Send FCUs to L2/Builder concurrently (#206)

* Make FCU calls concurrent

* Fix

* Fix tests

* Remove debug statement

* More fixes

* Remove print statement

* Remove from README

* Update flag

* Fix lint

* chore: simplify concurrent fcu logic (#208)

* chore: simplify concurrent fcu logic

* fix: remove duplicate file

* chore: remove unused function

* docs: document when fcu does not contain payload attrs

* docs: fix comments

* docs: use l2 client instead of execution client

---------

Co-authored-by: 0xKitsune <[email protected]>

Author: ferranbt

.env.example

@@ -23,5 +23,4 @@ DEBUG_SERVER_PORT=5555
 TRACING=false
 LOG_LEVEL=info
 METRICS=false
-BOOST_SYNC=false
 LOG_FORMAT=text

README.md

@@ -24,7 +24,6 @@ cargo run -- [OPTIONS]
 - `--log-level <LEVEL>`: Log level (default: info)
 - `--log-format <FORMAT>`: Log format (default: text)
 - `--metrics`: Enable metrics (default: false)
-- `--no-boost-sync`: Disables using the proposer to sync the builder node (default: true)
 - `--debug-host <HOST>`: Host to run the server on (default: 127.0.0.1)
 - `--debug-server-port <PORT>`: Port to run the debug server on (default: 5555)
 
@@ -99,13 +98,6 @@ By default, `rollup-boost` will proxy all RPC calls from the proposer `op-node`
 - `miner_*`: this allows the builder to be aware of changes in effective gas price, extra data, and [DA throttling requests](https://docs.optimism.io/builders/chain-operators/configuration/batcher) from the batcher.
 - `eth_sendRawTransaction*`: this forwards transactions the proposer receives to the builder for block building. This call may not come from the proposer `op-node`, but directly from the rollup's rpc engine.
 
-### Boost Sync
-
-By default, `rollup-boost` will sync the builder with the proposer `op-node`. After the builder is synced, boost sync improves the performance of keeping the builder in sync with the tip of the chainby removing the need to receive chain updates via p2p via the builder `op-node`. This entails additional engine api calls that are multiplexed to the builder from rollup-boost:
-
-- `engine_forkchoiceUpdatedV3`: this call will be multiplexed to the builder regardless of whether the call contains payload attributes or not.
-- `engine_newPayloadV3`: ensures the builder has the latest block if the local payload was used.
-
 ## Debug API
 
 The Debug API is a JSON-RPC API that can be used to configure rollup-boost's execution mode. The execution mode determines how rollup-boost makes requests to the builder:

src/cli.rs

@@ -35,10 +35,6 @@ pub struct Args {
     #[arg(long, env, default_value = "5")]
     pub max_unsafe_interval: u64,
 
-    /// Disable using the proposer to sync the builder node
-    #[arg(long, env, default_value = "false")]
-    pub no_boost_sync: bool,
-
     /// Host to run the server on
     #[arg(long, env, default_value = "0.0.0.0")]
     pub rpc_host: String,
@@ -159,17 +155,11 @@ impl Args {
             PayloadSource::Builder,
         )?;
 
-        let boost_sync_enabled = !self.no_boost_sync;
-        if boost_sync_enabled {
-            info!("Boost sync enabled");
-        }
-
         let (probe_layer, probes) = ProbeLayer::new();
 
         let rollup_boost = RollupBoostServer::new(
             l2_client,
             builder_client,
-            boost_sync_enabled,
             self.execution_mode,
             probes,
             self.health_check_interval,