Realized unrealized experimentation (#3322)

## Issue Addressed

Add a flag that optionally enables unrealized vote tracking.  Would like to test out on testnets and benchmark differences in methods of vote tracking. This PR includes a DB schema upgrade to enable to new vote tracking style.


Co-authored-by: realbigsean <sean@sigmaprime.io>
Co-authored-by: Paul Hauner <paul@paulhauner.com>
Co-authored-by: sean <seananderson33@gmail.com>
Co-authored-by: Mac L <mjladson@pm.me>

Cargo.lock

@@ -2125,6 +2125,7 @@ dependencies = [
  "eth2_ssz",
  "eth2_ssz_derive",
  "proto_array",
+ "state_processing",
  "store",
  "tokio",
  "types",
@@ -3008,6 +3009,7 @@ dependencies = [
  "serde",
  "serde_json",
  "serde_yaml",
+ "snap",
  "state_processing",
  "tree_hash",
  "types",

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -93,6 +93,7 @@ use types::beacon_state::CloneConfig;
 use types::*;
 
 pub use crate::canonical_head::{CanonicalHead, CanonicalHeadRwLock};
+pub use fork_choice::CountUnrealized;
 
 pub type ForkChoiceError = fork_choice::Error<crate::ForkChoiceStoreError>;
 
@@ -1740,6 +1741,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                 self.slot()?,
                 verified.indexed_attestation(),
                 AttestationFromBlock::False,
+                &self.spec,
             )
             .map_err(Into::into)
     }
@@ -2220,6 +2222,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     pub async fn process_chain_segment(
         self: &Arc<Self>,
         chain_segment: Vec<Arc<SignedBeaconBlock<T::EthSpec>>>,
+        count_unrealized: CountUnrealized,
     ) -> ChainSegmentResult<T::EthSpec> {
         let mut imported_blocks = 0;
 
@@ -2284,7 +2287,10 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
 
             // Import the blocks into the chain.
             for signature_verified_block in signature_verified_blocks {
-                match self.process_block(signature_verified_block).await {
+                match self
+                    .process_block(signature_verified_block, count_unrealized)
+                    .await
+                {
                     Ok(_) => imported_blocks += 1,
                     Err(error) => {
                         return ChainSegmentResult::Failed {
@@ -2368,6 +2374,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     pub async fn process_block<B: IntoExecutionPendingBlock<T>>(
         self: &Arc<Self>,
         unverified_block: B,
+        count_unrealized: CountUnrealized,
     ) -> Result<Hash256, BlockError<T::EthSpec>> {
         // Start the Prometheus timer.
         let _full_timer = metrics::start_timer(&metrics::BLOCK_PROCESSING_TIMES);
@@ -2383,7 +2390,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         let import_block = async move {
             let execution_pending = unverified_block.into_execution_pending_block(&chain)?;
             chain
-                .import_execution_pending_block(execution_pending)
+                .import_execution_pending_block(execution_pending, count_unrealized)
                 .await
         };
 
@@ -2441,6 +2448,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     async fn import_execution_pending_block(
         self: Arc<Self>,
         execution_pending_block: ExecutionPendingBlock<T>,
+        count_unrealized: CountUnrealized,
     ) -> Result<Hash256, BlockError<T::EthSpec>> {
         let ExecutionPendingBlock {
             block,
@@ -2499,6 +2507,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                         state,
                         confirmed_state_roots,
                         payload_verification_status,
+                        count_unrealized,
                     )
                 },
                 "payload_verification_handle",
@@ -2520,6 +2529,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         mut state: BeaconState<T::EthSpec>,
         confirmed_state_roots: Vec<Hash256>,
         payload_verification_status: PayloadVerificationStatus,
+        count_unrealized: CountUnrealized,
     ) -> Result<Hash256, BlockError<T::EthSpec>> {
         let current_slot = self.slot()?;
         let current_epoch = current_slot.epoch(T::EthSpec::slots_per_epoch());
@@ -2665,6 +2675,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                     &state,
                     payload_verification_status,
                     &self.spec,
+                    count_unrealized.and(self.config.count_unrealized.into()),
                 )
                 .map_err(|e| BlockError::BeaconChainError(e.into()))?;
         }
@@ -2690,6 +2701,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                 current_slot,
                 &indexed_attestation,
                 AttestationFromBlock::True,
+                &self.spec,
             ) {
                 Ok(()) => Ok(()),
                 // Ignore invalid attestations whilst importing attestations from a block. The

beacon_node/beacon_chain/src/beacon_fork_choice_store.rs

@@ -155,6 +155,8 @@ pub struct BeaconForkChoiceStore<E: EthSpec, Hot: ItemStore<E>, Cold: ItemStore<
     justified_checkpoint: Checkpoint,
     justified_balances: Vec<u64>,
     best_justified_checkpoint: Checkpoint,
+    unrealized_justified_checkpoint: Checkpoint,
+    unrealized_finalized_checkpoint: Checkpoint,
     proposer_boost_root: Hash256,
     _phantom: PhantomData<E>,
 }
@@ -201,6 +203,8 @@ where
             justified_balances: anchor_state.balances().clone().into(),
             finalized_checkpoint,
             best_justified_checkpoint: justified_checkpoint,
+            unrealized_justified_checkpoint: justified_checkpoint,
+            unrealized_finalized_checkpoint: finalized_checkpoint,
             proposer_boost_root: Hash256::zero(),
             _phantom: PhantomData,
         }
@@ -216,6 +220,8 @@ where
             justified_checkpoint: self.justified_checkpoint,
             justified_balances: self.justified_balances.clone(),
             best_justified_checkpoint: self.best_justified_checkpoint,
+            unrealized_justified_checkpoint: self.unrealized_justified_checkpoint,
+            unrealized_finalized_checkpoint: self.unrealized_finalized_checkpoint,
             proposer_boost_root: self.proposer_boost_root,
         }
     }
@@ -233,6 +239,8 @@ where
             justified_checkpoint: persisted.justified_checkpoint,
             justified_balances: persisted.justified_balances,
             best_justified_checkpoint: persisted.best_justified_checkpoint,
+            unrealized_justified_checkpoint: persisted.unrealized_justified_checkpoint,
+            unrealized_finalized_checkpoint: persisted.unrealized_finalized_checkpoint,
             proposer_boost_root: persisted.proposer_boost_root,
             _phantom: PhantomData,
         })
@@ -280,6 +288,14 @@ where
         &self.finalized_checkpoint
     }
 
+    fn unrealized_justified_checkpoint(&self) -> &Checkpoint {
+        &self.unrealized_justified_checkpoint
+    }
+
+    fn unrealized_finalized_checkpoint(&self) -> &Checkpoint {
+        &self.unrealized_finalized_checkpoint
+    }
+
     fn proposer_boost_root(&self) -> Hash256 {
         self.proposer_boost_root
     }
@@ -323,6 +339,14 @@ where
         self.best_justified_checkpoint = checkpoint
     }
 
+    fn set_unrealized_justified_checkpoint(&mut self, checkpoint: Checkpoint) {
+        self.unrealized_justified_checkpoint = checkpoint;
+    }
+
+    fn set_unrealized_finalized_checkpoint(&mut self, checkpoint: Checkpoint) {
+        self.unrealized_finalized_checkpoint = checkpoint;
+    }
+
     fn set_proposer_boost_root(&mut self, proposer_boost_root: Hash256) {
         self.proposer_boost_root = proposer_boost_root;
     }
@@ -330,22 +354,26 @@ where
 
 /// A container which allows persisting the `BeaconForkChoiceStore` to the on-disk database.
 #[superstruct(
-    variants(V1, V7, V8),
+    variants(V1, V7, V8, V10),
     variant_attributes(derive(Encode, Decode)),
     no_enum
 )]
 pub struct PersistedForkChoiceStore {
     #[superstruct(only(V1, V7))]
     pub balances_cache: BalancesCacheV1,
-    #[superstruct(only(V8))]
+    #[superstruct(only(V8, V10))]
     pub balances_cache: BalancesCacheV8,
     pub time: Slot,
     pub finalized_checkpoint: Checkpoint,
     pub justified_checkpoint: Checkpoint,
     pub justified_balances: Vec<u64>,
     pub best_justified_checkpoint: Checkpoint,
-    #[superstruct(only(V7, V8))]
+    #[superstruct(only(V10))]
+    pub unrealized_justified_checkpoint: Checkpoint,
+    #[superstruct(only(V10))]
+    pub unrealized_finalized_checkpoint: Checkpoint,
+    #[superstruct(only(V7, V8, V10))]
     pub proposer_boost_root: Hash256,
 }
 
-pub type PersistedForkChoiceStore = PersistedForkChoiceStoreV8;
+pub type PersistedForkChoiceStore = PersistedForkChoiceStoreV10;

beacon_node/beacon_chain/src/block_verification.rs

@@ -1416,6 +1416,10 @@ fn check_block_against_finalized_slot<T: BeaconChainTypes>(
     block_root: Hash256,
     chain: &BeaconChain<T>,
 ) -> Result<(), BlockError<T::EthSpec>> {
+    // The finalized checkpoint is being read from fork choice, rather than the cached head.
+    //
+    // Fork choice has the most up-to-date view of finalization and there's no point importing a
+    // block which conflicts with the fork-choice view of finalization.
     let finalized_slot = chain
         .canonical_head
         .cached_head()

beacon_node/beacon_chain/src/builder.rs

@@ -647,6 +647,7 @@ where
                 store.clone(),
                 Some(current_slot),
                 &self.spec,
+                self.chain_config.count_unrealized.into(),
             )?;
         }
 

beacon_node/beacon_chain/src/chain_config.rs

@@ -24,6 +24,7 @@ pub struct ChainConfig {
     ///
     /// If set to 0 then block proposal will not wait for fork choice at all.
     pub fork_choice_before_proposal_timeout_ms: u64,
+    pub count_unrealized: bool,
 }
 
 impl Default for ChainConfig {
@@ -35,6 +36,7 @@ impl Default for ChainConfig {
             enable_lock_timeouts: true,
             max_network_size: 10 * 1_048_576, // 10M
             fork_choice_before_proposal_timeout_ms: DEFAULT_FORK_CHOICE_BEFORE_PROPOSAL_TIMEOUT,
+            count_unrealized: false,
         }
     }
 }

beacon_node/beacon_chain/src/fork_revert.rs

@@ -1,5 +1,5 @@
 use crate::{BeaconForkChoiceStore, BeaconSnapshot};
-use fork_choice::{ForkChoice, PayloadVerificationStatus};
+use fork_choice::{CountUnrealized, ForkChoice, PayloadVerificationStatus};
 use itertools::process_results;
 use slog::{info, warn, Logger};
 use state_processing::state_advance::complete_state_advance;
@@ -99,6 +99,7 @@ pub fn reset_fork_choice_to_finalization<E: EthSpec, Hot: ItemStore<E>, Cold: It
     store: Arc<HotColdDB<E, Hot, Cold>>,
     current_slot: Option<Slot>,
     spec: &ChainSpec,
+    count_unrealized_config: CountUnrealized,
 ) -> Result<ForkChoice<BeaconForkChoiceStore<E, Hot, Cold>, E>, String> {
     // Fetch finalized block.
     let finalized_checkpoint = head_state.finalized_checkpoint();
@@ -163,7 +164,8 @@ pub fn reset_fork_choice_to_finalization<E: EthSpec, Hot: ItemStore<E>, Cold: It
         .map_err(|e| format!("Error loading blocks to replay for fork choice: {:?}", e))?;
 
     let mut state = finalized_snapshot.beacon_state;
-    for block in blocks {
+    let blocks_len = blocks.len();
+    for (i, block) in blocks.into_iter().enumerate() {
         complete_state_advance(&mut state, None, block.slot(), spec)
             .map_err(|e| format!("State advance failed: {:?}", e))?;
 
@@ -183,6 +185,15 @@ pub fn reset_fork_choice_to_finalization<E: EthSpec, Hot: ItemStore<E>, Cold: It
         // This scenario is so rare that it seems OK to double-verify some blocks.
         let payload_verification_status = PayloadVerificationStatus::Optimistic;
 
+        // Because we are replaying a single chain of blocks, we only need to calculate unrealized
+        // justification for the last block in the chain.
+        let is_last_block = i + 1 == blocks_len;
+        let count_unrealized = if is_last_block {
+            count_unrealized_config
+        } else {
+            CountUnrealized::False
+        };
+
         fork_choice
             .on_block(
                 block.slot(),
@@ -193,6 +204,7 @@ pub fn reset_fork_choice_to_finalization<E: EthSpec, Hot: ItemStore<E>, Cold: It
                 &state,
                 payload_verification_status,
                 spec,
+                count_unrealized,
             )
             .map_err(|e| format!("Error applying replayed block to fork choice: {:?}", e))?;
     }

beacon_node/beacon_chain/src/lib.rs

@@ -44,7 +44,7 @@ mod validator_pubkey_cache;
 
 pub use self::beacon_chain::{
     AttestationProcessingOutcome, BeaconChain, BeaconChainTypes, BeaconStore, ChainSegmentResult,
-    ForkChoiceError, ProduceBlockVerification, StateSkipConfig, WhenSlotSkipped,
+    CountUnrealized, ForkChoiceError, ProduceBlockVerification, StateSkipConfig, WhenSlotSkipped,
     INVALID_JUSTIFIED_PAYLOAD_SHUTDOWN_REASON, MAXIMUM_GOSSIP_CLOCK_DISPARITY,
 };
 pub use self::beacon_snapshot::BeaconSnapshot;

beacon_node/beacon_chain/src/persisted_fork_choice.rs

@@ -1,5 +1,6 @@
 use crate::beacon_fork_choice_store::{
-    PersistedForkChoiceStoreV1, PersistedForkChoiceStoreV7, PersistedForkChoiceStoreV8,
+    PersistedForkChoiceStoreV1, PersistedForkChoiceStoreV10, PersistedForkChoiceStoreV7,
+    PersistedForkChoiceStoreV8,
 };
 use ssz::{Decode, Encode};
 use ssz_derive::{Decode, Encode};
@@ -7,10 +8,10 @@ use store::{DBColumn, Error, StoreItem};
 use superstruct::superstruct;
 
 // If adding a new version you should update this type alias and fix the breakages.
-pub type PersistedForkChoice = PersistedForkChoiceV8;
+pub type PersistedForkChoice = PersistedForkChoiceV10;
 
