This MR aims to fix a wrong behaviour that was observed a few times, when cancelling a snapshot export.

We now rely on the Lwt_exit clean-up callback mechanism to ensure clean-ups.

We now remove potential temporary directories left from an interrupted snapshot export.

Additionally, it removes the lock file when cancelling a snapshot import.

Manually testing the MR

Try to export a snapshot and cancel it (Ctrl-c) during the export. It might reproduce the behaviour at some point without the fix

for i in `seq 1 20`; do ./tezos-node snapshot export --data-dir ./snap --block head --rolling & ; sleep 2 ; kill -15 $!; done

For the import, cancel the import and look for the lock file in the data dir.

Checklist

Document the interface of any function added or modified (see the coding guidelines)
Document any change to the user interface, including configuration parameters (see node configuration)
Provide automatic testing (see the testing guide).
For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
Select suitable reviewers using the Reviewers field below.
Select as Assignee the next person who should take action on that MR

Edited Oct 26, 2022 by Victor Allombert