ADR: Domain Decomposition

[brapse]

Domain Decomposition

[to address #326]

The objective here is to outline the dependency graph for the relayer that will facilitate

• Reasonable error handling and failure cases
• Testability
• Correct by construction data types
  • Only produce verified data so downstream data consumers don't have to deal with proof

Still a work in progress, probably needs to be scoped down. But the ideas are ready for critique ☺️

rendered

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For contributor use:

• Unit tests written
• Added test to CI if applicable
• Updated CHANGELOG_PENDING.md
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Updated relevant documentation (docs/) and code comments
• Re-reviewed Files changed in the Github PR explorer

[ebuchman]

Should these really be traits? IBC objects like Connection, Channel, Packet are all concrete types that don't vary across chains. Clients are more of an interface and do vary depending on the chain, so we end up with concrete types like the Tendermint Client, Grandpa Client, Local Client, etc.

[romac]

Agreed, if those don't vary across chain then they should definitely be plain structs, and we leave it to the traits to abstract over operations, etc. rather than data.

[codecov-io]

Codecov Report

Merging #162 into master will increase coverage by 21.4%.
The diff coverage is 63.2%.

@@            Coverage Diff            @@
##           master    #162      +/-   ##
=========================================
+ Coverage    13.6%   35.1%   +21.4%     
=========================================
  Files          69     137      +68     
  Lines        3752    8576    +4824     
  Branches     1374    2961    +1587     
=========================================
+ Hits          513    3012    +2499     
- Misses       2618    5374    +2756     
+ Partials      621     190     -431     

Impacted Files	Coverage Δ
modules/src/events.rs	0.0% <0.0%> (ø)
modules/src/ics02_client/events.rs	0.0% <ø> (ø)
modules/src/ics02_client/raw.rs	0.0% <0.0%> (ø)
modules/src/ics03_connection/error.rs	13.6% <0.0%> (-19.7%)	⬇️
modules/src/ics04_channel/error.rs	75.0% <ø> (+50.0%)	⬆️
modules/src/ics04_channel/packet.rs	0.0% <0.0%> (ø)
modules/src/ics07_tendermint/client_def.rs	0.0% <0.0%> (ø)
modules/src/ics07_tendermint/error.rs	75.0% <ø> (+75.0%)	⬆️
modules/src/ics18_relayer/error.rs	0.0% <0.0%> (ø)
modules/src/ics26_routing/msgs.rs	0.0% <0.0%> (ø)
... and 254 more

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[brapse]

This is implemented, can we go ahead and merge this @ancazamfir?

[ancazamfir]

Looks good at this point. I think we should update this along with the implementation.