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

[John Snow]

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()