Re: [PATCH v4 1/3] qmp.py: change event_wait to use a dict

[John Snow <jsnow@redhat.com>]

On 5/14/20 10:47 AM, Kevin Wolf wrote:
> Am 14.05.2020 um 04:25 hat John Snow geschrieben:
>> It's easier to work with than a list of tuples, because we can check the
>> keys for membership.
>>
>> Signed-off-by: John Snow <jsnow@redhat.com>
>> ---
>>  python/qemu/machine.py        | 10 +++++-----
>>  tests/qemu-iotests/040        | 12 ++++++------
>>  tests/qemu-iotests/260        |  5 +++--
>>  tests/qemu-iotests/iotests.py | 16 ++++++++--------
>>  4 files changed, 22 insertions(+), 21 deletions(-)
> 
> I think you need to convert scripts/simplebench/bench_block_job.py, too.

Oh, right -- that one is new since I did this. A lot of these scripts
need to be moved over into the python/ directory and managed under the
same pylint/mypy regime as everything else.

A *ton* of our scripts are in various states of disrepair.

> 
>> diff --git a/python/qemu/machine.py b/python/qemu/machine.py
>> index b9a98e2c86..eaedc25172 100644
>> --- a/python/qemu/machine.py
>> +++ b/python/qemu/machine.py
>> @@ -478,21 +478,21 @@ def event_wait(self, name, timeout=60.0, match=None):
>>          timeout: QEMUMonitorProtocol.pull_event timeout parameter.
>>          match: Optional match criteria. See event_match for details.
>>          """
>> -        return self.events_wait([(name, match)], timeout)
>> +        return self.events_wait({name: match}, timeout)
>>  
>>      def events_wait(self, events, timeout=60.0):
>>          """
>>          events_wait waits for and returns a named event from QMP with a timeout.
>>  
>> -        events: a sequence of (name, match_criteria) tuples.
>> +        events: a mapping containing {name: match_criteria}.
>>                  The match criteria are optional and may be None.
>>                  See event_match for details.  timeout:
>>                  QEMUMonitorProtocol.pull_event timeout parameter.
>>                  """
>>          def _match(event):
>> -            for name, match in events:
>> -                if event['event'] == name and self.event_match(event, match):
>> -                    return True
>> +            name = event['event']
>> +            if name in events:
>> +                return self.event_match(event, events[name])
> 
> This part confused me a bit for a second. Of course, that's probably
> mostly just me, but I feel 'events' isn't a good name any more when the
> values of the dict are match strings rather than events.
> 

This is honestly a really bad function. When I was trying to type
everything, this one was at the bottom of the pile and it was the worst.

It needs an overhaul.

In my 32 patch series, I left the "match" types as "Any" pretty much
everywhere, because it's such a laissez-faire series of functions.

I'll keep the feedback in mind.

>>              return False
>>  
>>          # Search cached events
>> diff --git a/tests/qemu-iotests/040 b/tests/qemu-iotests/040
>> index 32c82b4ec6..90b59081ff 100755
>> --- a/tests/qemu-iotests/040
>> +++ b/tests/qemu-iotests/040
>> @@ -485,12 +485,12 @@ class TestErrorHandling(iotests.QMPTestCase):
>>  
>>      def run_job(self, expected_events, error_pauses_job=False):
>>          match_device = {'data': {'device': 'job0'}}
>> -        events = [
>> -            ('BLOCK_JOB_COMPLETED', match_device),
>> -            ('BLOCK_JOB_CANCELLED', match_device),
>> -            ('BLOCK_JOB_ERROR', match_device),
>> -            ('BLOCK_JOB_READY', match_device),
>> -        ]
>> +        events = {
>> +            'BLOCK_JOB_COMPLETED': match_device,
>> +            'BLOCK_JOB_CANCELLED': match_device,
>> +            'BLOCK_JOB_ERROR': match_device,
>> +            'BLOCK_JOB_READY': match_device,
>> +        }
>>  
>>          completed = False
>>          log = []
>> diff --git a/tests/qemu-iotests/260 b/tests/qemu-iotests/260
>> index 804a7addb9..729f031122 100755
>> --- a/tests/qemu-iotests/260
>> +++ b/tests/qemu-iotests/260
>> @@ -67,8 +67,9 @@ def test(persistent, restart):
>>  
>>      vm.qmp_log('block-commit', device='drive0', top=top,
>>                 filters=[iotests.filter_qmp_testfiles])
>> -    ev = vm.events_wait((('BLOCK_JOB_READY', None),
>> -                         ('BLOCK_JOB_COMPLETED', None)))
>> +    ev = vm.events_wait({
>> +        'BLOCK_JOB_READY': None,
>> +        'BLOCK_JOB_COMPLETED': None })
> 
> So, I'm not sure if this is nitpicking or rather bikeshedding, but
> having the closing brackets on the next line would be more consistent
> with the other instances in this patch.
> 

Nah, it's fine. I'll clean it up. This is pretty close to an RFC series
anyway, so I didn't really polish it.

(Or, I will try to clean it up. I probably won't work on it again in the
near term. I think I just wanted to see if this seemed useful in general
to people.

As part of maybe moving the python library onto a package, I thought
that maybe developing a JobRunner tool would be useful to have in that
library. As you can see, I nestled it into iotests.py, though.)

>>      log(filter_qmp_event(ev))
>>      if (ev['event'] == 'BLOCK_JOB_COMPLETED'):
>>          vm.shutdown()
> 
> Kevin
> 

-- 
—js