Indicate that invalid blocks are optimistic (#3383)

## Issue Addressed

NA

## Proposed Changes

This PR will make Lighthouse return blocks with invalid payloads via the API with `execution_optimistic = true`. This seems a bit awkward, however I think it's better than returning a 404 or some other error.

Let's consider the case where the only possible head is invalid (#3370 deals with this). In such a scenario all of the duties endpoints will start failing because the head is invalid. I think it would be better if the duties endpoints continue to work, because it's likely that even though the head is invalid the duties are still based upon valid blocks and we want the VC to have them cached. There's no risk to the VC here because we won't actually produce an attestation pointing to an invalid head.

Ultimately, I don't think it's particularly important for us to distinguish between optimistic and invalid blocks on the API. Neither should be trusted and the only *real* reason that we track this is so we can try and fork around the invalid blocks.


## Additional Info

- ~~Blocked on #3370~~

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -4131,8 +4131,9 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     /// Returns the value of `execution_optimistic` for `block`.
     ///
     /// Returns `Ok(false)` if the block is pre-Bellatrix, or has `ExecutionStatus::Valid`.
-    /// Returns `Ok(true)` if the block has `ExecutionStatus::Optimistic`.
-    pub fn is_optimistic_block<Payload: ExecPayload<T::EthSpec>>(
+    /// Returns `Ok(true)` if the block has `ExecutionStatus::Optimistic` or has
+    /// `ExecutionStatus::Invalid`.
+    pub fn is_optimistic_or_invalid_block<Payload: ExecPayload<T::EthSpec>>(
         &self,
         block: &SignedBeaconBlock<T::EthSpec, Payload>,
     ) -> Result<bool, BeaconChainError> {
@@ -4142,7 +4143,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         } else {
             self.canonical_head
                 .fork_choice_read_lock()
-                .is_optimistic_block(&block.canonical_root())
+                .is_optimistic_or_invalid_block(&block.canonical_root())
                 .map_err(BeaconChainError::ForkChoiceError)
         }
     }
@@ -4150,7 +4151,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     /// Returns the value of `execution_optimistic` for `head_block`.
     ///
     /// Returns `Ok(false)` if the block is pre-Bellatrix, or has `ExecutionStatus::Valid`.
-    /// Returns `Ok(true)` if the block has `ExecutionStatus::Optimistic`.
+    /// Returns `Ok(true)` if the block has `ExecutionStatus::Optimistic` or `ExecutionStatus::Invalid`.
     ///
     /// This function will return an error if `head_block` is not present in the fork choice store
     /// and so should only be used on the head block or when the block *should* be present in the
@@ -4158,7 +4159,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     ///
     /// There is a potential race condition when syncing where the block_root of `head_block` could
     /// be pruned from the fork choice store before being read.
-    pub fn is_optimistic_head_block<Payload: ExecPayload<T::EthSpec>>(
+    pub fn is_optimistic_or_invalid_head_block<Payload: ExecPayload<T::EthSpec>>(
         &self,
         head_block: &SignedBeaconBlock<T::EthSpec, Payload>,
     ) -> Result<bool, BeaconChainError> {
@@ -4168,7 +4169,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         } else {
             self.canonical_head
                 .fork_choice_read_lock()
-                .is_optimistic_block_no_fallback(&head_block.canonical_root())
+                .is_optimistic_or_invalid_block_no_fallback(&head_block.canonical_root())
                 .map_err(BeaconChainError::ForkChoiceError)
         }
     }
@@ -4177,17 +4178,17 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     /// You can optionally provide `head_info` if it was computed previously.
     ///
     /// Returns `Ok(false)` if the head block is pre-Bellatrix, or has `ExecutionStatus::Valid`.
-    /// Returns `Ok(true)` if the head block has `ExecutionStatus::Optimistic`.
+    /// Returns `Ok(true)` if the head block has `ExecutionStatus::Optimistic` or `ExecutionStatus::Invalid`.
     ///
     /// There is a potential race condition when syncing where the block root of `head_info` could
     /// be pruned from the fork choice store before being read.
-    pub fn is_optimistic_head(&self) -> Result<bool, BeaconChainError> {
+    pub fn is_optimistic_or_invalid_head(&self) -> Result<bool, BeaconChainError> {
         self.canonical_head
             .head_execution_status()
-            .map(|status| status.is_optimistic())
+            .map(|status| status.is_optimistic_or_invalid())
     }
 
