._events.append(event)
>> +
>> +        return None
>
> I'm not sure if maxtries is useful.  Why is a particular number of
> skipped events useful to the caller and how do they pick the magic
> number?
>
> If you added the argument because this is a blocking operation then we
> should probably use timeouts instead.  Timeouts will bail out even if
> QEMU is unresponsive.
>

Yeah, this was just a poor man's timeout.

I'll make it nicer.