refactor: builder uses stream and requires WS (#135)

Author: prestwich

bin/builder.rs

@@ -21,9 +21,14 @@ async fn main() -> eyre::Result<()> {
     let config = BuilderConfig::from_env()?.clone();
     let constants = SignetSystemConstants::pecorino();
 
+    // We connect the WS greedily, so we can fail early if the connection is
+    // invalid.
+    let ru_provider = config.connect_ru_provider().await?;
+
     // Spawn the EnvTask
     let env_task = config.env_task();
-    let (block_env, env_jh) = env_task.spawn();
+    let (block_env, env_jh) =
+        env_task.await.expect("ws validity checked in connect_ru_provider above").spawn();
 
     // Spawn the cache system
     let cache_tasks = CacheTasks::new(config.clone(), block_env.clone());
@@ -32,7 +37,6 @@ async fn main() -> eyre::Result<()> {
     // Prep providers and contracts
     let (host_provider, quincey) =
         tokio::try_join!(config.connect_host_provider(), config.connect_quincey())?;
-    let ru_provider = config.connect_ru_provider();
     let zenith = config.connect_zenith(host_provider.clone());
 
     // Set up the metrics task

src/config.rs

@@ -12,6 +12,7 @@ use alloy::{
             SimpleNonceManager, WalletFiller,
         },
     },
+    rpc::client::BuiltInConnectionString,
 };
 use eyre::Result;
 use init4_bin_base::{
@@ -63,11 +64,19 @@ pub struct BuilderConfig {
     pub ru_chain_id: u64,
 
     /// URL for Host RPC node.
-    #[from_env(var = "HOST_RPC_URL", desc = "URL for Host RPC node", infallible)]
+    #[from_env(
+        var = "HOST_RPC_URL",
+        desc = "URL for Host RPC node. This MUST be a valid HTTP or WS URL, starting with http://, https://, ws:// or wss://",
+        infallible
+    )]
     pub host_rpc_url: Cow<'static, str>,
 
     /// URL for the Rollup RPC node.
-    #[from_env(var = "ROLLUP_RPC_URL", desc = "URL for Rollup RPC node", infallible)]
+    #[from_env(
+        var = "ROLLUP_RPC_URL",
+        desc = "URL for Rollup RPC node. This MUST be a valid WS url starting with ws:// or wss://. Http providers are not supported.",
+        infallible
+    )]
     pub ru_rpc_url: Cow<'static, str>,
 
     /// URL of the tx pool to poll for incoming transactions.
@@ -176,14 +185,25 @@ impl BuilderConfig {
     }
 
     /// Connect to the Rollup rpc provider.
-    pub fn connect_ru_provider(&self) -> RootProvider<Ethereum> {
-        static ONCE: std::sync::OnceLock<RootProvider<Ethereum>> = std::sync::OnceLock::new();
+    pub async fn connect_ru_provider(&self) -> eyre::Result<RootProvider<Ethereum>> {
+        static ONCE: tokio::sync::OnceCell<RootProvider<Ethereum>> =
+            tokio::sync::OnceCell::const_new();
 
-        ONCE.get_or_init(|| {
-            let url = url::Url::parse(&self.ru_rpc_url).expect("failed to parse URL");
-            RootProvider::new_http(url)
+        ONCE.get_or_try_init(|| async {
+            let url = url::Url::parse(&self.ru_rpc_url)?;
+
+            let scheme = url.scheme();
+            eyre::ensure!(
+                scheme == "ws" || scheme == "wss",
+                "Invalid Rollup RPC URL scheme: {scheme}. Expected ws:// or wss://"
+            );
+
+            RootProvider::connect_with(BuiltInConnectionString::Ws(url, None))
+                .await
+                .map_err(Into::into)
         })
-        .clone()
+        .await
+        .cloned()
     }
 
     /// Connect to the Host rpc provider.
@@ -245,9 +265,9 @@ impl BuilderConfig {
     }
 
