flag to determine if calculating state root (#241)

* calculate state root

* fix tests

* add no state root test

* check no tx pool instead

* comments

* optimize

* fix lint

* use no tx pool

* add condition

Author: cody-wang-cb

crates/op-rbuilder/src/args/op.rs

@@ -147,6 +147,14 @@ pub struct FlashblocksArgs {
         env = "FLASHBLOCK_LEEWAY_TIME"
     )]
     pub flashblocks_leeway_time: u64,
+
+    /// Should we calculate state root for each flashblock
+    #[arg(
+        long = "flashblocks.calculate-state-root",
+        default_value = "true",
+        env = "FLASHBLOCKS_CALCULATE_STATE_ROOT"
+    )]
+    pub flashblocks_calculate_state_root: bool,
 }
 
 impl Default for FlashblocksArgs {

crates/op-rbuilder/src/builders/flashblocks/config.rs

@@ -28,6 +28,9 @@ pub struct FlashblocksConfig {
 
     /// Disables dynamic flashblocks number adjustment based on FCU arrival time
     pub fixed: bool,
+
+    /// Should we calculate state root for each flashblock
+    pub calculate_state_root: bool,
 }
 
 impl Default for FlashblocksConfig {
@@ -37,6 +40,7 @@ impl Default for FlashblocksConfig {
             interval: Duration::from_millis(250),
             leeway_time: Duration::from_millis(50),
             fixed: false,
+            calculate_state_root: true,
         }
     }
 }
@@ -56,11 +60,14 @@ impl TryFrom<OpRbuilderArgs> for FlashblocksConfig {
 
         let fixed = args.flashblocks.flashblocks_fixed;
 
+        let calculate_state_root = args.flashblocks.flashblocks_calculate_state_root;
+
         Ok(Self {
             ws_addr,
             interval,
             leeway_time,
             fixed,
+            calculate_state_root,
         })
     }
 }

crates/op-rbuilder/src/builders/flashblocks/payload.rs

@@ -37,6 +37,7 @@ use reth_provider::{
 use reth_revm::{
     State, database::StateProviderDatabase, db::states::bundle_state::BundleRetention,
 };
+use reth_trie::{HashedPostState, updates::TrieUpdates};
 use revm::Database;
 use rollup_boost::{
     ExecutionPayloadBaseV1, ExecutionPayloadFlashblockDeltaV1, FlashblocksPayloadV1,
@@ -222,6 +223,7 @@ where
 
         let chain_spec = self.client.chain_spec();
         let timestamp = config.attributes.timestamp();
+        let calculate_state_root = self.config.specific.calculate_state_root;
         let block_env_attributes = OpNextBlockEnvAttributes {
             timestamp,
             suggested_fee_recipient: config.attributes.suggested_fee_recipient(),
@@ -299,18 +301,25 @@ where
             ctx.add_builder_tx(&mut info, &mut state, builder_tx_gas, message.clone());
         }
 
-        let (payload, fb_payload) = build_block(&mut state, &ctx, &mut info)?;
+        let (payload, fb_payload) = build_block(
+            &mut state,
+            &ctx,
+            &mut info,
+            calculate_state_root || ctx.attributes().no_tx_pool, // need to calculate state root for CL sync
+        )?;
 
         best_payload.set(payload.clone());
         self.send_payload_to_engine(payload);
-
-        let flashblock_byte_size = self
-            .ws_pub
-            .publish(&fb_payload)
-            .map_err(PayloadBuilderError::other)?;
-        ctx.metrics
-            .flashblock_byte_size_histogram
-            .record(flashblock_byte_size as f64);
+        // not emitting flashblock if no_tx_pool in FCU, it's just syncing
+        if !ctx.attributes().no_tx_pool {
+            let flashblock_byte_size = self
+                .ws_pub
+                .publish(&fb_payload)
+                .map_err(PayloadBuilderError::other)?;
+            ctx.metrics
+                .flashblock_byte_size_histogram
+                .record(flashblock_byte_size as f64);
+        }
 
