{suspend, resume} xcm execution when {enter, exit}ing maintenance-mode

[amarsinghcodes]

MOON-1483

Suspends xcm execution of messages in xcmp_queue::on_idle when entering maintenance-mode

Resumes xcm execution of messages in xcmp_queue::on_idle when exiting maintenance-mode

Removes the XcmpHandler associated types from pallet maintenance mode

Relevant:

• paritytech/cumulus@7749187
• xcm queue paused and resume AcalaNetwork/Acala#1737 (comment)

[girazoki]

Do we need the Handlers at all now?

[amarsinghcodes]

hmmm I think we do, the new code just stops executing XCM in xcmp_queue::on_idle. I don't think it changes how messages are otherwise handled...

[girazoki]

Let's remove the dmp & xcmp handlers from the config and verify all tests pass. I think thats the ultimate check that we need to ensure this behaves as we expect

[amarsinghcodes]

Let's remove the dmp & xcmp handlers from the config and verify all tests pass. I think thats the ultimate check that we need to ensure this behaves as we expect

Sounds good, I'll try it. I don't think they do the same thing though...

[amarsinghcodes]

@girazoki the CI says the TS test fails without the handlers:

  1) Pallet Maintenance Mode - dmp messages should queue in maintenance mode
       should queue xcm with maintenance mode and execute when off:

      AssertionError: expected false to equal true
      + expected - actual

      -false
      +true
      
      at Context.<anonymous> (tests/test-pallet-maintenance-mode.ts:509:38)
      at runMicrotasks (<anonymous>)
      at processTicksAndRejections (internal/process/task_queues.js:95:5)

So I will revert removing the handlers

[girazoki]

Oh I see whats going on here. I think initially the cumulus PR was set to pause the XCMP and DMP queues, but it finally made in with only the XCMP queue. So what we can remove is the XCMP handler, not the DMP one. I think the xcmp handler test works fine

[girazoki]

More generally, I think we might be able to do this for both queues with https://github.com/paritytech/polkadot/pull/5035/files But for now I think we can remove the XCMP queue. Can you mention this PR as a TODO in the DMP handler so that we dont forget to remove it in the future?