Call forkchoiceUpdated

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -3037,6 +3037,14 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             .start_slot(T::EthSpec::slots_per_epoch());
         let head_proposer_index = new_head.beacon_block.message().proposer_index();
 
+        // Used later for the execution engine.
+        let new_head_execution_block_hash = new_head
+            .beacon_block
+            .message()
+            .body()
+            .execution_payload()
+            .map(|ep| ep.block_hash);
+
         drop(lag_timer);
 
         // Update the snapshot that stores the head of the chain at the time it received the
@@ -3174,9 +3182,67 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             }
         }
 
+        // If this is a post-merge block, update the execution layer.
+        if let Some(new_head_execution_block_hash) = new_head_execution_block_hash {
+            let execution_layer = self
+                .execution_layer
+                .clone()
+                .ok_or(Error::ExecutionLayerMissing)?;
+            let store = self.store.clone();
+            let log = self.log.clone();
+
+            // Spawn the update task, without waiting for it to complete.
+            execution_layer.spawn(
+                move |execution_layer| async move {
+                    if let Err(e) = Self::update_execution_engine_forkchoice(
+                        execution_layer,
+                        store,
+                        new_finalized_checkpoint.root,
+                        new_head_execution_block_hash,
+                    )
+                    .await
+                    {
+                        error!(
+                            log,
+                            "Failed to update execution head";
+                            "error" => ?e
+                        );
+                    }
+                },
+                "update_execution_engine_forkchoice",
+            )
+        }
+
         Ok(())
     }
 
+    pub async fn update_execution_engine_forkchoice(
+        execution_layer: ExecutionLayer,
+        store: BeaconStore<T>,
+        finalized_beacon_block_root: Hash256,
+        head_execution_block_hash: Hash256,
+    ) -> Result<(), Error> {
+        // Loading the finalized block from the store is not ideal. Perhaps it would be better to
+        // store it on fork-choice so we can do a lookup without hitting the database.
+        //
+        // See: https://github.com/sigp/lighthouse/pull/2627#issuecomment-927537245
+        let finalized_block = store
+            .get_block(&finalized_beacon_block_root)?
+            .ok_or(Error::MissingBeaconBlock(finalized_beacon_block_root))?;
+
+        let finalized_execution_block_hash = finalized_block
+            .message()
+            .body()
+            .execution_payload()
+            .map(|ep| ep.block_hash)
+            .unwrap_or_else(Hash256::zero);
+
+        execution_layer
+            .forkchoice_updated(head_execution_block_hash, finalized_execution_block_hash)
+            .await
+            .map_err(Error::ExecutionForkChoiceUpdateFailed)
+    }
+
     /// This function takes a configured weak subjectivity `Checkpoint` and the latest finalized `Checkpoint`.
     /// If the weak subjectivity checkpoint and finalized checkpoint share the same epoch, we compare
     /// roots. If we the weak subjectivity checkpoint is from an older epoch, we iterate back through

beacon_node/beacon_chain/src/errors.rs

@@ -134,6 +134,8 @@ pub enum BeaconChainError {
         new_slot: Slot,
     },
     AltairForkDisabled,
+    ExecutionLayerMissing,
+    ExecutionForkChoiceUpdateFailed(execution_layer::Error),
 }
 
 easy_from_to!(SlotProcessingError, BeaconChainError);

beacon_node/execution_layer/src/lib.rs

@@ -74,23 +74,36 @@ impl ExecutionLayer {
         &self.inner.engines
     }
 
+    fn executor(&self) -> &TaskExecutor {
+        &self.inner.executor
+    }
+
     fn log(&self) -> &Logger {
         &self.inner.log
     }
 
     /// Convenience function to allow calling async functions in a non-async context.
-    pub fn block_on<'a, T, U, V>(&'a self, future: T) -> Result<V, Error>
+    pub fn block_on<'a, T, U, V>(&'a self, generate_future: T) -> Result<V, Error>
     where
         T: Fn(&'a Self) -> U,
         U: Future<Output = Result<V, Error>>,
     {
         let runtime = self
-            .inner
+            .executor()
-            .executor
             .runtime()
             .upgrade()
             .ok_or(Error::ShuttingDown)?;
-        runtime.block_on(future(self))
+        // TODO(paul): respect the shutdown signal.
+        runtime.block_on(generate_future(self))
+    }
+
+    /// Convenience function to allow calling spawning a task without waiting for the result.
+    pub fn spawn<T, U>(&self, generate_future: T, name: &'static str)
+    where
+        T: FnOnce(Self) -> U,
+        U: Future<Output = ()> + Send + 'static,
+    {
+        self.executor().spawn(generate_future(self.clone()), name);
     }
 
     pub async fn prepare_payload(
@@ -179,4 +192,30 @@ impl ExecutionLayer {
             ))
         }
     }
+
+    pub async fn forkchoice_updated(
+        &self,
+        head_block_hash: Hash256,
+        finalized_block_hash: Hash256,
+    ) -> Result<(), Error> {
+        let broadcast_results = self
+            .engines()
+            .broadcast(|engine| {
+                engine
+                    .api
+                    .forkchoice_updated(head_block_hash, finalized_block_hash)
+            })
+            .await;
+
+        if broadcast_results.iter().any(Result::is_ok) {
+            Ok(())
+        } else {
+            Err(Error::EngineErrors(
+                broadcast_results
+                    .into_iter()
+                    .filter_map(Result::err)
+                    .collect(),
+            ))
+        }
+    }
 }