Move more engine API impl logic into type EngineAPI

[mattsse]

Describe the feature

This type implements the engine API for both ethereum and OP

reth/crates/rpc/rpc-engine-api/src/engine_api.rs

Line 45 in c74d2a0

pub struct EngineApi<Provider, EngineT: EngineTypes, Pool, Validator, ChainSpec> {

via:

reth/crates/rpc/rpc-engine-api/src/engine_api.rs

Lines 635 to 636 in c74d2a0

	impl<Provider, EngineT, Pool, Validator, ChainSpec> EngineApiServer<EngineT>
	for EngineApi<Provider, EngineT, Pool, Validator, ChainSpec>

most of the logic is already directly implemented on EngineApi, but some logic is still part of the trait impl, e.g.:

reth/crates/rpc/rpc-engine-api/src/engine_api.rs

Lines 644 to 656 in c74d2a0

	/// Handler for `engine_newPayloadV1`
	/// See also <https://github.com/ethereum/execution-apis/blob/3d627c95a4d3510a8187dd02e0250ecb4331d27e/src/engine/paris.md#engine_newpayloadv1>
	/// Caution: This should not accept the `withdrawals` field
	async fn new_payload_v1(&self, payload: ExecutionPayloadV1) -> RpcResult<PayloadStatus> {
	trace!(target: "rpc::engine", "Serving engine_newPayloadV1");
	let start = Instant::now();
	let gas_used = payload.gas_used;
	let res = Self::new_payload_v1(self, payload).await;
	let elapsed = start.elapsed();
	self.inner.metrics.latency.new_payload_v1.record(elapsed);
	self.inner.metrics.new_payload_response.update_response_metrics(&res, gas_used, elapsed);
	Ok(res?)
	}

Eventually we want to use a different rpc server implementation for ethereum and OP but it would be nice if this only requires a trait impl and delegation.

for example:

impl EngineApiServer for EngineApi {
       async fn new_payload_v1(&self, payload: ExecutionPayloadV1) -> RpcResult<PayloadStatus> {
        trace!(target: "rpc::engine", "Serving engine_newPayloadV1");
        Ok(Self::new_payload_v1_metered(payload).await?)
      }
}

impl EngineApi {
   
    async fn new_payload_v1_metered(&self, payload: ExecutionPayloadV1) -> RpcResult<PayloadStatus> {
        let start = Instant::now();
        let res = Self::fork_choice_updated_v3(self, fork_choice_state, payload_attributes).await;
        self.inner.metrics.latency.fork_choice_updated_v3.record(start.elapsed());
        self.inner.metrics.fcu_response.update_response_metrics(&res);
    }
} 

effectively duplicating the function in impl EngineApi

most of this already exists, but we can move even more, like metric updates.

this should be done as 1 PR per function

Additional context

No response

[Parikalp-Bhardwaj]

Hi @mattsse, can I work on this issue

[Gerson2102]

I would like to do this mate @mattsse