 #[superstruct(
-    variants(V1, V7, V8),
+    variants(V1, V7, V8, V10),
     variant_attributes(derive(Encode, Decode)),
     no_enum
 )]
@@ -22,6 +23,8 @@ pub struct PersistedForkChoice {
     pub fork_choice_store: PersistedForkChoiceStoreV7,
     #[superstruct(only(V8))]
     pub fork_choice_store: PersistedForkChoiceStoreV8,
+    #[superstruct(only(V10))]
+    pub fork_choice_store: PersistedForkChoiceStoreV10,
 }
 
 macro_rules! impl_store_item {
@@ -45,3 +48,4 @@ macro_rules! impl_store_item {
 impl_store_item!(PersistedForkChoiceV1);
 impl_store_item!(PersistedForkChoiceV7);
 impl_store_item!(PersistedForkChoiceV8);
+impl_store_item!(PersistedForkChoiceV10);

beacon_node/beacon_chain/src/schema_change.rs

@@ -1,4 +1,5 @@
 //! Utilities for managing database schema changes.
+mod migration_schema_v10;
 mod migration_schema_v6;
 mod migration_schema_v7;
 mod migration_schema_v8;
@@ -6,7 +7,9 @@ mod migration_schema_v9;
 mod types;
 
 use crate::beacon_chain::{BeaconChainTypes, FORK_CHOICE_DB_KEY};
-use crate::persisted_fork_choice::{PersistedForkChoiceV1, PersistedForkChoiceV7};
+use crate::persisted_fork_choice::{
+    PersistedForkChoiceV1, PersistedForkChoiceV10, PersistedForkChoiceV7, PersistedForkChoiceV8,
+};
 use crate::types::ChainSpec;
 use slog::{warn, Logger};
 use std::path::Path;
@@ -130,6 +133,32 @@ pub fn migrate_schema<T: BeaconChainTypes>(
             migration_schema_v9::downgrade_from_v9::<T>(db.clone(), log)?;
             db.store_schema_version(to)
         }
+        (SchemaVersion(9), SchemaVersion(10)) => {
+            let mut ops = vec![];
+            let fork_choice_opt = db.get_item::<PersistedForkChoiceV8>(&FORK_CHOICE_DB_KEY)?;
+            if let Some(fork_choice) = fork_choice_opt {
+                let updated_fork_choice = migration_schema_v10::update_fork_choice(fork_choice)?;
+
+                ops.push(updated_fork_choice.as_kv_store_op(FORK_CHOICE_DB_KEY));
+            }
+
+            db.store_schema_version_atomically(to, ops)?;
+
+            Ok(())
+        }
+        (SchemaVersion(10), SchemaVersion(9)) => {
+            let mut ops = vec![];
+            let fork_choice_opt = db.get_item::<PersistedForkChoiceV10>(&FORK_CHOICE_DB_KEY)?;
+            if let Some(fork_choice) = fork_choice_opt {
+                let updated_fork_choice = migration_schema_v10::downgrade_fork_choice(fork_choice)?;
+
+                ops.push(updated_fork_choice.as_kv_store_op(FORK_CHOICE_DB_KEY));
+            }
+
+            db.store_schema_version_atomically(to, ops)?;
+
+            Ok(())
+        }
         // Anything else is an error.
         (_, _) => Err(HotColdDBError::UnsupportedSchemaVersion {
             target_version: to,

beacon_node/beacon_chain/src/schema_change/migration_schema_v10.rs

@@ -0,0 +1,97 @@
+use crate::beacon_fork_choice_store::{PersistedForkChoiceStoreV10, PersistedForkChoiceStoreV8};
+use crate::persisted_fork_choice::{PersistedForkChoiceV10, PersistedForkChoiceV8};
+use crate::schema_change::{
+    types::{SszContainerV10, SszContainerV7},
+    StoreError,
+};
+use proto_array::core::SszContainer;
+use ssz::{Decode, Encode};
+
+pub fn update_fork_choice(
+    mut fork_choice: PersistedForkChoiceV8,
+) -> Result<PersistedForkChoiceV10, StoreError> {
+    let ssz_container_v7 = SszContainerV7::from_ssz_bytes(
+        &fork_choice.fork_choice.proto_array_bytes,
+    )
+    .map_err(|e| {
+        StoreError::SchemaMigrationError(format!(
+            "Failed to decode ProtoArrayForkChoice during schema migration: {:?}",
+            e
+        ))
+    })?;
+
+    // These transformations instantiate `node.unrealized_justified_checkpoint` and
+    // `node.unrealized_finalized_checkpoint` to `None`.
+    let ssz_container_v10: SszContainerV10 = ssz_container_v7.into();
+    let ssz_container: SszContainer = ssz_container_v10.into();
+    fork_choice.fork_choice.proto_array_bytes = ssz_container.as_ssz_bytes();
+
+    Ok(fork_choice.into())
+}
+
+pub fn downgrade_fork_choice(
+    mut fork_choice: PersistedForkChoiceV10,
+) -> Result<PersistedForkChoiceV8, StoreError> {
+    let ssz_container_v10 = SszContainerV10::from_ssz_bytes(
+        &fork_choice.fork_choice.proto_array_bytes,
+    )
+    .map_err(|e| {
+        StoreError::SchemaMigrationError(format!(
+            "Failed to decode ProtoArrayForkChoice during schema migration: {:?}",
+            e
+        ))
+    })?;
+
+    let ssz_container_v7: SszContainerV7 = ssz_container_v10.into();
+    fork_choice.fork_choice.proto_array_bytes = ssz_container_v7.as_ssz_bytes();
+
+    Ok(fork_choice.into())
+}
+
+impl From<PersistedForkChoiceStoreV8> for PersistedForkChoiceStoreV10 {
+    fn from(other: PersistedForkChoiceStoreV8) -> Self {
+        Self {
+            balances_cache: other.balances_cache,
+            time: other.time,
+            finalized_checkpoint: other.finalized_checkpoint,
+            justified_checkpoint: other.justified_checkpoint,
+            justified_balances: other.justified_balances,
+            best_justified_checkpoint: other.best_justified_checkpoint,
+            unrealized_justified_checkpoint: other.best_justified_checkpoint,
+            unrealized_finalized_checkpoint: other.finalized_checkpoint,
+            proposer_boost_root: other.proposer_boost_root,
+        }
+    }
+}
+
+impl From<PersistedForkChoiceV8> for PersistedForkChoiceV10 {
+    fn from(other: PersistedForkChoiceV8) -> Self {
+        Self {
+            fork_choice: other.fork_choice,
+            fork_choice_store: other.fork_choice_store.into(),
+        }
+    }
+}
+
+impl From<PersistedForkChoiceStoreV10> for PersistedForkChoiceStoreV8 {
+    fn from(other: PersistedForkChoiceStoreV10) -> Self {
+        Self {
+            balances_cache: other.balances_cache,
+            time: other.time,
+            finalized_checkpoint: other.finalized_checkpoint,
+            justified_checkpoint: other.justified_checkpoint,
+            justified_balances: other.justified_balances,
+            best_justified_checkpoint: other.best_justified_checkpoint,
+            proposer_boost_root: other.proposer_boost_root,
+        }
+    }
+}
+
+impl From<PersistedForkChoiceV10> for PersistedForkChoiceV8 {
+    fn from(other: PersistedForkChoiceV10) -> Self {
+        Self {
+            fork_choice: other.fork_choice,
+            fork_choice_store: other.fork_choice_store.into(),
+        }
+    }
+}

beacon_node/beacon_chain/src/schema_change/migration_schema_v7.rs

@@ -2,7 +2,7 @@
 use crate::beacon_chain::BeaconChainTypes;
 use crate::beacon_fork_choice_store::{PersistedForkChoiceStoreV1, PersistedForkChoiceStoreV7};
 use crate::persisted_fork_choice::{PersistedForkChoiceV1, PersistedForkChoiceV7};
-use crate::schema_change::types::{ProtoNodeV6, SszContainerV6, SszContainerV7};
+use crate::schema_change::types::{ProtoNodeV6, SszContainerV10, SszContainerV6, SszContainerV7};
 use crate::types::{ChainSpec, Checkpoint, Epoch, EthSpec, Hash256, Slot};
 use crate::{BeaconForkChoiceStore, BeaconSnapshot};
 use fork_choice::ForkChoice;
@@ -86,7 +86,8 @@ pub(crate) fn update_fork_choice<T: BeaconChainTypes>(
     // to `None`.
     let ssz_container_v7: SszContainerV7 =
         ssz_container_v6.into_ssz_container_v7(justified_checkpoint, finalized_checkpoint);
-    let ssz_container: SszContainer = ssz_container_v7.into();
+    let ssz_container_v10: SszContainerV10 = ssz_container_v7.into();
+    let ssz_container: SszContainer = ssz_container_v10.into();
     let mut fork_choice: ProtoArrayForkChoice = ssz_container.into();
 
     update_checkpoints::<T>(finalized_checkpoint.root, &nodes_v6, &mut fork_choice, db)
@@ -97,6 +98,13 @@ pub(crate) fn update_fork_choice<T: BeaconChainTypes>(
     update_store_justified_checkpoint(persisted_fork_choice, &mut fork_choice)
         .map_err(StoreError::SchemaMigrationError)?;
 
+    // Need to downgrade the SSZ container to V7 so that all migrations can be applied in sequence.
+    let ssz_container = SszContainer::from(&fork_choice);
+    let ssz_container_v7 = SszContainerV7::from(ssz_container);
+
+    persisted_fork_choice.fork_choice.proto_array_bytes = ssz_container_v7.as_ssz_bytes();
+    persisted_fork_choice.fork_choice_store.justified_checkpoint = justified_checkpoint;
+
     Ok(())
 }
 
@@ -301,8 +309,6 @@ fn update_store_justified_checkpoint(
         .ok_or("Proto node with current finalized checkpoint not found")?;
 
     fork_choice.core_proto_array_mut().justified_checkpoint = justified_checkpoint;
-    persisted_fork_choice.fork_choice.proto_array_bytes = fork_choice.as_bytes();
-    persisted_fork_choice.fork_choice_store.justified_checkpoint = justified_checkpoint;
     Ok(())
 }
 

beacon_node/beacon_chain/src/schema_change/types.rs

@@ -12,7 +12,7 @@ four_byte_option_impl!(four_byte_option_usize, usize);
 four_byte_option_impl!(four_byte_option_checkpoint, Checkpoint);
 
 #[superstruct(
-    variants(V1, V6, V7),
+    variants(V1, V6, V7, V10),
     variant_attributes(derive(Clone, PartialEq, Debug, Encode, Decode)),
     no_enum
 )]
@@ -30,18 +30,24 @@ pub struct ProtoNode {
     #[superstruct(only(V1, V6))]
     pub finalized_epoch: Epoch,
     #[ssz(with = "four_byte_option_checkpoint")]
-    #[superstruct(only(V7))]
+    #[superstruct(only(V7, V10))]
     pub justified_checkpoint: Option<Checkpoint>,
     #[ssz(with = "four_byte_option_checkpoint")]
-    #[superstruct(only(V7))]
+    #[superstruct(only(V7, V10))]
     pub finalized_checkpoint: Option<Checkpoint>,
     pub weight: u64,
     #[ssz(with = "four_byte_option_usize")]
     pub best_child: Option<usize>,
     #[ssz(with = "four_byte_option_usize")]
     pub best_descendant: Option<usize>,
-    #[superstruct(only(V6, V7))]
+    #[superstruct(only(V6, V7, V10))]
     pub execution_status: ExecutionStatus,
+    #[ssz(with = "four_byte_option_checkpoint")]
+    #[superstruct(only(V10))]
+    pub unrealized_justified_checkpoint: Option<Checkpoint>,
+    #[ssz(with = "four_byte_option_checkpoint")]
+    #[superstruct(only(V10))]
+    pub unrealized_finalized_checkpoint: Option<Checkpoint>,
 }
 
 impl Into<ProtoNodeV6> for ProtoNodeV1 {
@@ -88,9 +94,31 @@ impl Into<ProtoNodeV7> for ProtoNodeV6 {
     }
 }
 
-impl Into<ProtoNode> for ProtoNodeV7 {
+impl Into<ProtoNodeV10> for ProtoNodeV7 {
-    fn into(self) -> ProtoNode {
+    fn into(self) -> ProtoNodeV10 {
-        ProtoNode {
+        ProtoNodeV10 {
+            slot: self.slot,
+            state_root: self.state_root,
+            target_root: self.target_root,
+            current_epoch_shuffling_id: self.current_epoch_shuffling_id,
+            next_epoch_shuffling_id: self.next_epoch_shuffling_id,
+            root: self.root,
+            parent: self.parent,
+            justified_checkpoint: self.justified_checkpoint,
+            finalized_checkpoint: self.finalized_checkpoint,
+            weight: self.weight,
+            best_child: self.best_child,
+            best_descendant: self.best_descendant,
+            execution_status: self.execution_status,
+            unrealized_justified_checkpoint: None,
+            unrealized_finalized_checkpoint: None,
+        }
+    }
+}
+
+impl Into<ProtoNodeV7> for ProtoNodeV10 {
+    fn into(self) -> ProtoNodeV7 {
+        ProtoNodeV7 {
             slot: self.slot,
             state_root: self.state_root,
             target_root: self.target_root,
@@ -108,8 +136,50 @@ impl Into<ProtoNode> for ProtoNodeV7 {
     }
 }
 
+impl Into<ProtoNode> for ProtoNodeV10 {
+    fn into(self) -> ProtoNode {
+        ProtoNode {
+            slot: self.slot,
+            state_root: self.state_root,
+            target_root: self.target_root,
+            current_epoch_shuffling_id: self.current_epoch_shuffling_id,
+            next_epoch_shuffling_id: self.next_epoch_shuffling_id,
+            root: self.root,
+            parent: self.parent,
+            justified_checkpoint: self.justified_checkpoint,
+            finalized_checkpoint: self.finalized_checkpoint,
+            weight: self.weight,
+            best_child: self.best_child,
+            best_descendant: self.best_descendant,
+            execution_status: self.execution_status,
+            unrealized_justified_checkpoint: self.unrealized_justified_checkpoint,
+            unrealized_finalized_checkpoint: self.unrealized_finalized_checkpoint,
+        }
+    }
+}
+
+impl From<ProtoNode> for ProtoNodeV7 {
+    fn from(container: ProtoNode) -> Self {
+        Self {
+            slot: container.slot,
+            state_root: container.state_root,
+            target_root: container.target_root,
+            current_epoch_shuffling_id: container.current_epoch_shuffling_id,
+            next_epoch_shuffling_id: container.next_epoch_shuffling_id,
+            root: container.root,
+            parent: container.parent,
+            justified_checkpoint: container.justified_checkpoint,
+            finalized_checkpoint: container.finalized_checkpoint,
+            weight: container.weight,
+            best_child: container.best_child,
+            best_descendant: container.best_descendant,
+            execution_status: container.execution_status,
+        }
+    }
+}
+
 #[superstruct(
-    variants(V1, V6, V7),
+    variants(V1, V6, V7, V10),
     variant_attributes(derive(Encode, Decode)),
     no_enum
 )]
@@ -122,9 +192,9 @@ pub struct SszContainer {
     pub justified_epoch: Epoch,
     #[superstruct(only(V1, V6))]
     pub finalized_epoch: Epoch,
-    #[superstruct(only(V7))]
+    #[superstruct(only(V7, V10))]
     pub justified_checkpoint: Checkpoint,
-    #[superstruct(only(V7))]
+    #[superstruct(only(V7, V10))]
     pub finalized_checkpoint: Checkpoint,
     #[superstruct(only(V1))]
     pub nodes: Vec<ProtoNodeV1>,
@@ -132,8 +202,10 @@ pub struct SszContainer {
     pub nodes: Vec<ProtoNodeV6>,
     #[superstruct(only(V7))]
     pub nodes: Vec<ProtoNodeV7>,
+    #[superstruct(only(V10))]
+    pub nodes: Vec<ProtoNodeV10>,
     pub indices: Vec<(Hash256, usize)>,
-    #[superstruct(only(V7))]
+    #[superstruct(only(V7, V10))]
     pub previous_proposer_boost: ProposerBoost,
 }
 