         info!(
             target: "payload_builder",
@@ -513,7 +522,8 @@ where
                     };
 
                     let total_block_built_duration = Instant::now();
-                    let build_result = build_block(&mut state, &ctx, &mut info);
+                    let build_result =
+                        build_block(&mut state, &ctx, &mut info, calculate_state_root);
                     let total_block_built_duration = total_block_built_duration.elapsed();
                     ctx.metrics
                         .total_block_built_duration
@@ -823,6 +833,7 @@ fn build_block<DB, P, ExtraCtx>(
     state: &mut State<DB>,
     ctx: &OpPayloadBuilderCtx<ExtraCtx>,
     info: &mut ExecutionInfo<ExtraExecutionInfo>,
+    calculate_state_root: bool,
 ) -> Result<(OpBuiltPayload, FlashblocksPayloadV1), PayloadBuilderError>
 where
     DB: Database<Error = ProviderError> + AsRef<P>,
@@ -867,28 +878,34 @@ where
     // TODO: maybe recreate state with bundle in here
     // // calculate the state root
     let state_root_start_time = Instant::now();
-    let state_provider = state.database.as_ref();
-    let hashed_state = state_provider.hashed_post_state(execution_outcome.state());
-    let (state_root, trie_output) = {
-        state
-            .database
-            .as_ref()
-            .state_root_with_updates(hashed_state.clone())
-            .inspect_err(|err| {
-                warn!(target: "payload_builder",
-                parent_header=%ctx.parent().hash(),
-                    %err,
-                    "failed to calculate state root for payload"
-                );
-            })?
-    };
-    let state_root_calculation_time = state_root_start_time.elapsed();
-    ctx.metrics
-        .state_root_calculation_duration
-        .record(state_root_calculation_time);
-    ctx.metrics
-        .state_root_calculation_gauge
-        .set(state_root_calculation_time);
+    let mut state_root = B256::ZERO;
+    let mut trie_output = TrieUpdates::default();
+    let mut hashed_state = HashedPostState::default();
+
+    if calculate_state_root {
+        let state_provider = state.database.as_ref();
+        hashed_state = state_provider.hashed_post_state(execution_outcome.state());
+        (state_root, trie_output) = {
+            state
+                .database
+                .as_ref()
+                .state_root_with_updates(hashed_state.clone())
+                .inspect_err(|err| {
+                    warn!(target: "payload_builder",
+                    parent_header=%ctx.parent().hash(),
+                        %err,
+                        "failed to calculate state root for payload"
+                    );
+                })?
+        };
+        let state_root_calculation_time = state_root_start_time.elapsed();
+        ctx.metrics
+            .state_root_calculation_duration
+            .record(state_root_calculation_time);
+        ctx.metrics
+            .state_root_calculation_gauge
+            .set(state_root_calculation_time);
+    }
 
