scripts: twister: Process KeyboardInterrupt Hardening

[LukaszMrugala]

If you interrupt process() operation, we want Twister to exit as gracefully as it can. This avoids the UnboundLocalError that could appear e.g. when interrupting the operation via SIGINT.

Currently, we can experience a situation like this:

INFO    - Adding tasks to the queue...
INFO    - Added initial list of jobs to queue
^CERROR   - General exception: cannot access local variable 'next_op' where it is not associated with a value
ERROR   - General exception: cannot access local variable 'next_op' where it is not associated with a value
ERROR   - General exception: cannot access local variable 'next_op' where it is not associated with a value
ERROR   - General exception: cannot access local variable 'next_op' where it is not associated with a value
ERROR   - General exception: cannot access local variable 'next_op' where it is not associated with a value
ERROR   - General exception: cannot access local variable 'next_op' where it is not associated with a value
ERROR   - General exception: cannot access local variable 'next_op' where it is not associated with a value
ERROR   - General exception: cannot access local variable 'next_op' where it is not associated with a value
ERROR   - General exception: cannot access local variable 'next_op' where it is not associated with a value
ERROR   - General exception: cannot access local variable 'next_op' where it is not associated with a value
ERROR   - General exception: cannot access local variable 'next_op' where it is not associated with a value
ERROR   - General exception: cannot access local variable 'next_op' where it is not associated with a value
INFO    - Execution interrupted

[golowanow]

Although I can't always reproduce the issue with Ctrl-C at precise moment, it seems reasonable to set these initial values, but I'm not sure yet is it enough to address the problem and exit gracefully. For example, I've also got errors like this:

^CINFO    - Execution interrupted
...
ERROR   - some_test: Unknown status 'None'

[LukaszMrugala]

^CINFO    - Execution interrupted
...
ERROR   - some_test: Unknown status 'None'

This would be caused by the interrupt making the instance get incorrect status and then proceeding to the report. Were you able to find what code section, when interrupted, results in that? It seems to be breaking the assumption of using TwisterStatus as status, so I'm interested in the mechanism of failure there.

At the same time, I'd point out that normally, I do not expect much from a CLI programme that I interrupt via Ctrl-C, save for it quitting.

[nashif]

^CINFO - Execution interrupted
...
ERROR - some_test: Unknown status 'None'

that is the original behavior and it is correct when you interrupt execution. Lets just fix this new bug and deal with improvement, if needed, later.

[LukaszMrugala]

^CINFO - Execution interrupted
...
ERROR - some_test: Unknown status 'None'

that is the original behavior and it is correct when you interrupt execution. Lets just fix this new bug and deal with improvement, if needed, later.

I have taken a look at it and it is slightly incorrect. It should report "No status", not "Unknown status", as per code. We ideally should never have a status that is not a TwisterStatus inside Twister. This is caused by dict.get('status') not being parametrised correctly here. A quick search reveal that it occurs semi-frequently in the code and I will create a separate PR to fix that.

[golowanow]

.. Lets just fix this new bug and deal with improvement, if needed, later.

I agree that better to fix this noisy bug, but I still suspect there might be other side effects from the recent design decision #77080 to put per-operation StatusAttributeError handlers with intent to continue execution there.