-    pub fn is_optimistic_block_root(
+    pub fn is_optimistic_or_invalid_block_root(
         &self,
         block_slot: Slot,
         block_root: &Hash256,
@@ -4198,7 +4199,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         } else {
             self.canonical_head
                 .fork_choice_read_lock()
-                .is_optimistic_block_no_fallback(block_root)
+                .is_optimistic_or_invalid_block_no_fallback(block_root)
                 .map_err(BeaconChainError::ForkChoiceError)
         }
     }

beacon_node/beacon_chain/src/canonical_head.rs

@@ -752,7 +752,9 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     ) -> Result<(), Error> {
         let old_snapshot = &old_cached_head.snapshot;
         let new_snapshot = &new_cached_head.snapshot;
-        let new_head_is_optimistic = new_head_proto_block.execution_status.is_optimistic();
+        let new_head_is_optimistic = new_head_proto_block
+            .execution_status
+            .is_optimistic_or_invalid();
 
         // Detect and potentially report any re-orgs.
         let reorg_distance = detect_reorg(
@@ -883,7 +885,9 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         finalized_proto_block: ProtoBlock,
     ) -> Result<(), Error> {
         let new_snapshot = &new_cached_head.snapshot;
-        let finalized_block_is_optimistic = finalized_proto_block.execution_status.is_optimistic();
+        let finalized_block_is_optimistic = finalized_proto_block
+            .execution_status
+            .is_optimistic_or_invalid();
 
         self.op_pool
             .prune_all(&new_snapshot.beacon_state, self.epoch()?);
@@ -1260,7 +1264,7 @@ fn observe_head_block_delays<E: EthSpec, S: SlotClock>(
     let block_time_set_as_head = timestamp_now();
     let head_block_root = head_block.root;
     let head_block_slot = head_block.slot;
-    let head_block_is_optimistic = head_block.execution_status.is_optimistic();
+    let head_block_is_optimistic = head_block.execution_status.is_optimistic_or_invalid();
 
     // Calculate the total delay between the start of the slot and when it was set as head.
     let block_delay_total = get_slot_delay_ms(block_time_set_as_head, head_block_slot, slot_clock);

beacon_node/beacon_chain/tests/payload_invalidation.rs

@@ -291,7 +291,7 @@ impl InvalidPayloadRig {
                 let execution_status = self.execution_status(root.into());
 
                 match forkchoice_response {
-                    Payload::Syncing => assert!(execution_status.is_optimistic()),
+                    Payload::Syncing => assert!(execution_status.is_strictly_optimistic()),
                     Payload::Valid => assert!(execution_status.is_valid_and_post_bellatrix()),
                     Payload::Invalid { .. }
                     | Payload::InvalidBlockHash
@@ -421,7 +421,7 @@ async fn invalid_payload_invalidates_parent() {
     })
     .await;
 
-    assert!(rig.execution_status(roots[0]).is_optimistic());
+    assert!(rig.execution_status(roots[0]).is_strictly_optimistic());
     assert!(rig.execution_status(roots[1]).is_invalid());
     assert!(rig.execution_status(roots[2]).is_invalid());
 
@@ -555,7 +555,7 @@ async fn pre_finalized_latest_valid_hash() {
         if slot == 1 {
             assert!(rig.execution_status(root).is_valid_and_post_bellatrix());
         } else {
-            assert!(rig.execution_status(root).is_optimistic());
+            assert!(rig.execution_status(root).is_strictly_optimistic());
         }
     }
 }
@@ -605,7 +605,7 @@ async fn latest_valid_hash_will_not_validate() {
         } else if slot == 1 {
             assert!(execution_status.is_valid_and_post_bellatrix())
         } else {
-            assert!(execution_status.is_optimistic())
+            assert!(execution_status.is_strictly_optimistic())
         }
     }
 }
@@ -646,7 +646,7 @@ async fn latest_valid_hash_is_junk() {
         if slot == 1 {
             assert!(rig.execution_status(root).is_valid_and_post_bellatrix());
         } else {
-            assert!(rig.execution_status(root).is_optimistic());
+            assert!(rig.execution_status(root).is_strictly_optimistic());
         }
     }
 }
@@ -734,7 +734,7 @@ async fn invalidates_all_descendants() {
             assert!(execution_status.is_valid_and_post_bellatrix());
         } else if slot <= latest_valid_slot {
             // Blocks prior to and included the latest valid hash are not marked as valid.
-            assert!(execution_status.is_optimistic());
+            assert!(execution_status.is_strictly_optimistic());
         } else {
             // Blocks after the latest valid hash are invalid.
             assert!(execution_status.is_invalid());
@@ -791,7 +791,9 @@ async fn switches_heads() {
     assert_eq!(rig.harness.head_block_root(), fork_block_root);
 