@@ -174,7 +246,41 @@ impl SszContainerV6 {
     }
 }
 
-impl Into<SszContainer> for SszContainerV7 {
+impl Into<SszContainerV10> for SszContainerV7 {
+    fn into(self) -> SszContainerV10 {
+        let nodes = self.nodes.into_iter().map(Into::into).collect();
+
+        SszContainerV10 {
+            votes: self.votes,
+            balances: self.balances,
+            prune_threshold: self.prune_threshold,
+            justified_checkpoint: self.justified_checkpoint,
+            finalized_checkpoint: self.finalized_checkpoint,
+            nodes,
+            indices: self.indices,
+            previous_proposer_boost: self.previous_proposer_boost,
+        }
+    }
+}
+
+impl Into<SszContainerV7> for SszContainerV10 {
+    fn into(self) -> SszContainerV7 {
+        let nodes = self.nodes.into_iter().map(Into::into).collect();
+
+        SszContainerV7 {
+            votes: self.votes,
+            balances: self.balances,
+            prune_threshold: self.prune_threshold,
+            justified_checkpoint: self.justified_checkpoint,
+            finalized_checkpoint: self.finalized_checkpoint,
+            nodes,
+            indices: self.indices,
+            previous_proposer_boost: self.previous_proposer_boost,
+        }
+    }
+}
+
+impl Into<SszContainer> for SszContainerV10 {
     fn into(self) -> SszContainer {
         let nodes = self.nodes.into_iter().map(Into::into).collect();
 
@@ -190,3 +296,20 @@ impl Into<SszContainer> for SszContainerV7 {
         }
     }
 }
+
+impl From<SszContainer> for SszContainerV7 {
+    fn from(container: SszContainer) -> Self {
+        let nodes = container.nodes.into_iter().map(Into::into).collect();
+
+        Self {
+            votes: container.votes,
+            balances: container.balances,
+            prune_threshold: container.prune_threshold,
+            justified_checkpoint: container.justified_checkpoint,
+            finalized_checkpoint: container.finalized_checkpoint,
+            nodes,
+            indices: container.indices,
+            previous_proposer_boost: container.previous_proposer_boost,
+        }
+    }
+}

beacon_node/beacon_chain/src/test_utils.rs

@@ -17,6 +17,7 @@ use execution_layer::{
     test_utils::{ExecutionBlockGenerator, MockExecutionLayer, DEFAULT_TERMINAL_BLOCK},
     ExecutionLayer,
 };
+use fork_choice::CountUnrealized;
 use futures::channel::mpsc::Receiver;
 pub use genesis::{interop_genesis_state, DEFAULT_ETH1_BLOCK_HASH};
 use int_to_bytes::int_to_bytes32;
@@ -1370,8 +1371,11 @@ where
         block: SignedBeaconBlock<E>,
     ) -> Result<SignedBeaconBlockHash, BlockError<E>> {
         self.set_current_slot(slot);
-        let block_hash: SignedBeaconBlockHash =
+        let block_hash: SignedBeaconBlockHash = self
-            self.chain.process_block(Arc::new(block)).await?.into();
+            .chain
+            .process_block(Arc::new(block), CountUnrealized::True)
+            .await?
+            .into();
         self.chain.recompute_head_at_current_slot().await?;
         Ok(block_hash)
     }
@@ -1380,8 +1384,11 @@ where
         &self,
         block: SignedBeaconBlock<E>,
     ) -> Result<SignedBeaconBlockHash, BlockError<E>> {
-        let block_hash: SignedBeaconBlockHash =
+        let block_hash: SignedBeaconBlockHash = self
-            self.chain.process_block(Arc::new(block)).await?.into();
+            .chain
+            .process_block(Arc::new(block), CountUnrealized::True)
+            .await?
+            .into();
         self.chain.recompute_head_at_current_slot().await?;
         Ok(block_hash)
     }

beacon_node/beacon_chain/tests/block_verification.rs

@@ -4,6 +4,7 @@ use beacon_chain::test_utils::{
     AttestationStrategy, BeaconChainHarness, BlockStrategy, EphemeralHarnessType,
 };
 use beacon_chain::{BeaconSnapshot, BlockError, ChainSegmentResult};
+use fork_choice::CountUnrealized;
 use lazy_static::lazy_static;
 use logging::test_logger;
 use slasher::{Config as SlasherConfig, Slasher};
@@ -147,14 +148,14 @@ async fn chain_segment_full_segment() {
     // Sneak in a little check to ensure we can process empty chain segments.
     harness
         .chain
-        .process_chain_segment(vec![])
+        .process_chain_segment(vec![], CountUnrealized::True)
         .await
         .into_block_error()
         .expect("should import empty chain segment");
 
     harness
         .chain
-        .process_chain_segment(blocks.clone())
+        .process_chain_segment(blocks.clone(), CountUnrealized::True)
         .await
         .into_block_error()
         .expect("should import chain segment");
@@ -187,7 +188,7 @@ async fn chain_segment_varying_chunk_size() {
         for chunk in blocks.chunks(*chunk_size) {
             harness
                 .chain
-                .process_chain_segment(chunk.to_vec())
+                .process_chain_segment(chunk.to_vec(), CountUnrealized::True)
                 .await
                 .into_block_error()
                 .unwrap_or_else(|_| panic!("should import chain segment of len {}", chunk_size));
@@ -227,7 +228,7 @@ async fn chain_segment_non_linear_parent_roots() {
         matches!(
             harness
                 .chain
-                .process_chain_segment(blocks)
+                .process_chain_segment(blocks, CountUnrealized::True)
                 .await
                 .into_block_error(),
             Err(BlockError::NonLinearParentRoots)
@@ -247,7 +248,7 @@ async fn chain_segment_non_linear_parent_roots() {
         matches!(
             harness
                 .chain
-                .process_chain_segment(blocks)
+                .process_chain_segment(blocks, CountUnrealized::True)
                 .await
                 .into_block_error(),
             Err(BlockError::NonLinearParentRoots)
@@ -278,7 +279,7 @@ async fn chain_segment_non_linear_slots() {
         matches!(
             harness
                 .chain
-                .process_chain_segment(blocks)
+                .process_chain_segment(blocks, CountUnrealized::True)
                 .await
                 .into_block_error(),
             Err(BlockError::NonLinearSlots)
@@ -299,7 +300,7 @@ async fn chain_segment_non_linear_slots() {
         matches!(
             harness
                 .chain
-                .process_chain_segment(blocks)
+                .process_chain_segment(blocks, CountUnrealized::True)
                 .await
                 .into_block_error(),
             Err(BlockError::NonLinearSlots)
@@ -325,7 +326,7 @@ async fn assert_invalid_signature(
         matches!(
             harness
                 .chain
-                .process_chain_segment(blocks)
+                .process_chain_segment(blocks, CountUnrealized::True)
                 .await
                 .into_block_error(),
             Err(BlockError::InvalidSignature)
@@ -342,12 +343,18 @@ async fn assert_invalid_signature(
         .collect();
     // We don't care if this fails, we just call this to ensure that all prior blocks have been
     // imported prior to this test.
-    let _ = harness.chain.process_chain_segment(ancestor_blocks).await;
+    let _ = harness
+        .chain
+        .process_chain_segment(ancestor_blocks, CountUnrealized::True)
+        .await;
     assert!(
         matches!(
             harness
                 .chain
-                .process_block(snapshots[block_index].beacon_block.clone())
+                .process_block(
+                    snapshots[block_index].beacon_block.clone(),
+                    CountUnrealized::True
+                )
                 .await,
             Err(BlockError::InvalidSignature)
         ),
@@ -397,7 +404,7 @@ async fn invalid_signature_gossip_block() {
             .collect();
         harness
             .chain
-            .process_chain_segment(ancestor_blocks)
+            .process_chain_segment(ancestor_blocks, CountUnrealized::True)
             .await
             .into_block_error()
             .expect("should import all blocks prior to the one being tested");
@@ -405,10 +412,10 @@ async fn invalid_signature_gossip_block() {
             matches!(
                 harness
                     .chain
-                    .process_block(Arc::new(SignedBeaconBlock::from_block(
+                    .process_block(
-                        block,
+                        Arc::new(SignedBeaconBlock::from_block(block, junk_signature())),
-                        junk_signature()
+                        CountUnrealized::True
-                    )))
+                    )
                     .await,
                 Err(BlockError::InvalidSignature)
             ),
@@ -441,7 +448,7 @@ async fn invalid_signature_block_proposal() {
             matches!(
                 harness
                     .chain
-                    .process_chain_segment(blocks)
+                    .process_chain_segment(blocks, CountUnrealized::True)
                     .await
                     .into_block_error(),
                 Err(BlockError::InvalidSignature)
@@ -639,7 +646,7 @@ async fn invalid_signature_deposit() {
             !matches!(
                 harness
                     .chain
-                    .process_chain_segment(blocks)
+                    .process_chain_segment(blocks, CountUnrealized::True)
                     .await
                     .into_block_error(),
                 Err(BlockError::InvalidSignature)
@@ -716,11 +723,18 @@ async fn block_gossip_verification() {
 
         harness
             .chain
-            .process_block(gossip_verified)
+            .process_block(gossip_verified, CountUnrealized::True)
             .await
             .expect("should import valid gossip verified block");
     }
 
+    // Recompute the head to ensure we cache the latest view of fork choice.
+    harness
+        .chain
+        .recompute_head_at_current_slot()
+        .await
+        .unwrap();
+
     /*
      * This test ensures that:
      *
@@ -978,7 +992,11 @@ async fn verify_block_for_gossip_slashing_detection() {
         .verify_block_for_gossip(Arc::new(block1))
         .await
         .unwrap();
-    harness.chain.process_block(verified_block).await.unwrap();
+    harness
+        .chain
+        .process_block(verified_block, CountUnrealized::True)
+        .await
+        .unwrap();
     unwrap_err(
         harness
             .chain
@@ -1009,7 +1027,11 @@ async fn verify_block_for_gossip_doppelganger_detection() {
         .await
         .unwrap();
     let attestations = verified_block.block.message().body().attestations().clone();
-    harness.chain.process_block(verified_block).await.unwrap();
+    harness
+        .chain
+        .process_block(verified_block, CountUnrealized::True)
+        .await
+        .unwrap();
 
     for att in attestations.iter() {
         let epoch = att.data.target.epoch;
@@ -1148,7 +1170,7 @@ async fn add_base_block_to_altair_chain() {
     assert!(matches!(
         harness
             .chain
-            .process_block(Arc::new(base_block.clone()))
+            .process_block(Arc::new(base_block.clone()), CountUnrealized::True)
             .await
             .err()
             .expect("should error when processing base block"),
@@ -1162,7 +1184,7 @@ async fn add_base_block_to_altair_chain() {
     assert!(matches!(
         harness
             .chain
-            .process_chain_segment(vec![Arc::new(base_block)])
+            .process_chain_segment(vec![Arc::new(base_block)], CountUnrealized::True)
             .await,
         ChainSegmentResult::Failed {
             imported_blocks: 0,
@@ -1276,7 +1298,7 @@ async fn add_altair_block_to_base_chain() {
     assert!(matches!(
         harness
             .chain
-            .process_block(Arc::new(altair_block.clone()))
+            .process_block(Arc::new(altair_block.clone()), CountUnrealized::True)
             .await
             .err()
             .expect("should error when processing altair block"),
@@ -1290,7 +1312,7 @@ async fn add_altair_block_to_base_chain() {
     assert!(matches!(
         harness
             .chain
-            .process_chain_segment(vec![Arc::new(altair_block)])
+            .process_chain_segment(vec![Arc::new(altair_block)], CountUnrealized::True)
             .await,
         ChainSegmentResult::Failed {
             imported_blocks: 0,

beacon_node/beacon_chain/tests/payload_invalidation.rs

@@ -9,7 +9,9 @@ use execution_layer::{
     json_structures::{JsonForkChoiceStateV1, JsonPayloadAttributesV1},
     ExecutionLayer, ForkChoiceState, PayloadAttributes,
 };
-use fork_choice::{Error as ForkChoiceError, InvalidationOperation, PayloadVerificationStatus};
+use fork_choice::{
+    CountUnrealized, Error as ForkChoiceError, InvalidationOperation, PayloadVerificationStatus,
+};
 use proto_array::{Error as ProtoArrayError, ExecutionStatus};
 use slot_clock::SlotClock;
 use std::sync::Arc;
@@ -648,7 +650,7 @@ async fn invalidates_all_descendants() {
     let fork_block_root = rig
         .harness
         .chain
-        .process_block(Arc::new(fork_block))
+        .process_block(Arc::new(fork_block), CountUnrealized::True)
         .await
         .unwrap();
     rig.recompute_head().await;
@@ -740,7 +742,7 @@ async fn switches_heads() {
     let fork_block_root = rig
         .harness
         .chain
-        .process_block(Arc::new(fork_block))
+        .process_block(Arc::new(fork_block), CountUnrealized::True)
         .await
         .unwrap();
     rig.recompute_head().await;
@@ -984,7 +986,7 @@ async fn invalid_parent() {
 
