From 2b97779880d6aafc8a7787b637485eda0892364e Mon Sep 17 00:00:00 2001
From: Matthias Seitz <matthias.seitz@outlook.de>
Date: Thu, 10 Oct 2024 02:54:39 +0200
Subject: [PATCH] fix: persist finalized block (#11623)

---
 crates/engine/tree/src/persistence.rs | 17 ++++++++++++++++-
 crates/engine/tree/src/tree/mod.rs    |  9 ++++++++-
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/crates/engine/tree/src/persistence.rs b/crates/engine/tree/src/persistence.rs
index a748ece8a7..231945b336 100644
--- a/crates/engine/tree/src/persistence.rs
+++ b/crates/engine/tree/src/persistence.rs
@@ -4,7 +4,7 @@ use reth_chain_state::ExecutedBlock;
 use reth_errors::ProviderError;
 use reth_provider::{
     providers::ProviderNodeTypes, writer::UnifiedStorageWriter, BlockHashReader,
-    DatabaseProviderFactory, ProviderFactory, StaticFileProviderFactory,
+    DatabaseProviderFactory, FinalizedBlockWriter, ProviderFactory, StaticFileProviderFactory,
 };
 use reth_prune::{PrunerError, PrunerOutput, PrunerWithFactory};
 use reth_stages_api::{MetricEvent, MetricEventsSender};
@@ -92,6 +92,10 @@ impl<N: ProviderNodeTypes> PersistenceService<N> {
                     // we ignore the error because the caller may or may not care about the result
                     let _ = sender.send(res);
                 }
+                PersistenceAction::SaveFinalizedBlock(finalized_block) => self
+                    .provider
+                    .database_provider_rw()?
+                    .save_finalized_block_number(finalized_block)?,
             }
         }
         Ok(())
@@ -168,6 +172,9 @@ pub enum PersistenceAction {
     /// Prune associated block data before the given block number, according to already-configured
     /// prune modes.
     PruneBefore(u64, oneshot::Sender<PrunerOutput>),
+
+    /// Update the persisted finalized block on disk
+    SaveFinalizedBlock(u64),
 }
 
 /// A handle to the persistence service
@@ -235,6 +242,14 @@ impl PersistenceHandle {
         self.send_action(PersistenceAction::SaveBlocks(blocks, tx))
     }
 
+    /// Persists the finalized block number on disk.
+    pub fn save_finalized_block_number(
+        &self,
+        finalized_block: u64,
+    ) -> Result<(), SendError<PersistenceAction>> {
+        self.send_action(PersistenceAction::SaveFinalizedBlock(finalized_block))
+    }
+
     /// Tells the persistence service to remove blocks above a certain block number. The removed
     /// blocks are returned by the service.
     ///
diff --git a/crates/engine/tree/src/tree/mod.rs b/crates/engine/tree/src/tree/mod.rs
index 0478c73c90..5a39bc9901 100644
--- a/crates/engine/tree/src/tree/mod.rs
+++ b/crates/engine/tree/src/tree/mod.rs
@@ -2358,7 +2358,14 @@ where
                 return Err(OnForkChoiceUpdated::invalid_state())
             }
             Ok(Some(finalized)) => {
-                self.canonical_in_memory_state.set_finalized(finalized);
+                if Some(finalized.num_hash()) !=
+                    self.canonical_in_memory_state.get_finalized_num_hash()
+                {
+                    // we're also persisting the finalized block on disk so we can reload it on
+                    // restart this is required by optimism which queries the finalized block: <https://github.com/ethereum-optimism/optimism/blob/c383eb880f307caa3ca41010ec10f30f08396b2e/op-node/rollup/sync/start.go#L65-L65>
+                    let _ = self.persistence.save_finalized_block_number(finalized.number);
+                    self.canonical_in_memory_state.set_finalized(finalized);
+                }
             }
             Err(err) => {
                 error!(target: "engine::tree", %err, "Failed to fetch finalized block header");