Support batched JSON-RPC requests in Lotus

[raulk]

Context

Batched requests are an optional feature in the JSON-RPC 2.0 specification. However, Ethereum clients offer this feature and downstream users like block explorers (e.g. Blockscout) depend on it.

In the past, the Lotus team rejected this feature and redirected users to using the WebSockets endpoint, on the grounds that it would have similar network properties. However, the desire to have Ethereum applications interact seamlessly with Lotus brings about an added motivation to build this feature.

Proposed plan

1. Implement batching in go-jsonrpc with sequential processing of individual requests.
2. If necessary, in the near future we can optimise by adding a worker pool for fork-join concurrency.

[alvin-reyes]

Hi @Stebalien, @raulk

I was trying to hook the wallaby testnet on to my local blockscout and its seems to fail due to the lack of support for batch json-rpc requests. I'd be interested to know when can we have this so I can deploy a blockscout instance for FEVM.

[maciejwitowski]

I'm considering assigning it to @geoff-vball for this week.
What do you think @geoff-vball @jennijuju @raulk?

[maciejwitowski]

Discussed on slack to deprioritise it for now.

[Stebalien]

This has already been merged.