     // Ensure the block built atop an invalid payload is invalid for import.
     assert!(matches!(
-        rig.harness.chain.process_block(block.clone()).await,
+        rig.harness.chain.process_block(block.clone(), CountUnrealized::True).await,
         Err(BlockError::ParentExecutionPayloadInvalid { parent_root: invalid_root })
         if invalid_root == parent_root
     ));
@@ -998,7 +1000,8 @@ async fn invalid_parent() {
             Duration::from_secs(0),
             &state,
             PayloadVerificationStatus::Optimistic,
-            &rig.harness.chain.spec
+            &rig.harness.chain.spec,
+            CountUnrealized::True,
         ),
         Err(ForkChoiceError::ProtoArrayError(message))
         if message.contains(&format!(

beacon_node/beacon_chain/tests/store_tests.rs

@@ -10,6 +10,7 @@ use beacon_chain::{
     BeaconChainError, BeaconChainTypes, BeaconSnapshot, ChainConfig, ServerSentEventHandler,
     WhenSlotSkipped,
 };
+use fork_choice::CountUnrealized;
 use lazy_static::lazy_static;
 use logging::test_logger;
 use maplit::hashset;
@@ -2124,7 +2125,7 @@ async fn weak_subjectivity_sync() {
 
         beacon_chain.slot_clock.set_slot(block.slot().as_u64());
         beacon_chain
-            .process_block(Arc::new(full_block))
+            .process_block(Arc::new(full_block), CountUnrealized::True)
             .await
             .unwrap();
         beacon_chain.recompute_head_at_current_slot().await.unwrap();

beacon_node/beacon_chain/tests/tests.rs

@@ -8,6 +8,7 @@ use beacon_chain::{
     },
     BeaconChain, StateSkipConfig, WhenSlotSkipped,
 };
+use fork_choice::CountUnrealized;
 use lazy_static::lazy_static;
 use operation_pool::PersistedOperationPool;
 use state_processing::{
@@ -499,7 +500,7 @@ async fn unaggregated_attestations_added_to_fork_choice_some_none() {
     // Move forward a slot so all queued attestations can be processed.
     harness.advance_slot();
     fork_choice
-        .update_time(harness.chain.slot().unwrap())
+        .update_time(harness.chain.slot().unwrap(), &harness.chain.spec)
         .unwrap();
 
     let validator_slots: Vec<(usize, Slot)> = (0..VALIDATOR_COUNT)
@@ -613,7 +614,7 @@ async fn unaggregated_attestations_added_to_fork_choice_all_updated() {
     // Move forward a slot so all queued attestations can be processed.
     harness.advance_slot();
     fork_choice
-        .update_time(harness.chain.slot().unwrap())
+        .update_time(harness.chain.slot().unwrap(), &harness.chain.spec)
         .unwrap();
 
     let validators: Vec<usize> = (0..VALIDATOR_COUNT).collect();
@@ -683,7 +684,10 @@ async fn run_skip_slot_test(skip_slots: u64) {
     assert_eq!(
         harness_b
             .chain
-            .process_block(harness_a.chain.head_snapshot().beacon_block.clone())
+            .process_block(
+                harness_a.chain.head_snapshot().beacon_block.clone(),
+                CountUnrealized::True
+            )
             .await
             .unwrap(),
         harness_a.chain.head_snapshot().beacon_block_root

beacon_node/http_api/src/lib.rs

@@ -23,7 +23,7 @@ use beacon_chain::{
     observed_operations::ObservationOutcome,
     validator_monitor::{get_block_delay_ms, timestamp_now},
     AttestationError as AttnError, BeaconChain, BeaconChainError, BeaconChainTypes,
-    ProduceBlockVerification, WhenSlotSkipped,
+    CountUnrealized, ProduceBlockVerification, WhenSlotSkipped,
 };
 pub use block_id::BlockId;
 use eth2::types::{self as api_types, EndpointVersion, ValidatorId};
@@ -1035,7 +1035,10 @@ pub fn serve<T: BeaconChainTypes>(
                 let delay = get_block_delay_ms(seen_timestamp, block.message(), &chain.slot_clock);
                 metrics::observe_duration(&metrics::HTTP_API_BLOCK_BROADCAST_DELAY_TIMES, delay);
 
-                match chain.process_block(block.clone()).await {
+                match chain
+                    .process_block(block.clone(), CountUnrealized::True)
+                    .await
+                {
                     Ok(root) => {
                         info!(
                             log,
@@ -1179,7 +1182,7 @@ pub fn serve<T: BeaconChainTypes>(
                         PubsubMessage::BeaconBlock(new_block.clone()),
                     )?;
 
-                    match chain.process_block(new_block).await {
+                    match chain.process_block(new_block, CountUnrealized::True).await {
                         Ok(_) => {
                             // Update the head since it's likely this block will become the new
                             // head.

beacon_node/network/src/beacon_processor/worker/gossip_methods.rs

@@ -6,7 +6,8 @@ use beacon_chain::{
     observed_operations::ObservationOutcome,
     sync_committee_verification::{self, Error as SyncCommitteeError},
     validator_monitor::get_block_delay_ms,
-    BeaconChainError, BeaconChainTypes, BlockError, ForkChoiceError, GossipVerifiedBlock,
+    BeaconChainError, BeaconChainTypes, BlockError, CountUnrealized, ForkChoiceError,
+    GossipVerifiedBlock,
 };
 use lighthouse_network::{Client, MessageAcceptance, MessageId, PeerAction, PeerId, ReportSource};
 use slog::{crit, debug, error, info, trace, warn};
@@ -899,7 +900,11 @@ impl<T: BeaconChainTypes> Worker<T> {
     ) {
         let block: Arc<_> = verified_block.block.clone();
 
-        match self.chain.process_block(verified_block).await {
+        match self
+            .chain
+            .process_block(verified_block, CountUnrealized::True)
+            .await
+        {
             Ok(block_root) => {
                 metrics::inc_counter(&metrics::BEACON_PROCESSOR_GOSSIP_BLOCK_IMPORTED_TOTAL);
 

beacon_node/network/src/beacon_processor/worker/sync_methods.rs

@@ -7,10 +7,10 @@ use crate::beacon_processor::DuplicateCache;
 use crate::metrics;
 use crate::sync::manager::{BlockProcessType, SyncMessage};
 use crate::sync::{BatchProcessResult, ChainId};
-use beacon_chain::ExecutionPayloadError;
 use beacon_chain::{
     BeaconChainError, BeaconChainTypes, BlockError, ChainSegmentResult, HistoricalBlockError,
 };
+use beacon_chain::{CountUnrealized, ExecutionPayloadError};
 use lighthouse_network::PeerAction;
 use slog::{debug, error, info, warn};
 use std::sync::Arc;
@@ -21,7 +21,7 @@ use types::{Epoch, Hash256, SignedBeaconBlock};
 #[derive(Clone, Debug, PartialEq)]
 pub enum ChainSegmentProcessId {
     /// Processing Id of a range syncing batch.
-    RangeBatchId(ChainId, Epoch),
+    RangeBatchId(ChainId, Epoch, CountUnrealized),
     /// Processing ID for a backfill syncing batch.
     BackSyncBatchId(Epoch),
     /// Processing Id of the parent lookup of a block.
@@ -89,7 +89,7 @@ impl<T: BeaconChainTypes> Worker<T> {
             }
         };
         let slot = block.slot();
-        let result = self.chain.process_block(block).await;
+        let result = self.chain.process_block(block, CountUnrealized::True).await;
 
         metrics::inc_counter(&metrics::BEACON_PROCESSOR_RPC_BLOCK_IMPORTED_TOTAL);
 
@@ -133,12 +133,15 @@ impl<T: BeaconChainTypes> Worker<T> {
     ) {
         let result = match sync_type {
             // this a request from the range sync
-            ChainSegmentProcessId::RangeBatchId(chain_id, epoch) => {
+            ChainSegmentProcessId::RangeBatchId(chain_id, epoch, count_unrealized) => {
                 let start_slot = downloaded_blocks.first().map(|b| b.slot().as_u64());
                 let end_slot = downloaded_blocks.last().map(|b| b.slot().as_u64());
                 let sent_blocks = downloaded_blocks.len();
 
-                match self.process_blocks(downloaded_blocks.iter()).await {
+                match self
+                    .process_blocks(downloaded_blocks.iter(), count_unrealized)
+                    .await
+                {
                     (_, Ok(_)) => {
                         debug!(self.log, "Batch processed";
                             "batch_epoch" => epoch,
@@ -207,7 +210,10 @@ impl<T: BeaconChainTypes> Worker<T> {
                 );
                 // parent blocks are ordered from highest slot to lowest, so we need to process in
                 // reverse
-                match self.process_blocks(downloaded_blocks.iter().rev()).await {
+                match self
+                    .process_blocks(downloaded_blocks.iter().rev(), CountUnrealized::True)
+                    .await
+                {
                     (imported_blocks, Err(e)) => {
                         debug!(self.log, "Parent lookup failed"; "error" => %e.message);
                         BatchProcessResult::Failed {
@@ -231,9 +237,14 @@ impl<T: BeaconChainTypes> Worker<T> {
     async fn process_blocks<'a>(
         &self,
         downloaded_blocks: impl Iterator<Item = &'a Arc<SignedBeaconBlock<T::EthSpec>>>,
+        count_unrealized: CountUnrealized,
     ) -> (usize, Result<(), ChainSegmentFailed>) {
         let blocks: Vec<Arc<_>> = downloaded_blocks.cloned().collect();
-        match self.chain.process_chain_segment(blocks).await {
+        match self
+            .chain
+            .process_chain_segment(blocks, count_unrealized)
+            .await
+        {
             ChainSegmentResult::Successful { imported_blocks } => {
                 metrics::inc_counter(&metrics::BEACON_PROCESSOR_CHAIN_SEGMENT_SUCCESS_TOTAL);
                 if imported_blocks > 0 {

beacon_node/network/src/sync/manager.rs

@@ -532,7 +532,7 @@ impl<T: BeaconChainTypes> SyncManager<T> {
                             .parent_block_processed(chain_hash, result, &mut self.network),
                     },
                     SyncMessage::BatchProcessed { sync_type, result } => match sync_type {
-                        ChainSegmentProcessId::RangeBatchId(chain_id, epoch) => {
+                        ChainSegmentProcessId::RangeBatchId(chain_id, epoch, _) => {
                             self.range_sync.handle_block_process_result(
                                 &mut self.network,
                                 chain_id,

beacon_node/network/src/sync/range_sync/chain.rs

@@ -2,7 +2,7 @@ use super::batch::{BatchInfo, BatchProcessingResult, BatchState};
 use crate::beacon_processor::WorkEvent as BeaconWorkEvent;
 use crate::beacon_processor::{ChainSegmentProcessId, FailureMode};
 use crate::sync::{manager::Id, network_context::SyncNetworkContext, BatchProcessResult};
-use beacon_chain::BeaconChainTypes;
+use beacon_chain::{BeaconChainTypes, CountUnrealized};
 use fnv::FnvHashMap;
 use lighthouse_network::{PeerAction, PeerId};
 use rand::seq::SliceRandom;
@@ -100,6 +100,8 @@ pub struct SyncingChain<T: BeaconChainTypes> {
     /// A multi-threaded, non-blocking processor for applying messages to the beacon chain.
     beacon_processor_send: Sender<BeaconWorkEvent<T>>,
 
+    is_finalized_segment: bool,
+
     /// The chain's log.
     log: slog::Logger,
 }
@@ -126,6 +128,7 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
         target_head_root: Hash256,
         peer_id: PeerId,
         beacon_processor_send: Sender<BeaconWorkEvent<T>>,
+        is_finalized_segment: bool,
         log: &slog::Logger,
     ) -> Self {
         let mut peers = FnvHashMap::default();
@@ -148,6 +151,7 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
             current_processing_batch: None,
             validated_batches: 0,
             beacon_processor_send,
+            is_finalized_segment,
             log: log.new(o!("chain" => id)),
         }
     }
@@ -302,7 +306,12 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
         // for removing chains and checking completion is in the callback.
 
         let blocks = batch.start_processing()?;
-        let process_id = ChainSegmentProcessId::RangeBatchId(self.id, batch_id);
+        let count_unrealized = if self.is_finalized_segment {
+            CountUnrealized::False
+        } else {
+            CountUnrealized::True
+        };
+        let process_id = ChainSegmentProcessId::RangeBatchId(self.id, batch_id, count_unrealized);
         self.current_processing_batch = Some(batch_id);
 
         if let Err(e) = self

beacon_node/network/src/sync/range_sync/chain_collection.rs

@@ -472,10 +472,10 @@ impl<T: BeaconChainTypes, C: BlockStorage> ChainCollection<T, C> {
         network: &mut SyncNetworkContext<T::EthSpec>,
     ) {
         let id = SyncingChain::<T>::id(&target_head_root, &target_head_slot);
-        let collection = if let RangeSyncType::Finalized = sync_type {
+        let (collection, is_finalized) = if let RangeSyncType::Finalized = sync_type {
-            &mut self.finalized_chains
+            (&mut self.finalized_chains, true)
         } else {
-            &mut self.head_chains
+            (&mut self.head_chains, false)
         };
         match collection.entry(id) {
             Entry::Occupied(mut entry) => {
@@ -501,6 +501,7 @@ impl<T: BeaconChainTypes, C: BlockStorage> ChainCollection<T, C> {
                     target_head_root,
                     peer,
                     beacon_processor_send.clone(),
+                    is_finalized,
                     &self.log,
                 );
                 debug_assert_eq!(new_chain.get_id(), id);

beacon_node/src/cli.rs

@@ -708,4 +708,12 @@ pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
                 .default_value("250")
                 .takes_value(true)
         )
+        .arg(
+            Arg::with_name("count-unrealized")
+                .long("count-unrealized")
+                .hidden(true)
+                .help("**EXPERIMENTAL** Enables an alternative, potentially more performant FFG \
+                    vote tracking method.")
+                .takes_value(false)
+        )
 }

beacon_node/src/config.rs

@@ -630,6 +630,10 @@ pub fn get_config<E: EthSpec>(
         client_config.chain.fork_choice_before_proposal_timeout_ms = timeout;
     }
 
+    if cli_args.is_present("count-unrealized") {
+        client_config.chain.count_unrealized = true;
+    }
+
     Ok(client_config)
 }
 

beacon_node/store/src/metadata.rs

@@ -4,7 +4,7 @@ use ssz::{Decode, Encode};
 use ssz_derive::{Decode, Encode};
 use types::{Checkpoint, Hash256, Slot};
 
-pub const CURRENT_SCHEMA_VERSION: SchemaVersion = SchemaVersion(9);
+pub const CURRENT_SCHEMA_VERSION: SchemaVersion = SchemaVersion(10);
 
 // All the keys that get stored under the `BeaconMeta` column.
 //

consensus/fork_choice/Cargo.toml

@@ -8,6 +8,7 @@ edition = "2021"
 
 [dependencies]
 types = { path = "../types" }
+state_processing = { path = "../state_processing" }
 proto_array = { path = "../proto_array" }
 eth2_ssz = "0.4.1"
 eth2_ssz_derive = "0.3.0"

consensus/fork_choice/src/fork_choice.rs

@@ -1,6 +1,7 @@
 use crate::{ForkChoiceStore, InvalidationOperation};
 use proto_array::{Block as ProtoBlock, ExecutionStatus, ProtoArrayForkChoice};
 use ssz_derive::{Decode, Encode};
+use state_processing::per_epoch_processing;
 use std::cmp::Ordering;
 use std::marker::PhantomData;
 use std::time::Duration;
@@ -51,6 +52,9 @@ pub enum Error<T> {
     MissingFinalizedBlock {
         finalized_checkpoint: Checkpoint,
     },
+    UnrealizedVoteProcessing(state_processing::EpochProcessingError),
+    ParticipationCacheBuild(BeaconStateError),
+    ValidatorStatuses(BeaconStateError),
 }
 
 impl<T> From<InvalidAttestation> for Error<T> {
@@ -59,6 +63,12 @@ impl<T> From<InvalidAttestation> for Error<T> {
     }
 }
 
+impl<T> From<state_processing::EpochProcessingError> for Error<T> {
+    fn from(e: state_processing::EpochProcessingError) -> Self {
+        Error::UnrealizedVoteProcessing(e)
+    }
+}
+
 #[derive(Debug)]
 pub enum InvalidBlock {
     UnknownParent(Hash256),
@@ -114,6 +124,66 @@ impl<T> From<String> for Error<T> {
     }
 }
 