     /// Create an [`EnvTask`] using this config.
-    pub fn env_task(&self) -> EnvTask {
-        let ru_provider = self.connect_ru_provider();
-        EnvTask::new(self.clone(), ru_provider)
+    pub async fn env_task(&self) -> eyre::Result<EnvTask> {
+        let ru_provider = self.connect_ru_provider().await?;
+        Ok(EnvTask::new(self.clone(), ru_provider))
     }
 
     /// Create a [`SignetCfgEnv`] using this config.

src/tasks/env.rs

@@ -6,7 +6,6 @@ use alloy::{
     providers::Provider,
 };
 use init4_bin_base::deps::tracing::{self, Instrument, debug, error, info_span};
-use std::time::Duration;
 use tokio::{sync::watch, task::JoinHandle};
 use tokio_stream::StreamExt;
 use trevm::revm::{context::BlockEnv, context_interface::block::BlobExcessGasAndPrice};
@@ -58,39 +57,32 @@ impl EnvTask {
     /// Returns a sender that sends [`SimEnv`] for communicating the next block environment.
     async fn task_fut(self, sender: watch::Sender<Option<SimEnv>>) {
         let span = info_span!("EnvTask::task_fut::init");
-        let mut poller = match self.ru_provider.watch_blocks().instrument(span.clone()).await {
+
+        let mut blocks = match self.ru_provider.subscribe_blocks().await {
             Ok(poller) => poller,
             Err(err) => {
                 let _span = span.enter();
-                error!(%err, "Failed to watch blocks");
+                error!(%err, "Failed to subscribe to blocks");
                 return;
             }
-        };
-
-        poller.set_poll_interval(Duration::from_millis(250));
-
-        let mut blocks = poller.into_stream();
+        }
+        .into_stream();
 
-        while let Some(blocks) =
+        while let Some(block) =
             blocks.next().instrument(info_span!("EnvTask::task_fut::stream")).await
         {
-            let Some(block_hash) = blocks.last() else {
-                // This case occurs when there are no changes to the block,
-                // so we do nothing.
-                continue;
-            };
             let span =
-                info_span!("EnvTask::task_fut::loop", %block_hash, number = tracing::field::Empty);
+                info_span!("EnvTask::task_fut::loop", %block.hash, number = tracing::field::Empty);
 
             // Get the rollup header for rollup block simulation environment configuration
             let rollup_header = match self
-                .get_latest_rollup_header(&sender, block_hash, &span)
+                .get_latest_rollup_header(&sender, &block.hash, &span)
                 .await
             {
                 Some(value) => value,
                 None => {
                     // If we failed to get the rollup header, we skip this iteration.
-                    debug!(%block_hash, "failed to get rollup header - continuing to next block");
+                    debug!(%block.hash, "failed to get rollup header - continuing to next block");
                     continue;
                 }
             };

tests/block_builder_test.rs

@@ -42,7 +42,7 @@ async fn test_handle_build() {
     // Create a rollup provider
     let ru_provider = RootProvider::<Ethereum>::new_http(anvil_instance.endpoint_url());
 
-    let block_env = config.env_task().spawn().0;
+    let block_env = config.env_task().await.unwrap().spawn().0;
 
     let block_builder = Simulator::new(&config, ru_provider.clone(), block_env);
 

tests/cache.rs

@@ -12,7 +12,7 @@ async fn test_bundle_poller_roundtrip() -> eyre::Result<()> {
 
     let config = setup_test_config().unwrap();
 
-    let (block_env, _jh) = config.env_task().spawn();
+    let (block_env, _jh) = config.env_task().await.unwrap().spawn();
     let cache_tasks = CacheTasks::new(config.clone(), block_env);
     let cache_system = cache_tasks.spawn();
 

tests/env.rs

@@ -7,7 +7,7 @@ async fn test_bundle_poller_roundtrip() {
 
     let config = setup_test_config().unwrap();
     let env_task = config.env_task();
-    let (mut env_watcher, _jh) = env_task.spawn();
+    let (mut env_watcher, _jh) = env_task.await.unwrap().spawn();
 
     env_watcher.changed().await.unwrap();
     let env = env_watcher.borrow_and_update();