feat(engine): allow configuring tree to always use state root fallback (#16569)

crates/engine/primitives/src/config.rs

@@ -77,6 +77,8 @@ pub struct TreeConfig {
     reserved_cpu_cores: usize,
     /// Whether to enable the precompile cache
     precompile_cache_enabled: bool,
+    /// Whether to use state root fallback for testing
+    state_root_fallback: bool,
 }
 
 impl Default for TreeConfig {
@@ -96,6 +98,7 @@ impl Default for TreeConfig {
             max_proof_task_concurrency: DEFAULT_MAX_PROOF_TASK_CONCURRENCY,
             reserved_cpu_cores: DEFAULT_RESERVED_CPU_CORES,
             precompile_cache_enabled: false,
+            state_root_fallback: false,
         }
     }
 }
@@ -118,6 +121,7 @@ impl TreeConfig {
         max_proof_task_concurrency: u64,
         reserved_cpu_cores: usize,
         precompile_cache_enabled: bool,
+        state_root_fallback: bool,
     ) -> Self {
         Self {
             persistence_threshold,
@@ -134,6 +138,7 @@ impl TreeConfig {
             max_proof_task_concurrency,
             reserved_cpu_cores,
             precompile_cache_enabled,
+            state_root_fallback,
         }
     }
 
@@ -204,6 +209,11 @@ impl TreeConfig {
         self.precompile_cache_enabled
     }
 
+    /// Returns whether to use state root fallback.
+    pub const fn state_root_fallback(&self) -> bool {
+        self.state_root_fallback
+    }
+
     /// Setter for persistence threshold.
     pub const fn with_persistence_threshold(mut self, persistence_threshold: u64) -> Self {
         self.persistence_threshold = persistence_threshold;
@@ -307,6 +317,12 @@ impl TreeConfig {
         self
     }
 
+    /// Setter for whether to use state root fallback, useful for testing.
+    pub const fn with_state_root_fallback(mut self, state_root_fallback: bool) -> Self {
+        self.state_root_fallback = state_root_fallback;
+        self
+    }
+
     /// Whether or not to use state root task
     pub const fn use_state_root_task(&self) -> bool {
         self.has_enough_parallelism && !self.legacy_state_root

crates/engine/tree/src/tree/mod.rs

@@ -2077,7 +2077,9 @@ where
         //
         // See https://github.com/paradigmxyz/reth/issues/12688 for more details
         let persisting_kind = self.persisting_kind_for(block.header());
-        let run_parallel_state_root = persisting_kind.can_run_parallel_state_root();
+        // don't run parallel if state root fallback is set
+        let run_parallel_state_root =
+            persisting_kind.can_run_parallel_state_root() && !self.config.state_root_fallback();
 
         // use prewarming background task
         let header = block.clone_sealed_header();
@@ -2215,8 +2217,13 @@ where
             maybe_state_root
         } else {
             // fallback is to compute the state root regularly in sync
-            warn!(target: "engine::tree", block=?block_num_hash, ?persisting_kind, "Failed to compute state root in parallel");
-            self.metrics.block_validation.state_root_parallel_fallback_total.increment(1);
+            if self.config.state_root_fallback() {
+                debug!(target: "engine::tree", block=?block_num_hash, "Using state root fallback for testing");
+            } else {
+                warn!(target: "engine::tree", block=?block_num_hash, ?persisting_kind, "Failed to compute state root in parallel");
+                self.metrics.block_validation.state_root_parallel_fallback_total.increment(1);
+            }
+
             let (root, updates) =
                 ensure_ok!(state_provider.state_root_with_updates(hashed_state.clone()));
             (root, updates, root_time.elapsed())

crates/node/core/src/args/engine.rs

@@ -63,6 +63,10 @@ pub struct EngineArgs {
     /// Enable precompile cache
     #[arg(long = "engine.precompile-cache", default_value = "false")]
     pub precompile_cache_enabled: bool,
+
+    /// Enable state root fallback, useful for testing
+    #[arg(long = "engine.state-root-fallback", default_value = "false")]
+    pub state_root_fallback: bool,
 }
 
 impl Default for EngineArgs {
@@ -80,6 +84,7 @@ impl Default for EngineArgs {
             max_proof_task_concurrency: DEFAULT_MAX_PROOF_TASK_CONCURRENCY,
             reserved_cpu_cores: DEFAULT_RESERVED_CPU_CORES,
             precompile_cache_enabled: false,
+            state_root_fallback: false,
         }
     }
 }
@@ -98,6 +103,7 @@ impl EngineArgs {
             .with_max_proof_task_concurrency(self.max_proof_task_concurrency)
             .with_reserved_cpu_cores(self.reserved_cpu_cores)
             .with_precompile_cache_enabled(self.precompile_cache_enabled)
+            .with_state_root_fallback(self.state_root_fallback)
     }
 }