+/// Indicates whether the unrealized justification of a block should be calculated and tracked.
+/// If a block has been finalized, this can be set to false. This is useful when syncing finalized
+/// portions of the chain. Otherwise this should always be set to true.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum CountUnrealized {
+    True,
+    False,
+}
+
+impl CountUnrealized {
+    pub fn is_true(&self) -> bool {
+        matches!(self, CountUnrealized::True)
+    }
+
+    pub fn and(&self, other: CountUnrealized) -> CountUnrealized {
+        if self.is_true() && other.is_true() {
+            CountUnrealized::True
+        } else {
+            CountUnrealized::False
+        }
+    }
+}
+
+impl From<bool> for CountUnrealized {
+    fn from(count_unrealized: bool) -> Self {
+        if count_unrealized {
+            CountUnrealized::True
+        } else {
+            CountUnrealized::False
+        }
+    }
+}
+
+#[derive(Copy, Clone)]
+enum UpdateJustifiedCheckpointSlots {
+    OnTick {
+        current_slot: Slot,
+    },
+    OnBlock {
+        state_slot: Slot,
+        current_slot: Slot,
+    },
+}
+
+impl UpdateJustifiedCheckpointSlots {
+    fn current_slot(&self) -> Slot {
+        match self {
+            UpdateJustifiedCheckpointSlots::OnTick { current_slot } => *current_slot,
+            UpdateJustifiedCheckpointSlots::OnBlock { current_slot, .. } => *current_slot,
+        }
+    }
+
+    fn state_slot(&self) -> Option<Slot> {
+        match self {
+            UpdateJustifiedCheckpointSlots::OnTick { .. } => None,
+            UpdateJustifiedCheckpointSlots::OnBlock { state_slot, .. } => Some(*state_slot),
+        }
+    }
+}
+
 /// Indicates if a block has been verified by an execution payload.
 ///
 /// There is no variant for "invalid", since such a block should never be added to fork choice.
@@ -162,51 +232,6 @@ fn compute_start_slot_at_epoch<E: EthSpec>(epoch: Epoch) -> Slot {
     epoch.start_slot(E::slots_per_epoch())
 }
 
-/// Called whenever the current time increases.
-///
-/// ## Specification
-///
-/// Equivalent to:
-///
-/// https://github.com/ethereum/eth2.0-specs/blob/v0.12.1/specs/phase0/fork-choice.md#on_tick
-fn on_tick<T, E>(store: &mut T, time: Slot) -> Result<(), Error<T::Error>>
-where
-    T: ForkChoiceStore<E>,
-    E: EthSpec,
-{
-    let previous_slot = store.get_current_slot();
-
-    if time > previous_slot + 1 {
-        return Err(Error::InconsistentOnTick {
-            previous_slot,
-            time,
-        });
-    }
-
-    // Update store time.
-    store.set_current_slot(time);
-
-    let current_slot = store.get_current_slot();
-
-    // Reset proposer boost if this is a new slot.
-    if current_slot > previous_slot {
-        store.set_proposer_boost_root(Hash256::zero());
-    }
-
-    // Not a new epoch, return.
-    if !(current_slot > previous_slot && compute_slots_since_epoch_start::<E>(current_slot) == 0) {
-        return Ok(());
-    }
-
-    if store.best_justified_checkpoint().epoch > store.justified_checkpoint().epoch {
-        store
-            .set_justified_checkpoint(*store.best_justified_checkpoint())
-            .map_err(Error::ForkChoiceStoreError)?;
-    }
-
-    Ok(())
-}
-
 /// Used for queuing attestations from the current slot. Only contains the minimum necessary
 /// information about the attestation.
 #[derive(Clone, PartialEq, Encode, Decode)]
@@ -356,7 +381,7 @@ where
         // If the current slot is not provided, use the value that was last provided to the store.
         let current_slot = current_slot.unwrap_or_else(|| fc_store.get_current_slot());
 
-        let proto_array = ProtoArrayForkChoice::new(
+        let proto_array = ProtoArrayForkChoice::new::<E>(
             finalized_block_slot,
             finalized_block_state_root,
             *fc_store.justified_checkpoint(),
@@ -473,7 +498,7 @@ where
         current_slot: Slot,
         spec: &ChainSpec,
     ) -> Result<Hash256, Error<T::Error>> {
-        self.update_time(current_slot)?;
+        self.update_time(current_slot, spec)?;
 
         let store = &mut self.fc_store;
 
@@ -482,6 +507,7 @@ where
             *store.finalized_checkpoint(),
             store.justified_balances(),
             store.proposer_boost_root(),
+            current_slot,
             spec,
         )?;
 
@@ -539,13 +565,11 @@ where
     /// https://github.com/ethereum/eth2.0-specs/blob/v0.12.1/specs/phase0/fork-choice.md#should_update_justified_checkpoint
     fn should_update_justified_checkpoint(
         &mut self,
-        current_slot: Slot,
+        new_justified_checkpoint: Checkpoint,
-        state: &BeaconState<E>,
+        slots: UpdateJustifiedCheckpointSlots,
         spec: &ChainSpec,
     ) -> Result<bool, Error<T::Error>> {
-        self.update_time(current_slot)?;
+        self.update_time(slots.current_slot(), spec)?;
-
-        let new_justified_checkpoint = &state.current_justified_checkpoint();
 
         if compute_slots_since_epoch_start::<E>(self.fc_store.get_current_slot())
             < spec.safe_slots_to_update_justified
@@ -557,12 +581,14 @@ where
             compute_start_slot_at_epoch::<E>(self.fc_store.justified_checkpoint().epoch);
 
         // This sanity check is not in the spec, but the invariant is implied.
-        if justified_slot >= state.slot() {
+        if let Some(state_slot) = slots.state_slot() {
+            if justified_slot >= state_slot {
                 return Err(Error::AttemptToRevertJustification {
                     store: justified_slot,
-                state: state.slot(),
+                    state: state_slot,
                 });
             }
+        }
 
         // We know that the slot for `new_justified_checkpoint.root` is not greater than
         // `state.slot`, since a state cannot justify its own slot.
@@ -629,15 +655,15 @@ where
         state: &BeaconState<E>,
         payload_verification_status: PayloadVerificationStatus,
         spec: &ChainSpec,
+        count_unrealized: CountUnrealized,
     ) -> Result<(), Error<T::Error>> {
-        let current_slot = self.update_time(current_slot)?;
+        let current_slot = self.update_time(current_slot, spec)?;
 
         // Parent block must be known.
-        if !self.proto_array.contains_block(&block.parent_root()) {
+        let parent_block = self
-            return Err(Error::InvalidBlock(InvalidBlock::UnknownParent(
+            .proto_array
-                block.parent_root(),
+            .get_block(&block.parent_root())
-            )));
+            .ok_or_else(|| Error::InvalidBlock(InvalidBlock::UnknownParent(block.parent_root())))?;
-        }
 
         // Blocks cannot be in the future. If they are, their consideration must be delayed until
         // the are in the past.
@@ -686,30 +712,111 @@ where
             self.fc_store.set_proposer_boost_root(block_root);
         }
 
-        // Update justified checkpoint.
+        let update_justified_checkpoint_slots = UpdateJustifiedCheckpointSlots::OnBlock {
-        if state.current_justified_checkpoint().epoch > self.fc_store.justified_checkpoint().epoch {
+            state_slot: state.slot(),
-            if state.current_justified_checkpoint().epoch
+            current_slot,
-                > self.fc_store.best_justified_checkpoint().epoch
+        };
+
+        // Update store with checkpoints if necessary
+        self.update_checkpoints(
+            state.current_justified_checkpoint(),
+            state.finalized_checkpoint(),
+            update_justified_checkpoint_slots,
+            spec,
+        )?;
+
+        // Update unrealized justified/finalized checkpoints.
+        let (unrealized_justified_checkpoint, unrealized_finalized_checkpoint) = if count_unrealized
+            .is_true()
+        {
+            let block_epoch = block.slot().epoch(E::slots_per_epoch());
+
+            // If the parent checkpoints are already at the same epoch as the block being imported,
+            // it's impossible for the unrealized checkpoints to differ from the parent's. This
+            // holds true because:
+            //
+            // 1. A child block cannot have lower FFG checkpoints than its parent.
+            // 2. A block in epoch `N` cannot contain attestations which would justify an epoch higher than `N`.
+            // 3. A block in epoch `N` cannot contain attestations which would finalize an epoch higher than `N - 1`.
+            //
+            // This is an optimization. It should reduce the amount of times we run
+            // `process_justification_and_finalization` by approximately 1/3rd when the chain is
+            // performing optimally.
+            let parent_checkpoints = parent_block
+                .unrealized_justified_checkpoint
+                .zip(parent_block.unrealized_finalized_checkpoint)
+                .filter(|(parent_justified, parent_finalized)| {
+                    parent_justified.epoch == block_epoch
+                        && parent_finalized.epoch + 1 >= block_epoch
+                });
+
+            let (unrealized_justified_checkpoint, unrealized_finalized_checkpoint) =
+                if let Some((parent_justified, parent_finalized)) = parent_checkpoints {
+                    (parent_justified, parent_finalized)
+                } else {
+                    let justification_and_finalization_state = match block {
+                        BeaconBlockRef::Merge(_) | BeaconBlockRef::Altair(_) => {
+                            let participation_cache =
+                                per_epoch_processing::altair::ParticipationCache::new(state, spec)
+                                    .map_err(Error::ParticipationCacheBuild)?;
+                            per_epoch_processing::altair::process_justification_and_finalization(
+                                state,
+                                &participation_cache,
+                            )?
+                        }
+                        BeaconBlockRef::Base(_) => {
+                            let mut validator_statuses =
+                                per_epoch_processing::base::ValidatorStatuses::new(state, spec)
+                                    .map_err(Error::ValidatorStatuses)?;
+                            validator_statuses
+                                .process_attestations(state)
+                                .map_err(Error::ValidatorStatuses)?;
+                            per_epoch_processing::base::process_justification_and_finalization(
+                                state,
+                                &validator_statuses.total_balances,
+                                spec,
+                            )?
+                        }
+                    };
+
+                    (
+                        justification_and_finalization_state.current_justified_checkpoint(),
+                        justification_and_finalization_state.finalized_checkpoint(),
+                    )
+                };
+
+            // Update best known unrealized justified & finalized checkpoints
+            if unrealized_justified_checkpoint.epoch
+                > self.fc_store.unrealized_justified_checkpoint().epoch
             {
                 self.fc_store
-                    .set_best_justified_checkpoint(state.current_justified_checkpoint());
+                    .set_unrealized_justified_checkpoint(unrealized_justified_checkpoint);
             }
-            if self.should_update_justified_checkpoint(current_slot, state, spec)? {
+            if unrealized_finalized_checkpoint.epoch
+                > self.fc_store.unrealized_finalized_checkpoint().epoch
+            {
                 self.fc_store
-                    .set_justified_checkpoint(state.current_justified_checkpoint())
+                    .set_unrealized_finalized_checkpoint(unrealized_finalized_checkpoint);
-                    .map_err(Error::UnableToSetJustifiedCheckpoint)?;
-            }
             }
 
-        // Update finalized checkpoint.
+            // If block is from past epochs, try to update store's justified & finalized checkpoints right away
-        if state.finalized_checkpoint().epoch > self.fc_store.finalized_checkpoint().epoch {
+            if block.slot().epoch(E::slots_per_epoch()) < current_slot.epoch(E::slots_per_epoch()) {
-            self.fc_store
+                self.update_checkpoints(
-                .set_finalized_checkpoint(state.finalized_checkpoint());
+                    unrealized_justified_checkpoint,
-            self.fc_store
+                    unrealized_finalized_checkpoint,
-                .set_justified_checkpoint(state.current_justified_checkpoint())
+                    update_justified_checkpoint_slots,
-                .map_err(Error::UnableToSetJustifiedCheckpoint)?;
+                    spec,
+                )?;
             }
 
+            (
+                Some(unrealized_justified_checkpoint),
+                Some(unrealized_finalized_checkpoint),
+            )
+        } else {
+            (None, None)
+        };
+
         let target_slot = block
             .slot()
             .epoch(E::slots_per_epoch())
@@ -757,7 +864,8 @@ where
 
         // This does not apply a vote to the block, it just makes fork choice aware of the block so
         // it can still be identified as the head even if it doesn't have any votes.
-        self.proto_array.process_block(ProtoBlock {
+        self.proto_array.process_block::<E>(
+            ProtoBlock {
                 slot: block.slot(),
                 root: block_root,
                 parent_root: Some(block.parent_root()),
@@ -778,11 +886,46 @@ where
                 justified_checkpoint: state.current_justified_checkpoint(),
                 finalized_checkpoint: state.finalized_checkpoint(),
                 execution_status,
-        })?;
+                unrealized_justified_checkpoint,
+                unrealized_finalized_checkpoint,
+            },
+            current_slot,
+        )?;
 
         Ok(())
     }
 
+    /// Update checkpoints in store if necessary
+    fn update_checkpoints(
+        &mut self,
+        justified_checkpoint: Checkpoint,
+        finalized_checkpoint: Checkpoint,
+        slots: UpdateJustifiedCheckpointSlots,
+        spec: &ChainSpec,
+    ) -> Result<(), Error<T::Error>> {
+        // Update justified checkpoint.
+        if justified_checkpoint.epoch > self.fc_store.justified_checkpoint().epoch {
+            if justified_checkpoint.epoch > self.fc_store.best_justified_checkpoint().epoch {
+                self.fc_store
+                    .set_best_justified_checkpoint(justified_checkpoint);
+            }
+            if self.should_update_justified_checkpoint(justified_checkpoint, slots, spec)? {
+                self.fc_store
+                    .set_justified_checkpoint(justified_checkpoint)
+                    .map_err(Error::UnableToSetJustifiedCheckpoint)?;
+            }
+        }
+
+        // Update finalized checkpoint.
+        if finalized_checkpoint.epoch > self.fc_store.finalized_checkpoint().epoch {
+            self.fc_store.set_finalized_checkpoint(finalized_checkpoint);
+            self.fc_store
+                .set_justified_checkpoint(justified_checkpoint)
+                .map_err(Error::UnableToSetJustifiedCheckpoint)?;
+        }
+        Ok(())
+    }
+
     /// Validates the `epoch` against the current time according to the fork choice store.
     ///
     /// ## Specification
@@ -920,9 +1063,10 @@ where
         current_slot: Slot,
         attestation: &IndexedAttestation<E>,
         is_from_block: AttestationFromBlock,
+        spec: &ChainSpec,
     ) -> Result<(), Error<T::Error>> {
         // Ensure the store is up-to-date.
-        self.update_time(current_slot)?;
+        self.update_time(current_slot, spec)?;
 
         // Ignore any attestations to the zero hash.
         //
@@ -967,12 +1111,16 @@ where
 
