The packet and its payloads are sent in separate events

[srdtrk]

Summary

Reconstructing a packet from a relayer's perspective is unnecessarily complex due to the need to process multiple events, which complicates event handling and increases the likelihood of errors.

Problem Definition

ibc-go/modules/core/04-channel/v2/keeper/events.go

Lines 14 to 53 in 8bae734

	func emitSendPacketEvents(ctx context.Context, packet types.Packet) {
	sdkCtx := sdk.UnwrapSDKContext(ctx)
	sdkCtx.EventManager().EmitEvents(sdk.Events{
	sdk.NewEvent(
	types.EventTypeSendPacket,
	sdk.NewAttribute(types.AttributeKeySrcChannel, packet.SourceChannel),
	sdk.NewAttribute(types.AttributeKeyDstChannel, packet.DestinationChannel),
	sdk.NewAttribute(types.AttributeKeySequence, fmt.Sprintf("%d", packet.Sequence)),
	sdk.NewAttribute(types.AttributeKeyTimeoutTimestamp, fmt.Sprintf("%d", packet.TimeoutTimestamp)),
	sdk.NewAttribute(types.AttributeKeyPayloadLength, fmt.Sprintf("%d", len(packet.Payloads))),
	sdk.NewAttribute(types.AttributeKeyVersion, packet.Payloads[0].Version),
	sdk.NewAttribute(types.AttributeKeyEncoding, packet.Payloads[0].Encoding),
	sdk.NewAttribute(types.AttributeKeyData, hex.EncodeToString(packet.Payloads[0].Value)),
	),
	sdk.NewEvent(
	sdk.EventTypeMessage,
	sdk.NewAttribute(sdk.AttributeKeyModule, types.AttributeValueCategory),
	),
	})
	for i, payload := range packet.Payloads {
	sdkCtx.EventManager().EmitEvents(sdk.Events{
	sdk.NewEvent(
	types.EventTypeSendPayload,
	sdk.NewAttribute(types.AttributeKeySrcChannel, packet.SourceChannel),
	sdk.NewAttribute(types.AttributeKeyDstChannel, packet.DestinationChannel),
	sdk.NewAttribute(types.AttributeKeySequence, fmt.Sprintf("%d", packet.Sequence)),
	sdk.NewAttribute(types.AttributeKeyPayloadSequence, fmt.Sprintf("%d", i)),
	sdk.NewAttribute(types.AttributeKeyVersion, payload.Version),
	sdk.NewAttribute(types.AttributeKeyEncoding, payload.Encoding),
	sdk.NewAttribute(types.AttributeKeyData, hex.EncodeToString(payload.Value)),
	),
	sdk.NewEvent(
	sdk.EventTypeMessage,
	sdk.NewAttribute(sdk.AttributeKeyModule, types.AttributeValueCategory),
	),
	})
	}
	}

Since event support has not yet fully arrived (#7386), the same problem would also occur for write acknowledgement events once they are implemented.

Use cases

Improved Developer Experience

• Relayer developers can work with a more intuitive event model, reducing development and debugging time.

Cleaner Codebase in IBC-Go

• Consolidating packet data into a single event simplifies code logic, reducing maintenance overhead and potential for bugs.

Enhanced Ecosystem Interoperability

• A more streamlined event structure aligns with modern approaches, like Solidity-IBC-Eureka, fostering consistency across implementations.

Proposal

We can simply include the all payload information in the same event or do what solidity-ibc-eureka is doing and encode the entire packet as a single key-value pair.

We may also want to modify the spec so that all packet info is contained in a single event.

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For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged/assigned
• Estimate provided