Clear the mempool by using a sync method

[upbqdn]

Addresses #2773 (comment)

I changed

zebra/zebra-state/src/service/chain_tip.rs

Line 313 in 44ac067

pub async fn tip_change(&mut self) -> Result<TipAction, watch::error::RecvError> {

to a private method so that get_tip_change() doesn't miss any tip changes.

[teor2345]

This looks good, there are just a few tricky edge cases we need to handle.

[teor2345]

Seems like I gave some bad advice here - we can't use unconstrained until we upgrade tokio.

But the alternative refactor gives us simpler and faster code, so let's just do that.

[upbqdn]

All suggestions should be implemented now.

[jvff]

LGTM. I added a few optional suggestions, but they're minor.

[upbqdn]

Now I'm not sure whether to merge this into main or the parent branch.

[teor2345]

We could merge this as-is, but I'd like to fix a potential future performance issue.
(I expect we'll be using last_tip_change a lot, at the same time as the state is committing thousands of blocks.)

[teor2345]

Now I'm not sure whether to merge this into main or the parent branch.

We could:

• merge Clear the mempool by using a sync method #2777 into Clear mempool at a network upgrade #2773
• merge Clear mempool at a network upgrade #2773 into main
• rebase Cancel download and verify tasks when the mempool is deactivated #2764 on the new main

But I'm happy to let @conradoplg make the final call here, because #2764 is his PR.

[conradoplg]

But I'm happy to let @conradoplg make the final call here, because #2764 is his PR.

I agree with the plan 👍 I can merge this after that last required change

[upbqdn]

@conradoplg both PRs should be ready.