     /// Call `on_tick` for all slots between `fc_store.get_current_slot()` and the provided
     /// `current_slot`. Returns the value of `self.fc_store.get_current_slot`.
-    pub fn update_time(&mut self, current_slot: Slot) -> Result<Slot, Error<T::Error>> {
+    pub fn update_time(
+        &mut self,
+        current_slot: Slot,
+        spec: &ChainSpec,
+    ) -> Result<Slot, Error<T::Error>> {
         while self.fc_store.get_current_slot() < current_slot {
             let previous_slot = self.fc_store.get_current_slot();
             // Note: we are relying upon `on_tick` to update `fc_store.time` to ensure we don't
             // get stuck in a loop.
-            on_tick(&mut self.fc_store, previous_slot + 1)?
+            self.on_tick(previous_slot + 1, spec)?
         }
 
         // Process any attestations that might now be eligible.
@@ -981,6 +1129,63 @@ where
         Ok(self.fc_store.get_current_slot())
     }
 
+    /// Called whenever the current time increases.
+    ///
+    /// ## Specification
+    ///
+    /// Equivalent to:
+    ///
+    /// https://github.com/ethereum/eth2.0-specs/blob/v0.12.1/specs/phase0/fork-choice.md#on_tick
+    fn on_tick(&mut self, time: Slot, spec: &ChainSpec) -> Result<(), Error<T::Error>> {
+        let store = &mut self.fc_store;
+        let previous_slot = store.get_current_slot();
+
+        if time > previous_slot + 1 {
+            return Err(Error::InconsistentOnTick {
+                previous_slot,
+                time,
+            });
+        }
+
+        // Update store time.
+        store.set_current_slot(time);
+
+        let current_slot = store.get_current_slot();
+
+        // Reset proposer boost if this is a new slot.
+        if current_slot > previous_slot {
+            store.set_proposer_boost_root(Hash256::zero());
+        }
+
+        // Not a new epoch, return.
+        if !(current_slot > previous_slot
+            && compute_slots_since_epoch_start::<E>(current_slot) == 0)
+        {
+            return Ok(());
+        }
+
+        if store.best_justified_checkpoint().epoch > store.justified_checkpoint().epoch {
+            let store = &self.fc_store;
+            if self.is_descendant_of_finalized(store.best_justified_checkpoint().root) {
+                let store = &mut self.fc_store;
+                store
+                    .set_justified_checkpoint(*store.best_justified_checkpoint())
+                    .map_err(Error::ForkChoiceStoreError)?;
+            }
+        }
+
+        // Update store.justified_checkpoint if a better unrealized justified checkpoint is known
+        let unrealized_justified_checkpoint = *self.fc_store.unrealized_justified_checkpoint();
+        let unrealized_finalized_checkpoint = *self.fc_store.unrealized_finalized_checkpoint();
+        self.update_checkpoints(
+            unrealized_justified_checkpoint,
+            unrealized_finalized_checkpoint,
+            UpdateJustifiedCheckpointSlots::OnTick { current_slot },
+            spec,
+        )?;
+        Ok(())
+    }
+
     /// Processes and removes from the queue any queued attestations which may now be eligible for
     /// processing due to the slot clock incrementing.
     fn process_attestation_queue(&mut self) -> Result<(), Error<T::Error>> {
@@ -1158,6 +1363,14 @@ where
         *self.fc_store.best_justified_checkpoint()
     }
 
+    pub fn unrealized_justified_checkpoint(&self) -> Checkpoint {
+        *self.fc_store.unrealized_justified_checkpoint()
+    }
+
+    pub fn unrealized_finalized_checkpoint(&self) -> Checkpoint {
+        *self.fc_store.unrealized_finalized_checkpoint()
+    }
+
     /// Returns the latest message for a given validator, if any.
     ///
     /// Returns `(block_root, block_slot)`.

consensus/fork_choice/src/fork_choice_store.rs

@@ -50,6 +50,12 @@ pub trait ForkChoiceStore<T: EthSpec>: Sized {
     /// Returns the `finalized_checkpoint`.
     fn finalized_checkpoint(&self) -> &Checkpoint;
 
+    /// Returns the `unrealized_justified_checkpoint`.
+    fn unrealized_justified_checkpoint(&self) -> &Checkpoint;
+
+    /// Returns the `unrealized_finalized_checkpoint`.
+    fn unrealized_finalized_checkpoint(&self) -> &Checkpoint;
+
     /// Returns the `proposer_boost_root`.
     fn proposer_boost_root(&self) -> Hash256;
 
@@ -62,6 +68,12 @@ pub trait ForkChoiceStore<T: EthSpec>: Sized {
     /// Sets the `best_justified_checkpoint`.
     fn set_best_justified_checkpoint(&mut self, checkpoint: Checkpoint);
 
+    /// Sets the `unrealized_justified_checkpoint`.
+    fn set_unrealized_justified_checkpoint(&mut self, checkpoint: Checkpoint);
+
+    /// Sets the `unrealized_finalized_checkpoint`.
+    fn set_unrealized_finalized_checkpoint(&mut self, checkpoint: Checkpoint);
+
     /// Sets the proposer boost root.
     fn set_proposer_boost_root(&mut self, proposer_boost_root: Hash256);
 }

consensus/fork_choice/src/lib.rs

@@ -2,9 +2,9 @@ mod fork_choice;
 mod fork_choice_store;
 
 pub use crate::fork_choice::{
-    AttestationFromBlock, Error, ForkChoice, ForkChoiceView, ForkchoiceUpdateParameters,
+    AttestationFromBlock, CountUnrealized, Error, ForkChoice, ForkChoiceView,
-    InvalidAttestation, InvalidBlock, PayloadVerificationStatus, PersistedForkChoice,
+    ForkchoiceUpdateParameters, InvalidAttestation, InvalidBlock, PayloadVerificationStatus,
-    QueuedAttestation,
+    PersistedForkChoice, QueuedAttestation,
 };
 pub use fork_choice_store::ForkChoiceStore;
 pub use proto_array::{Block as ProtoBlock, ExecutionStatus, InvalidationOperation};

consensus/fork_choice/tests/tests.rs

@@ -12,7 +12,8 @@ use beacon_chain::{
     StateSkipConfig, WhenSlotSkipped,
 };
 use fork_choice::{
-    ForkChoiceStore, InvalidAttestation, InvalidBlock, PayloadVerificationStatus, QueuedAttestation,
+    CountUnrealized, ForkChoiceStore, InvalidAttestation, InvalidBlock, PayloadVerificationStatus,
+    QueuedAttestation,
 };
 use store::MemoryStore;
 use types::{
@@ -150,7 +151,7 @@ impl ForkChoiceTest {
             .chain
             .canonical_head
             .fork_choice_write_lock()
-            .update_time(self.harness.chain.slot().unwrap())
+            .update_time(self.harness.chain.slot().unwrap(), &self.harness.spec)
             .unwrap();
         func(
             self.harness
@@ -292,6 +293,7 @@ impl ForkChoiceTest {
                 &state,
                 PayloadVerificationStatus::Verified,
                 &self.harness.chain.spec,
+                CountUnrealized::True,
             )
             .unwrap();
         self
@@ -334,6 +336,7 @@ impl ForkChoiceTest {
                 &state,
                 PayloadVerificationStatus::Verified,
                 &self.harness.chain.spec,
+                CountUnrealized::True,
             )
             .err()
             .expect("on_block did not return an error");

consensus/proto_array/src/fork_choice_test_definition.rs

@@ -78,7 +78,7 @@ impl ForkChoiceTestDefinition {
 
         let junk_shuffling_id =
             AttestationShufflingId::from_components(Epoch::new(0), Hash256::zero());
-        let mut fork_choice = ProtoArrayForkChoice::new(
+        let mut fork_choice = ProtoArrayForkChoice::new::<MainnetEthSpec>(
             self.finalized_block_slot,
             Hash256::zero(),
             self.justified_checkpoint,
@@ -103,6 +103,7 @@ impl ForkChoiceTestDefinition {
                             finalized_checkpoint,
                             &justified_state_balances,
                             Hash256::zero(),
+                            Slot::new(0),
                             &spec,
                         )
                         .unwrap_or_else(|e| {
@@ -129,6 +130,7 @@ impl ForkChoiceTestDefinition {
                             finalized_checkpoint,
                             &justified_state_balances,
                             proposer_boost_root,
+                            Slot::new(0),
                             &spec,
                         )
                         .unwrap_or_else(|e| {
@@ -152,6 +154,7 @@ impl ForkChoiceTestDefinition {
                         finalized_checkpoint,
                         &justified_state_balances,
                         Hash256::zero(),
+                        Slot::new(0),
                         &spec,
                     );
 
@@ -190,8 +193,12 @@ impl ForkChoiceTestDefinition {
                         execution_status: ExecutionStatus::Optimistic(
                             ExecutionBlockHash::from_root(root),
                         ),
+                        unrealized_justified_checkpoint: None,
+                        unrealized_finalized_checkpoint: None,
                     };
-                    fork_choice.process_block(block).unwrap_or_else(|e| {
+                    fork_choice
+                        .process_block::<MainnetEthSpec>(block, slot)
+                        .unwrap_or_else(|e| {
                             panic!(
                                 "process_block op at index {} returned error: {:?}",
                                 op_index, e

consensus/proto_array/src/proto_array.rs

@@ -97,6 +97,10 @@ pub struct ProtoNode {
     /// Indicates if an execution node has marked this block as valid. Also contains the execution
     /// block hash.
     pub execution_status: ExecutionStatus,
+    #[ssz(with = "four_byte_option_checkpoint")]
+    pub unrealized_justified_checkpoint: Option<Checkpoint>,
+    #[ssz(with = "four_byte_option_checkpoint")]
+    pub unrealized_finalized_checkpoint: Option<Checkpoint>,
 }
 
 #[derive(PartialEq, Debug, Encode, Decode, Serialize, Deserialize, Copy, Clone)]
@@ -140,6 +144,7 @@ impl ProtoArray {
     /// - Compare the current node with the parents best-child, updating it if the current node
     /// should become the best child.
     /// - If required, update the parents best-descendant with the current node or its best-descendant.
+    #[allow(clippy::too_many_arguments)]
     pub fn apply_score_changes<E: EthSpec>(
         &mut self,
         mut deltas: Vec<i64>,
@@ -147,6 +152,7 @@ impl ProtoArray {
         finalized_checkpoint: Checkpoint,
         new_balances: &[u64],
         proposer_boost_root: Hash256,
+        current_slot: Slot,
         spec: &ChainSpec,
     ) -> Result<(), Error> {
         if deltas.len() != self.indices.len() {
@@ -280,7 +286,11 @@ impl ProtoArray {
 
             // If the node has a parent, try to update its best-child and best-descendant.
             if let Some(parent_index) = node.parent {
-                self.maybe_update_best_child_and_descendant(parent_index, node_index)?;
+                self.maybe_update_best_child_and_descendant::<E>(
+                    parent_index,
+                    node_index,
+                    current_slot,
+                )?;
             }
         }
 
@@ -290,7 +300,7 @@ impl ProtoArray {
     /// Register a block with the fork choice.
     ///
     /// It is only sane to supply a `None` parent for the genesis block.
-    pub fn on_block(&mut self, block: Block) -> Result<(), Error> {
+    pub fn on_block<E: EthSpec>(&mut self, block: Block, current_slot: Slot) -> Result<(), Error> {
         // If the block is already known, simply ignore it.
         if self.indices.contains_key(&block.root) {
             return Ok(());
@@ -314,6 +324,8 @@ impl ProtoArray {
             best_child: None,
             best_descendant: None,
             execution_status: block.execution_status,
+            unrealized_justified_checkpoint: block.unrealized_justified_checkpoint,
+            unrealized_finalized_checkpoint: block.unrealized_finalized_checkpoint,
         };
 
         // If the parent has an invalid execution status, return an error before adding the block to
@@ -335,7 +347,11 @@ impl ProtoArray {
         self.nodes.push(node.clone());
 
         if let Some(parent_index) = node.parent {
-            self.maybe_update_best_child_and_descendant(parent_index, node_index)?;
+            self.maybe_update_best_child_and_descendant::<E>(
+                parent_index,
+                node_index,
+                current_slot,
+            )?;
 
             if matches!(block.execution_status, ExecutionStatus::Valid(_)) {
                 self.propagate_execution_payload_validation_by_index(parent_index)?;
@@ -604,7 +620,11 @@ impl ProtoArray {
     /// been called without a subsequent `Self::apply_score_changes` call. This is because
     /// `on_new_block` does not attempt to walk backwards through the tree and update the
     /// best-child/best-descendant links.
-    pub fn find_head(&self, justified_root: &Hash256) -> Result<Hash256, Error> {
+    pub fn find_head<E: EthSpec>(
+        &self,
+        justified_root: &Hash256,
+        current_slot: Slot,
+    ) -> Result<Hash256, Error> {
         let justified_index = self
             .indices
             .get(justified_root)
@@ -637,7 +657,7 @@ impl ProtoArray {
             .ok_or(Error::InvalidBestDescendant(best_descendant_index))?;
 
         // Perform a sanity check that the node is indeed valid to be the head.
-        if !self.node_is_viable_for_head(best_node) {
+        if !self.node_is_viable_for_head::<E>(best_node, current_slot) {
             return Err(Error::InvalidBestNode(Box::new(InvalidBestNodeInfo {
                 start_root: *justified_root,
                 justified_checkpoint: self.justified_checkpoint,
@@ -733,10 +753,11 @@ impl ProtoArray {
     ///     best-descendant.
     /// - The child is not the best child but becomes the best child.
     /// - The child is not the best child and does not become the best child.
-    fn maybe_update_best_child_and_descendant(
+    fn maybe_update_best_child_and_descendant<E: EthSpec>(
         &mut self,
         parent_index: usize,
         child_index: usize,
+        current_slot: Slot,
     ) -> Result<(), Error> {
         let child = self
             .nodes
@@ -748,7 +769,8 @@ impl ProtoArray {
             .get(parent_index)
             .ok_or(Error::InvalidNodeIndex(parent_index))?;
 
-        let child_leads_to_viable_head = self.node_leads_to_viable_head(child)?;
+        let child_leads_to_viable_head =
+            self.node_leads_to_viable_head::<E>(child, current_slot)?;
 
         // These three variables are aliases to the three options that we may set the
         // `parent.best_child` and `parent.best_descendant` to.
@@ -761,9 +783,8 @@ impl ProtoArray {
         );
         let no_change = (parent.best_child, parent.best_descendant);
 
-        let (new_best_child, new_best_descendant) = if let Some(best_child_index) =
+        let (new_best_child, new_best_descendant) =
-            parent.best_child
+            if let Some(best_child_index) = parent.best_child {
-        {
                 if best_child_index == child_index && !child_leads_to_viable_head {
                     // If the child is already the best-child of the parent but it's not viable for
                     // the head, remove it.
@@ -778,7 +799,8 @@ impl ProtoArray {
                         .get(best_child_index)
                         .ok_or(Error::InvalidBestDescendant(best_child_index))?;
 
