fix: egress id race condition

[kylezs]

Pull Request

Closes: PRO-689

Checklist

Please conduct a thorough self-review before opening the PR.

• I am confident that the code works.
• I have updated documentation where appropriate.

Summary

See the issue. This fixes it, by unifying the deposit_addresses adapter and the egress_items adapter under the hood. But still provides a wrapper for ease of use for each of these.

[codecov]

Codecov Report

Attention: 282 lines in your changes are missing coverage. Please review.

Comparison is base (f6a06c1) 71% compared to head (8df66b7) 71%.
Report is 4 commits behind head on main.

Files	Patch %	Lines
...d_chain_source/chunked_by_vault/monitored_items.rs	0%	192 Missing ⚠️
...nked_chain_source/chunked_by_vault/egress_items.rs	0%	43 Missing ⚠️
...chain_source/chunked_by_vault/deposit_addresses.rs	0%	34 Missing ⚠️
engine/src/witness/dot.rs	0%	10 Missing ⚠️
engine/src/witness/btc.rs	86%	3 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff           @@
##            main   #4235    +/-   ##
======================================
- Coverage     71%     71%    -0%     
======================================
  Files        384     385     +1     
  Lines      63007   63151   +144     
  Branches   63007   63151   +144     
======================================
+ Hits       45050   45071    +21     
- Misses     15617   15741   +124     
+ Partials    2340    2339     -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[linear]

PRO-689 Egress Id race condition

It's possible we're not witnessing a particular egress id / TransactionOutId at the time we receive the block that contains the egress transaction we should be watching for.

Copy of the TODO in the code:

// NB: There is a race condition here. If we're not watching for a particular egress id (because our state chain is slow for some reason) at the time
// it arrives on external chain, we won't witness it. This is pretty unlikely since the time between the egress id being set on the SC and the tx
// being confirmed on the external chain is quite large. We should fix this eventually though.

DOT and BTC egress witnessing need to know the set of transactions they are looking for, and therefore it is possible for the witnessers to be ahead (even with lag safety), and miss the block the transaction is included in, because it hasn't seen the SC block that contains the BroadcastRequest event that contains the details required to witness it.

Solution

The solution is to attach a chain tracking block number to the broadcast before the threshold signing request. This is because after a threshold signing is done, it's possible to broadcast the transaction.

We can then "hold up" Ethereum (for example) blocks until we know that we can't possibly have received an address to watch for before that Ethereum block.

First PR, the SC side: #4046

The second part of this is to effectively implement the deposit_addresses adapter for egress ids… and factor out the common code in the process.