Optimizing IBC Transaction Searches: Implementing a Unique Event Attribute for Enhanced Relayer Performance

[beer-1]

Summary

Adding a new event attribute for packet send, receive, acknowledgment, and timeout events can address performance issues in relayers.

Problem Definition

As described here, there are many cases where we need to search the IBC transaction body.

CometBFT's current txSearch implementation attempts to load all transactions that match each condition and then find their intersection. This approach causes millions of transactions to be loaded into memory, forcing CometBFT to iterate through these millions of transactions to find the intersection.

Use cases

Currently, all stateless IBC Relayers use transaction or block searches to retrieve the transaction body from the event in order to clear stalled packets.

Proposal

We propose introducing a new event attribute as follows:

sdk.NewAttribute(types.AttributeKeyId, sha3.Sum256(
	append([]byte(packet.GetSourcePort()), 
	append([]byte(packet.GetSourceChannel()), 
	append([]byte(packet.GetDestPort()), 
	append([]byte(packet.GetDestChannel(), 
	[]byte(fmt.Sprintf("%d", packet.GetSequence()))...)...)...)...))),

Then we can search IBC tx body with unique tx search key.

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[AdityaSripal]

Hi thanks for the issue writeup!

I'm a bit confused as to the need for this. Events make sense to use for new packets being created. However, if you want to clear packets there are RPC query endpoints that exist for this purpose that would be much more efficient. Is there a reason Hermes doesn't use these?