-                let best_child_leads_to_viable_head = self.node_leads_to_viable_head(best_child)?;
+                    let best_child_leads_to_viable_head =
+                        self.node_leads_to_viable_head::<E>(best_child, current_slot)?;
 
                     if child_leads_to_viable_head && !best_child_leads_to_viable_head {
                         // The child leads to a viable head, but the current best-child doesn't.
@@ -823,7 +845,11 @@ impl ProtoArray {
 
     /// Indicates if the node itself is viable for the head, or if it's best descendant is viable
     /// for the head.
-    fn node_leads_to_viable_head(&self, node: &ProtoNode) -> Result<bool, Error> {
+    fn node_leads_to_viable_head<E: EthSpec>(
+        &self,
+        node: &ProtoNode,
+        current_slot: Slot,
+    ) -> Result<bool, Error> {
         let best_descendant_is_viable_for_head =
             if let Some(best_descendant_index) = node.best_descendant {
                 let best_descendant = self
@@ -831,12 +857,13 @@ impl ProtoArray {
                     .get(best_descendant_index)
                     .ok_or(Error::InvalidBestDescendant(best_descendant_index))?;
 
-                self.node_is_viable_for_head(best_descendant)
+                self.node_is_viable_for_head::<E>(best_descendant, current_slot)
             } else {
                 false
             };
 
-        Ok(best_descendant_is_viable_for_head || self.node_is_viable_for_head(node))
+        Ok(best_descendant_is_viable_for_head
+            || self.node_is_viable_for_head::<E>(node, current_slot))
     }
 
     /// This is the equivalent to the `filter_block_tree` function in the eth2 spec:
@@ -845,18 +872,43 @@ impl ProtoArray {
     ///
     /// Any node that has a different finalized or justified epoch should not be viable for the
     /// head.
-    fn node_is_viable_for_head(&self, node: &ProtoNode) -> bool {
+    fn node_is_viable_for_head<E: EthSpec>(&self, node: &ProtoNode, current_slot: Slot) -> bool {
         if node.execution_status.is_invalid() {
             return false;
         }
 
-        if let (Some(node_justified_checkpoint), Some(node_finalized_checkpoint)) =
+        let checkpoint_match_predicate =
+            |node_justified_checkpoint: Checkpoint, node_finalized_checkpoint: Checkpoint| {
+                let correct_justified = node_justified_checkpoint == self.justified_checkpoint
+                    || self.justified_checkpoint.epoch == Epoch::new(0);
+                let correct_finalized = node_finalized_checkpoint == self.finalized_checkpoint
+                    || self.finalized_checkpoint.epoch == Epoch::new(0);
+                correct_justified && correct_finalized
+            };
+
+        if let (
+            Some(unrealized_justified_checkpoint),
+            Some(unrealized_finalized_checkpoint),
+            Some(justified_checkpoint),
+            Some(finalized_checkpoint),
+        ) = (
+            node.unrealized_justified_checkpoint,
+            node.unrealized_finalized_checkpoint,
+            node.justified_checkpoint,
+            node.finalized_checkpoint,
+        ) {
+            if node.slot.epoch(E::slots_per_epoch()) < current_slot.epoch(E::slots_per_epoch()) {
+                checkpoint_match_predicate(
+                    unrealized_justified_checkpoint,
+                    unrealized_finalized_checkpoint,
+                )
+            } else {
+                checkpoint_match_predicate(justified_checkpoint, finalized_checkpoint)
+            }
+        } else if let (Some(justified_checkpoint), Some(finalized_checkpoint)) =
             (node.justified_checkpoint, node.finalized_checkpoint)
         {
-            (node_justified_checkpoint == self.justified_checkpoint
+            checkpoint_match_predicate(justified_checkpoint, finalized_checkpoint)
-                || self.justified_checkpoint.epoch == Epoch::new(0))
-                && (node_finalized_checkpoint == self.finalized_checkpoint
-                    || self.finalized_checkpoint.epoch == Epoch::new(0))
         } else {
             false
         }

consensus/proto_array/src/proto_array_fork_choice.rs

@@ -124,6 +124,8 @@ pub struct Block {
     /// Indicates if an execution node has marked this block as valid. Also contains the execution
     /// block hash.
     pub execution_status: ExecutionStatus,
+    pub unrealized_justified_checkpoint: Option<Checkpoint>,
+    pub unrealized_finalized_checkpoint: Option<Checkpoint>,
 }
 
 /// A Vec-wrapper which will grow to match any request.
@@ -162,7 +164,7 @@ pub struct ProtoArrayForkChoice {
 
 impl ProtoArrayForkChoice {
     #[allow(clippy::too_many_arguments)]
-    pub fn new(
+    pub fn new<E: EthSpec>(
         finalized_block_slot: Slot,
         finalized_block_state_root: Hash256,
         justified_checkpoint: Checkpoint,
@@ -193,10 +195,12 @@ impl ProtoArrayForkChoice {
             justified_checkpoint,
             finalized_checkpoint,
             execution_status,
+            unrealized_justified_checkpoint: Some(justified_checkpoint),
+            unrealized_finalized_checkpoint: Some(finalized_checkpoint),
         };
 
         proto_array
-            .on_block(block)
+            .on_block::<E>(block, finalized_block_slot)
             .map_err(|e| format!("Failed to add finalized block to proto_array: {:?}", e))?;
 
         Ok(Self {
@@ -242,13 +246,17 @@ impl ProtoArrayForkChoice {
         Ok(())
     }
 
-    pub fn process_block(&mut self, block: Block) -> Result<(), String> {
+    pub fn process_block<E: EthSpec>(
+        &mut self,
+        block: Block,
+        current_slot: Slot,
+    ) -> Result<(), String> {
         if block.parent_root.is_none() {
             return Err("Missing parent root".to_string());
         }
 
         self.proto_array
-            .on_block(block)
+            .on_block::<E>(block, current_slot)
             .map_err(|e| format!("process_block_error: {:?}", e))
     }
 
@@ -258,6 +266,7 @@ impl ProtoArrayForkChoice {
         finalized_checkpoint: Checkpoint,
         justified_state_balances: &[u64],
         proposer_boost_root: Hash256,
+        current_slot: Slot,
         spec: &ChainSpec,
     ) -> Result<Hash256, String> {
         let old_balances = &mut self.balances;
@@ -279,6 +288,7 @@ impl ProtoArrayForkChoice {
                 finalized_checkpoint,
                 new_balances,
                 proposer_boost_root,
+                current_slot,
                 spec,
             )
             .map_err(|e| format!("find_head apply_score_changes failed: {:?}", e))?;
@@ -286,7 +296,7 @@ impl ProtoArrayForkChoice {
         *old_balances = new_balances.to_vec();
 
         self.proto_array
-            .find_head(&justified_checkpoint.root)
+            .find_head::<E>(&justified_checkpoint.root, current_slot)
             .map_err(|e| format!("find_head failed: {:?}", e))
     }
 
@@ -341,6 +351,8 @@ impl ProtoArrayForkChoice {
                 justified_checkpoint,
                 finalized_checkpoint,
                 execution_status: block.execution_status,
+                unrealized_justified_checkpoint: block.unrealized_justified_checkpoint,
+                unrealized_finalized_checkpoint: block.unrealized_finalized_checkpoint,
             })
         } else {
             None
@@ -485,6 +497,7 @@ fn compute_deltas(
 #[cfg(test)]
 mod test_compute_deltas {
     use super::*;
+    use types::MainnetEthSpec;
 
     /// Gives a hash that is not the zero hash (unless i is `usize::max_value)`.
     fn hash_from_index(i: usize) -> Hash256 {
@@ -510,7 +523,7 @@ mod test_compute_deltas {
             root: finalized_root,
         };
 
-        let mut fc = ProtoArrayForkChoice::new(
+        let mut fc = ProtoArrayForkChoice::new::<MainnetEthSpec>(
             genesis_slot,
             state_root,
             genesis_checkpoint,
@@ -523,7 +536,8 @@ mod test_compute_deltas {
 
         // Add block that is a finalized descendant.
         fc.proto_array
-            .on_block(Block {
+            .on_block::<MainnetEthSpec>(
+                Block {
                     slot: genesis_slot + 1,
                     root: finalized_desc,
                     parent_root: Some(finalized_root),
@@ -534,12 +548,17 @@ mod test_compute_deltas {
                     justified_checkpoint: genesis_checkpoint,
                     finalized_checkpoint: genesis_checkpoint,
                     execution_status,
-            })
+                    unrealized_justified_checkpoint: Some(genesis_checkpoint),
+                    unrealized_finalized_checkpoint: Some(genesis_checkpoint),
+                },
+                genesis_slot + 1,
+            )
             .unwrap();
 
         // Add block that is *not* a finalized descendant.
         fc.proto_array
-            .on_block(Block {
+            .on_block::<MainnetEthSpec>(
+                Block {
                     slot: genesis_slot + 1,
                     root: not_finalized_desc,
                     parent_root: None,
@@ -550,7 +569,11 @@ mod test_compute_deltas {
                     justified_checkpoint: genesis_checkpoint,
                     finalized_checkpoint: genesis_checkpoint,
                     execution_status,
-            })
+                    unrealized_justified_checkpoint: None,
+                    unrealized_finalized_checkpoint: None,
+                },
+                genesis_slot + 1,
+            )
             .unwrap();
 
         assert!(!fc.is_descendant(unknown, unknown));

consensus/state_processing/src/per_epoch_processing.rs

@@ -2,6 +2,7 @@
 
 pub use epoch_processing_summary::EpochProcessingSummary;
 use errors::EpochProcessingError as Error;
+pub use justification_and_finalization_state::JustificationAndFinalizationState;
 pub use registry_updates::process_registry_updates;
 use safe_arith::SafeArith;
 pub use slashings::process_slashings;
@@ -14,6 +15,7 @@ pub mod effective_balance_updates;
 pub mod epoch_processing_summary;
 pub mod errors;
 pub mod historical_roots_update;
+pub mod justification_and_finalization_state;
 pub mod registry_updates;
 pub mod resets;
 pub mod slashings;

consensus/state_processing/src/per_epoch_processing/altair.rs

@@ -33,7 +33,9 @@ pub fn process_epoch<T: EthSpec>(
     let sync_committee = state.current_sync_committee()?.clone();
 
     // Justification and finalization.
+    let justification_and_finalization_state =
         process_justification_and_finalization(state, &participation_cache)?;
+    justification_and_finalization_state.apply_changes_to_state(state);
 
     process_inactivity_updates(state, &participation_cache, spec)?;
 

consensus/state_processing/src/per_epoch_processing/altair/justification_and_finalization.rs

@@ -1,17 +1,21 @@
 use super::ParticipationCache;
-use crate::per_epoch_processing::weigh_justification_and_finalization;
 use crate::per_epoch_processing::Error;
+use crate::per_epoch_processing::{
+    weigh_justification_and_finalization, JustificationAndFinalizationState,
+};
 use safe_arith::SafeArith;
 use types::consts::altair::TIMELY_TARGET_FLAG_INDEX;
 use types::{BeaconState, EthSpec};
 
 /// Update the justified and finalized checkpoints for matching target attestations.
 pub fn process_justification_and_finalization<T: EthSpec>(
-    state: &mut BeaconState<T>,
+    state: &BeaconState<T>,
     participation_cache: &ParticipationCache,
-) -> Result<(), Error> {
+) -> Result<JustificationAndFinalizationState<T>, Error> {
+    let justification_and_finalization_state = JustificationAndFinalizationState::new(state);
+
     if state.current_epoch() <= T::genesis_epoch().safe_add(1)? {
-        return Ok(());
+        return Ok(justification_and_finalization_state);
     }
 
     let previous_epoch = state.previous_epoch();
@@ -24,7 +28,7 @@ pub fn process_justification_and_finalization<T: EthSpec>(
     let previous_target_balance = previous_indices.total_balance()?;
     let current_target_balance = current_indices.total_balance()?;
     weigh_justification_and_finalization(
-        state,
+        justification_and_finalization_state,
         total_active_balance,
         previous_target_balance,
         current_target_balance,

consensus/state_processing/src/per_epoch_processing/base.rs

@@ -31,7 +31,9 @@ pub fn process_epoch<T: EthSpec>(
     validator_statuses.process_attestations(state)?;
 
     // Justification and finalization.
+    let justification_and_finalization_state =
         process_justification_and_finalization(state, &validator_statuses.total_balances, spec)?;
+    justification_and_finalization_state.apply_changes_to_state(state);
 
     // Rewards and Penalties.
     process_rewards_and_penalties(state, &mut validator_statuses, spec)?;

consensus/state_processing/src/per_epoch_processing/base/justification_and_finalization.rs

@@ -1,21 +1,25 @@
 use crate::per_epoch_processing::base::TotalBalances;
-use crate::per_epoch_processing::weigh_justification_and_finalization;
 use crate::per_epoch_processing::Error;
+use crate::per_epoch_processing::{
+    weigh_justification_and_finalization, JustificationAndFinalizationState,
+};
 use safe_arith::SafeArith;
 use types::{BeaconState, ChainSpec, EthSpec};
 
 /// Update the justified and finalized checkpoints for matching target attestations.
 pub fn process_justification_and_finalization<T: EthSpec>(
-    state: &mut BeaconState<T>,
+    state: &BeaconState<T>,
     total_balances: &TotalBalances,
     _spec: &ChainSpec,
-) -> Result<(), Error> {
+) -> Result<JustificationAndFinalizationState<T>, Error> {
+    let justification_and_finalization_state = JustificationAndFinalizationState::new(state);
+
     if state.current_epoch() <= T::genesis_epoch().safe_add(1)? {
-        return Ok(());
+        return Ok(justification_and_finalization_state);
     }
 
     weigh_justification_and_finalization(
-        state,
+        justification_and_finalization_state,
         total_balances.current_epoch(),
         total_balances.previous_epoch_target_attesters(),
         total_balances.current_epoch_target_attesters(),

consensus/state_processing/src/per_epoch_processing/justification_and_finalization_state.rs

