Re: [PATCH 05/10] python/machine: Disable pylint warning for open() in _pre_launch

[John Snow <jsnow@redhat.com>]

On 5/14/21 10:42 AM, Wainer dos Santos Moschetta wrote:
> Hi,
> 
> On 5/12/21 6:46 PM, John Snow wrote:
>> Shift the open() call later so that the pylint pragma applies *only* to
>> that one open() call. Add a note that suggests why this is safe: the
>> resource is unconditionally cleaned up in _post_shutdown().
> 
> 
> You can also put it in a pylint disable/enable block. E.g.:
> 
>      # pylint: disable=consider-using-with
> 
>      self._qemu_log_file = open(self._qemu_log_path, 'wb')
> 
>      # pylint: enable=consider-using-with
> 
> However I don't know if this is bad practice. :)
> 

I learned a new trick!

> Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
> 

Thanks. In this case I will probably leave this alone unless someone 
else voices a strong opinion. I figure the comment protects us against 
future oopses well enough.

>>
>> _post_shutdown is called after failed launches (see launch()), and
>> unconditionally after every call to shutdown(), and therefore also on
>> __exit__.
>>
>> Signed-off-by: John Snow <jsnow@redhat.com>
>> ---
>>   python/qemu/machine.py | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/python/qemu/machine.py b/python/qemu/machine.py
>> index c13ff9b32bf..8f86303b48f 100644
>> --- a/python/qemu/machine.py
>> +++ b/python/qemu/machine.py
>> @@ -308,7 +308,6 @@ def _pre_launch(self) -> None:
>>           self._temp_dir = tempfile.mkdtemp(prefix="qemu-machine-",
>>                                             dir=self._test_dir)
>>           self._qemu_log_path = os.path.join(self._temp_dir, 
>> self._name + ".log")
>> -        self._qemu_log_file = open(self._qemu_log_path, 'wb')
>>           if self._console_set:
>>               self._remove_files.append(self._console_address)
>> @@ -323,6 +322,11 @@ def _pre_launch(self) -> None:
>>                   nickname=self._name
>>               )
>> +        # NOTE: Make sure any opened resources are *definitely* freed in
>> +        # _post_shutdown()!
>> +        # pylint: disable=consider-using-with
>> +        self._qemu_log_file = open(self._qemu_log_path, 'wb')
>> +
>>       def _post_launch(self) -> None:
>>           if self._qmp_connection:
>>               self._qmp.accept()