     // The fork block has not yet been validated.
-    assert!(rig.execution_status(fork_block_root).is_optimistic());
+    assert!(rig
+        .execution_status(fork_block_root)
+        .is_strictly_optimistic());
 
     for root in blocks {
         let slot = rig
@@ -816,7 +818,7 @@ async fn switches_heads() {
             assert!(execution_status.is_valid_and_post_bellatrix());
         } else if slot <= latest_valid_slot {
             // Blocks prior to and included the latest valid hash are not marked as valid.
-            assert!(execution_status.is_optimistic());
+            assert!(execution_status.is_strictly_optimistic());
         } else {
             // Blocks after the latest valid hash are invalid.
             assert!(execution_status.is_invalid());
@@ -899,8 +901,8 @@ async fn manually_validate_child() {
     let parent = rig.import_block(Payload::Syncing).await;
     let child = rig.import_block(Payload::Syncing).await;
 
-    assert!(rig.execution_status(parent).is_optimistic());
-    assert!(rig.execution_status(child).is_optimistic());
+    assert!(rig.execution_status(parent).is_strictly_optimistic());
+    assert!(rig.execution_status(child).is_strictly_optimistic());
 
     rig.validate_manually(child);
 
@@ -917,13 +919,13 @@ async fn manually_validate_parent() {
     let parent = rig.import_block(Payload::Syncing).await;
     let child = rig.import_block(Payload::Syncing).await;
 
-    assert!(rig.execution_status(parent).is_optimistic());
-    assert!(rig.execution_status(child).is_optimistic());
+    assert!(rig.execution_status(parent).is_strictly_optimistic());
+    assert!(rig.execution_status(child).is_strictly_optimistic());
 
     rig.validate_manually(parent);
 
     assert!(rig.execution_status(parent).is_valid_and_post_bellatrix());
-    assert!(rig.execution_status(child).is_optimistic());
+    assert!(rig.execution_status(child).is_strictly_optimistic());
 }
 
 #[tokio::test]
@@ -1124,7 +1126,7 @@ async fn attesting_to_optimistic_head() {
         "the head should be the latest imported block"
     );
     assert!(
-        rig.execution_status(root).is_optimistic(),
+        rig.execution_status(root).is_strictly_optimistic(),
         "the head should be optimistic"
     );
 
@@ -1371,7 +1373,7 @@ async fn build_optimistic_chain(
             .chain
             .canonical_head
             .fork_choice_read_lock()
-            .is_optimistic_block(&post_transition_block_root)
+            .is_optimistic_or_invalid_block(&post_transition_block_root)
             .unwrap(),
         "the transition block should be imported optimistically"
     );
@@ -1636,7 +1638,7 @@ async fn optimistic_transition_block_invalid_unfinalized_syncing_ee() {
     // It should still be marked as optimistic.
     assert!(rig
         .execution_status(post_transition_block_root)
-        .is_optimistic());
+        .is_strictly_optimistic());
 
     // the optimistic merge transition block should NOT have been removed from the database
     let otbs = load_optimistic_transition_blocks(&rig.harness.chain)
@@ -1913,8 +1915,9 @@ async fn recover_from_invalid_head_after_persist_and_reboot() {
             .chain
             .canonical_head
             .fork_choice_read_lock()
-            .is_optimistic_block(&resumed_head.head_block_root())
-            .unwrap(),
+            .get_block_execution_status(&resumed_head.head_block_root())
+            .unwrap()
+            .is_strictly_optimistic(),
         "the invalid block should have become optimistic"
     );
 }