MountLock context manager (was: Exception handling in mount/unmount; Enable lint check W0706)

[feman323]

W0706 complains if an Exception is directly raised back without any handling. First I wanted to remove the try / catch blocks completely, but the I've seen that there are also "finally" statements. Therefore I just added some logging, which caused the lint check to run successful.

[buhtz]

Hi Manual,
thank your for this contribution. I would set this as draft because it needs further investigation and resources.
Your solution might silence the linter but does not improve the quality of code or BIT behavior. The log output is polluted without any reason.

There is more wrong then just a not handled exception. On a quick view I would assume that the goal of this code construct was that the code block in finally will be executed no matter if there is an exception or not. It might have been the only way in older Python versions but not in today Python.

Today you would solve something like this with a context manager.

But I am not sure at all and would need some time to dive into it.

Best,
Christian

As an example you see here that the exception is re-raised but finally is also executed.

>>> try:
...   x = 7 / 0
... except Exception:
...    raise
... finally:
...   print('FF')
... 
FF
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
ZeroDivisionError: division by zero
>>> 

[feman323]

Hi Christian,

Okay, I will try to embed this in a context manager.

Regards,

Manuel

[buhtz]

Please have a look if our (quit fresh) flock module and its base class _FlockContext might help you. I am assuming that base class need to be modified somehow to be more flexible.

[buhtz]

My advice would be to extract the five methods mountLock*() and mountProcess*() into something else. A context manager class for example.