     let mut requests_hash = None;
     let withdrawals_root = if ctx

crates/op-rbuilder/src/tests/flashblocks.rs

@@ -16,6 +16,7 @@ use crate::{
         flashblocks_block_time: 200,
         flashblocks_leeway_time: 100,
         flashblocks_fixed: false,
+        flashblocks_calculate_state_root: true,
     },
     ..Default::default()
 })]
@@ -53,6 +54,7 @@ async fn smoke_dynamic_base(rbuilder: LocalInstance) -> eyre::Result<()> {
         flashblocks_block_time: 200,
         flashblocks_leeway_time: 100,
         flashblocks_fixed: false,
+        flashblocks_calculate_state_root: true,
     },
     ..Default::default()
 })]
@@ -90,6 +92,7 @@ async fn smoke_dynamic_unichain(rbuilder: LocalInstance) -> eyre::Result<()> {
         flashblocks_block_time: 200,
         flashblocks_leeway_time: 50,
         flashblocks_fixed: true,
+        flashblocks_calculate_state_root: true,
     },
     ..Default::default()
 })]
@@ -127,6 +130,7 @@ async fn smoke_classic_unichain(rbuilder: LocalInstance) -> eyre::Result<()> {
         flashblocks_block_time: 200,
         flashblocks_leeway_time: 50,
         flashblocks_fixed: true,
+        flashblocks_calculate_state_root: true,
     },
     ..Default::default()
 })]
@@ -164,6 +168,7 @@ async fn smoke_classic_base(rbuilder: LocalInstance) -> eyre::Result<()> {
         flashblocks_block_time: 200,
         flashblocks_leeway_time: 100,
         flashblocks_fixed: false,
+        flashblocks_calculate_state_root: true,
     },
     ..Default::default()
 })]
@@ -203,6 +208,7 @@ async fn unichain_dynamic_with_lag(rbuilder: LocalInstance) -> eyre::Result<()>
         flashblocks_block_time: 200,
         flashblocks_leeway_time: 0,
         flashblocks_fixed: false,
+        flashblocks_calculate_state_root: true,
     },
     ..Default::default()
 })]
@@ -240,6 +246,7 @@ async fn dynamic_with_full_block_lag(rbuilder: LocalInstance) -> eyre::Result<()
         flashblocks_block_time: 200,
         flashblocks_leeway_time: 100,
         flashblocks_fixed: false,
+        flashblocks_calculate_state_root: true,
     },
     ..Default::default()
 })]
@@ -299,6 +306,7 @@ async fn test_flashblock_min_filtering(rbuilder: LocalInstance) -> eyre::Result<
         flashblocks_block_time: 200,
         flashblocks_leeway_time: 100,
         flashblocks_fixed: false,
+        flashblocks_calculate_state_root: true,
     },
     ..Default::default()
 })]
@@ -354,6 +362,7 @@ async fn test_flashblock_max_filtering(rbuilder: LocalInstance) -> eyre::Result<
         flashblocks_block_time: 200,
         flashblocks_leeway_time: 100,
         flashblocks_fixed: false,
+        flashblocks_calculate_state_root: true,
     },
     ..Default::default()
 })]
@@ -388,3 +397,47 @@ async fn test_flashblock_min_max_filtering(rbuilder: LocalInstance) -> eyre::Res
 
     flashblocks_listener.stop().await
 }
+
+#[rb_test(flashblocks, args = OpRbuilderArgs {
+    chain_block_time: 1000,
+    flashblocks: FlashblocksArgs {
+        enabled: true,
+        flashblocks_port: 1239,
+        flashblocks_addr: "127.0.0.1".into(),
+        flashblocks_block_time: 200,
+        flashblocks_leeway_time: 100,
+        flashblocks_fixed: false,
+        flashblocks_calculate_state_root: false,
+    },
+    ..Default::default()
+})]
+async fn test_flashblocks_no_state_root_calculation(rbuilder: LocalInstance) -> eyre::Result<()> {
+    use alloy_primitives::B256;
+
+    let driver = rbuilder.driver().await?;
+
+    // Send a transaction to ensure block has some activity
+    let _tx = driver
+        .create_transaction()
+        .random_valid_transfer()
+        .send()
+        .await?;
+
+    // Build a block with current timestamp (not historical) and calculate_state_root: false
+    let block = driver.build_new_block_with_current_timestamp(None).await?;
+
+    // Verify that flashblocks are still produced (block should have transactions)
+    assert!(
+        block.transactions.len() > 2,
+        "Block should contain transactions"
+    ); // deposit + builder tx + user tx
+
+    // Verify that state root is not calculated (should be zero)
+    assert_eq!(
+        block.header.state_root,
+        B256::ZERO,
+        "State root should be zero when calculate_state_root is false"
+    );
+
+    Ok(())
+}