Respect request drops properly in spawned execution tasks

[mattsse]

Describe the feature

currently all rpc calls follow this pattern:

reth/crates/rpc/rpc-eth-api/src/helpers/call.rs

Lines 207 to 220 in 8f5b4ae

	/// Executes the call request (`eth_call`) and returns the output
	fn call(
	&self,
	request: RpcTxReq<<Self::RpcConvert as RpcConvert>::Network>,
	block_number: Option<BlockId>,
	overrides: EvmOverrides,
	) -> impl Future<Output = Result<Bytes, Self::Error>> + Send {
	async move {
	let res =
	self.transact_call_at(request, block_number.unwrap_or_default(), overrides).await?;
	Self::Error::ensure_success(res.result)
	}
	}

reth/crates/rpc/rpc-eth-api/src/helpers/call.rs

Lines 538 to 541 in 8f5b4ae

	let this = self.clone();
	self.spawn_with_call_at(request, at, overrides, move |db, evm_env, tx_env| {
	this.transact(db, evm_env, tx_env)
	})

this gets called from the rpc request's context but the spawned task that performs the execution is fully detached and usually fully sync (evm execution)

we can use a tokio_util::sync::CancellationToken; and check during sync execution if this was cancelled and on the callsite use the drop_guard()

TODO

• introduce a struct CallCtx {token: Cancellationtoken} that for now just wraps the token (we use a struct in case we need more things later)
• Integrate in spawn fns: like

  reth/crates/rpc/rpc-eth-api/src/helpers/call.rs

  Lines 579 to 585 in 8f5b4ae

  	fn spawn_with_call_at<F, R>(
  	&self,
  	request: RpcTxReq<<Self::RpcConvert as RpcConvert>::Network>,
  	at: BlockId,
  	overrides: EvmOverrides,
  	f: F,
  	) -> impl Future<Output = Result<R, Self::Error>> + Send

• Instantiate it and the drop guard on the callsite

  reth/crates/rpc/rpc-eth-api/src/helpers/call.rs

  Lines 539 to 541 in 8f5b4ae

  	self.spawn_with_call_at(request, at, overrides, move |db, evm_env, tx_env| {
  	this.transact(db, evm_env, tx_env)
  	})

we can start with eth_call and then also integrate this in heaver tracing calls

Additional context

No response

[woojinnn]

Can I?

[mattsse]

@woojinnn thank you, still thinking how to do this properly, so I'm gonna mark this as in house for now, will have more task shortly