@@ -0,0 +1,115 @@
+use types::{BeaconState, BeaconStateError, BitVector, Checkpoint, Epoch, EthSpec, Hash256};
+
+/// This is a subset of the `BeaconState` which is used to compute justification and finality
+/// without modifying the `BeaconState`.
+///
+/// A `JustificationAndFinalizationState` can be created from a `BeaconState` to compute
+/// justification/finality changes and then applied to a `BeaconState` to enshrine those changes.
+#[must_use = "this value must be applied to a state or explicitly dropped"]
+pub struct JustificationAndFinalizationState<T: EthSpec> {
+    /*
+     * Immutable fields.
+     */
+    previous_epoch: Epoch,
+    previous_epoch_target_root: Result<Hash256, BeaconStateError>,
+    current_epoch: Epoch,
+    current_epoch_target_root: Result<Hash256, BeaconStateError>,
+    /*
+     * Mutable fields.
+     */
+    previous_justified_checkpoint: Checkpoint,
+    current_justified_checkpoint: Checkpoint,
+    finalized_checkpoint: Checkpoint,
+    justification_bits: BitVector<T::JustificationBitsLength>,
+}
+
+impl<T: EthSpec> JustificationAndFinalizationState<T> {
+    pub fn new(state: &BeaconState<T>) -> Self {
+        let previous_epoch = state.previous_epoch();
+        let current_epoch = state.current_epoch();
+        Self {
+            previous_epoch,
+            previous_epoch_target_root: state.get_block_root_at_epoch(previous_epoch).copied(),
+            current_epoch,
+            current_epoch_target_root: state.get_block_root_at_epoch(current_epoch).copied(),
+            previous_justified_checkpoint: state.previous_justified_checkpoint(),
+            current_justified_checkpoint: state.current_justified_checkpoint(),
+            finalized_checkpoint: state.finalized_checkpoint(),
+            justification_bits: state.justification_bits().clone(),
+        }
+    }
+
+    pub fn apply_changes_to_state(self, state: &mut BeaconState<T>) {
+        let Self {
+            /*
+             * Immutable fields do not need to be used.
+             */
+            previous_epoch: _,
+            previous_epoch_target_root: _,
+            current_epoch: _,
+            current_epoch_target_root: _,
+            /*
+             * Mutable fields *must* be used.
+             */
+            previous_justified_checkpoint,
+            current_justified_checkpoint,
+            finalized_checkpoint,
+            justification_bits,
+        } = self;
+
+        *state.previous_justified_checkpoint_mut() = previous_justified_checkpoint;
+        *state.current_justified_checkpoint_mut() = current_justified_checkpoint;
+        *state.finalized_checkpoint_mut() = finalized_checkpoint;
+        *state.justification_bits_mut() = justification_bits;
+    }
+
+    pub fn previous_epoch(&self) -> Epoch {
+        self.previous_epoch
+    }
+
+    pub fn current_epoch(&self) -> Epoch {
+        self.current_epoch
+    }
+
+    pub fn get_block_root_at_epoch(&self, epoch: Epoch) -> Result<Hash256, BeaconStateError> {
+        if epoch == self.previous_epoch {
+            self.previous_epoch_target_root.clone()
+        } else if epoch == self.current_epoch {
+            self.current_epoch_target_root.clone()
+        } else {
+            Err(BeaconStateError::SlotOutOfBounds)
+        }
+    }
+
+    pub fn previous_justified_checkpoint(&self) -> Checkpoint {
+        self.previous_justified_checkpoint
+    }
+
+    pub fn previous_justified_checkpoint_mut(&mut self) -> &mut Checkpoint {
+        &mut self.previous_justified_checkpoint
+    }
+
+    pub fn current_justified_checkpoint_mut(&mut self) -> &mut Checkpoint {
+        &mut self.current_justified_checkpoint
+    }
+
+    pub fn current_justified_checkpoint(&self) -> Checkpoint {
+        self.current_justified_checkpoint
+    }
+
+    pub fn finalized_checkpoint(&self) -> Checkpoint {
+        self.finalized_checkpoint
+    }
+
+    pub fn finalized_checkpoint_mut(&mut self) -> &mut Checkpoint {
+        &mut self.finalized_checkpoint
+    }
+
+    pub fn justification_bits(&self) -> &BitVector<T::JustificationBitsLength> {
+        &self.justification_bits
+    }
+
+    pub fn justification_bits_mut(&mut self) -> &mut BitVector<T::JustificationBitsLength> {
+        &mut self.justification_bits
+    }
+}

consensus/state_processing/src/per_epoch_processing/weigh_justification_and_finalization.rs

@@ -1,16 +1,16 @@
-use crate::per_epoch_processing::Error;
+use crate::per_epoch_processing::{Error, JustificationAndFinalizationState};
 use safe_arith::SafeArith;
 use std::ops::Range;
-use types::{BeaconState, Checkpoint, EthSpec};
+use types::{Checkpoint, EthSpec};
 
 /// Update the justified and finalized checkpoints for matching target attestations.
 #[allow(clippy::if_same_then_else)] // For readability and consistency with spec.
 pub fn weigh_justification_and_finalization<T: EthSpec>(
-    state: &mut BeaconState<T>,
+    mut state: JustificationAndFinalizationState<T>,
     total_active_balance: u64,
     previous_target_balance: u64,
     current_target_balance: u64,
-) -> Result<(), Error> {
+) -> Result<JustificationAndFinalizationState<T>, Error> {
     let previous_epoch = state.previous_epoch();
     let current_epoch = state.current_epoch();
 
@@ -24,7 +24,7 @@ pub fn weigh_justification_and_finalization<T: EthSpec>(
     if previous_target_balance.safe_mul(3)? >= total_active_balance.safe_mul(2)? {
         *state.current_justified_checkpoint_mut() = Checkpoint {
             epoch: previous_epoch,
-            root: *state.get_block_root_at_epoch(previous_epoch)?,
+            root: state.get_block_root_at_epoch(previous_epoch)?,
         };
         state.justification_bits_mut().set(1, true)?;
     }
@@ -32,7 +32,7 @@ pub fn weigh_justification_and_finalization<T: EthSpec>(
     if current_target_balance.safe_mul(3)? >= total_active_balance.safe_mul(2)? {
         *state.current_justified_checkpoint_mut() = Checkpoint {
             epoch: current_epoch,
-            root: *state.get_block_root_at_epoch(current_epoch)?,
+            root: state.get_block_root_at_epoch(current_epoch)?,
         };
         state.justification_bits_mut().set(0, true)?;
     }
@@ -66,5 +66,5 @@ pub fn weigh_justification_and_finalization<T: EthSpec>(
         *state.finalized_checkpoint_mut() = old_current_justified_checkpoint;
     }
 
-    Ok(())
+    Ok(state)
 }

consensus/types/src/test_utils/test_random.rs

@@ -129,6 +129,7 @@ macro_rules! impl_test_random_for_u8_array {
     };
 }
 
+impl_test_random_for_u8_array!(3);
 impl_test_random_for_u8_array!(4);
 impl_test_random_for_u8_array!(32);
 impl_test_random_for_u8_array!(48);

lcli/Cargo.toml

@@ -37,3 +37,4 @@ web3 = { version = "0.18.0", default-features = false, features = ["http-tls", "
 eth1_test_rig = { path = "../testing/eth1_test_rig" }
 sensitive_url = { path = "../common/sensitive_url" }
 eth2 = { path = "../common/eth2" }
+snap = "1.0.1"

lcli/src/parse_ssz.rs

@@ -1,7 +1,9 @@
 use clap::ArgMatches;
 use clap_utils::parse_required;
 use serde::Serialize;
+use snap::raw::Decoder;
 use ssz::Decode;
+use std::fs;
 use std::fs::File;
 use std::io::Read;
 use std::str::FromStr;
@@ -29,11 +31,18 @@ pub fn run_parse_ssz<T: EthSpec>(matches: &ArgMatches) -> Result<(), String> {
     let filename = matches.value_of("ssz-file").ok_or("No file supplied")?;
     let format = parse_required(matches, "format")?;
 
+    let bytes = if filename.ends_with("ssz_snappy") {
+        let bytes = fs::read(filename).unwrap();
+        let mut decoder = Decoder::new();
+        decoder.decompress_vec(&bytes).unwrap()
+    } else {
         let mut bytes = vec![];
         let mut file =
             File::open(filename).map_err(|e| format!("Unable to open {}: {}", filename, e))?;
         file.read_to_end(&mut bytes)
             .map_err(|e| format!("Unable to read {}: {}", filename, e))?;
+        bytes
+    };
 
     info!("Using {} spec", T::spec_name());
     info!("Type: {:?}", type_str);

testing/ef_tests/src/cases/epoch_processing.rs

@@ -88,17 +88,23 @@ impl<E: EthSpec> EpochTransition<E> for JustificationAndFinalization {
             BeaconState::Base(_) => {
                 let mut validator_statuses = base::ValidatorStatuses::new(state, spec)?;
                 validator_statuses.process_attestations(state)?;
+                let justification_and_finalization_state =
                     base::process_justification_and_finalization(
                         state,
                         &validator_statuses.total_balances,
                         spec,
-                )
+                    )?;
+                justification_and_finalization_state.apply_changes_to_state(state);
+                Ok(())
             }
             BeaconState::Altair(_) | BeaconState::Merge(_) => {
+                let justification_and_finalization_state =
                     altair::process_justification_and_finalization(
                         state,
                         &altair::ParticipationCache::new(state, spec).unwrap(),
-                )
+                    )?;
+                justification_and_finalization_state.apply_changes_to_state(state);
+                Ok(())
             }
         }
     }

testing/ef_tests/src/cases/fork_choice.rs

@@ -7,7 +7,7 @@ use beacon_chain::{
         obtain_indexed_attestation_and_committees_per_slot, VerifiedAttestation,
     },
     test_utils::{BeaconChainHarness, EphemeralHarnessType},
-    BeaconChainTypes, CachedHead,
+    BeaconChainTypes, CachedHead, CountUnrealized,
 };
 use serde_derive::Deserialize;
 use ssz_derive::Decode;
@@ -16,8 +16,8 @@ use std::future::Future;
 use std::sync::Arc;
 use std::time::Duration;
 use types::{
-    Attestation, BeaconBlock, BeaconState, Checkpoint, EthSpec, ExecutionBlockHash, ForkName,
+    Attestation, AttesterSlashing, BeaconBlock, BeaconState, Checkpoint, EthSpec,
-    Hash256, IndexedAttestation, SignedBeaconBlock, Slot, Uint256,
+    ExecutionBlockHash, ForkName, Hash256, IndexedAttestation, SignedBeaconBlock, Slot, Uint256,
 };
 
 #[derive(Default, Debug, PartialEq, Clone, Deserialize, Decode)]
@@ -45,17 +45,20 @@ pub struct Checks {
     justified_checkpoint_root: Option<Hash256>,
     finalized_checkpoint: Option<Checkpoint>,
     best_justified_checkpoint: Option<Checkpoint>,
+    u_justified_checkpoint: Option<Checkpoint>,
+    u_finalized_checkpoint: Option<Checkpoint>,
     proposer_boost_root: Option<Hash256>,
 }
 
 #[derive(Debug, Clone, Deserialize)]
 #[serde(untagged, deny_unknown_fields)]
-pub enum Step<B, A, P> {
+pub enum Step<B, A, P, S> {
     Tick { tick: u64 },
     ValidBlock { block: B },
     MaybeValidBlock { block: B, valid: bool },
     Attestation { attestation: A },
     PowBlock { pow_block: P },
+    AttesterSlashing { attester_slashing: S },
     Checks { checks: Box<Checks> },
 }
 
@@ -71,16 +74,13 @@ pub struct ForkChoiceTest<E: EthSpec> {
     pub description: String,
     pub anchor_state: BeaconState<E>,
     pub anchor_block: BeaconBlock<E>,
-    pub steps: Vec<Step<SignedBeaconBlock<E>, Attestation<E>, PowBlock>>,
+    #[allow(clippy::type_complexity)]
+    pub steps: Vec<Step<SignedBeaconBlock<E>, Attestation<E>, PowBlock, AttesterSlashing<E>>>,
 }
 
-/// Spec for fork choice tests, with proposer boosting enabled.
+/// Spec to be used for fork choice tests.
-///
-/// This function can be deleted once `ChainSpec::mainnet` enables proposer boosting by default.
 pub fn fork_choice_spec<E: EthSpec>(fork_name: ForkName) -> ChainSpec {
-    let mut spec = testing_spec::<E>(fork_name);
+    testing_spec::<E>(fork_name)
-    spec.proposer_score_boost = Some(70);
-    spec
 }
 
 impl<E: EthSpec> LoadCase for ForkChoiceTest<E> {
@@ -93,7 +93,8 @@ impl<E: EthSpec> LoadCase for ForkChoiceTest<E> {
             .expect("path must be valid OsStr")
             .to_string();
         let spec = &fork_choice_spec::<E>(fork_name);
-        let steps: Vec<Step<String, String, String>> = yaml_decode_file(&path.join("steps.yaml"))?;
+        let steps: Vec<Step<String, String, String, String>> =
+            yaml_decode_file(&path.join("steps.yaml"))?;
         // Resolve the object names in `steps.yaml` into actual decoded block/attestation objects.
         let steps = steps
             .into_iter()
@@ -119,6 +120,10 @@ impl<E: EthSpec> LoadCase for ForkChoiceTest<E> {
                     ssz_decode_file(&path.join(format!("{}.ssz_snappy", pow_block)))
                         .map(|pow_block| Step::PowBlock { pow_block })
                 }
+                Step::AttesterSlashing { attester_slashing } => {
+                    ssz_decode_file(&path.join(format!("{}.ssz_snappy", attester_slashing)))
+                        .map(|attester_slashing| Step::AttesterSlashing { attester_slashing })
+                }
                 Step::Checks { checks } => Ok(Step::Checks { checks }),
             })
             .collect::<Result<_, _>>()?;
@@ -159,7 +164,10 @@ impl<E: EthSpec> Case for ForkChoiceTest<E> {
         // TODO(merge): re-enable this test before production.
         // This test is skipped until we can do retrospective confirmations of the terminal
         // block after an optimistic sync.
-        if self.description == "block_lookup_failed" {
+        if self.description == "block_lookup_failed"
+            //TODO(sean): enable once we implement equivocation logic (https://github.com/sigp/lighthouse/issues/3241)
+            || self.description == "discard_equivocations"
+        {
             return Err(Error::SkippedKnownFailure);
         };
 
@@ -172,6 +180,10 @@ impl<E: EthSpec> Case for ForkChoiceTest<E> {
                 }
                 Step::Attestation { attestation } => tester.process_attestation(attestation)?,
                 Step::PowBlock { pow_block } => tester.process_pow_block(pow_block),
+                //TODO(sean): enable once we implement equivocation logic (https://github.com/sigp/lighthouse/issues/3241)
+                Step::AttesterSlashing {
+                    attester_slashing: _,
+                } => (),
                 Step::Checks { checks } => {
                     let Checks {
                         head,
@@ -181,6 +193,8 @@ impl<E: EthSpec> Case for ForkChoiceTest<E> {
                         justified_checkpoint_root,
                         finalized_checkpoint,
                         best_justified_checkpoint,
+                        u_justified_checkpoint,
+                        u_finalized_checkpoint,
                         proposer_boost_root,
                     } = checks.as_ref();
 
@@ -214,6 +228,14 @@ impl<E: EthSpec> Case for ForkChoiceTest<E> {
                             .check_best_justified_checkpoint(*expected_best_justified_checkpoint)?;
                     }
 
+                    if let Some(expected_u_justified_checkpoint) = u_justified_checkpoint {
+                        tester.check_u_justified_checkpoint(*expected_u_justified_checkpoint)?;
+                    }
+
+                    if let Some(expected_u_finalized_checkpoint) = u_finalized_checkpoint {
+                        tester.check_u_finalized_checkpoint(*expected_u_finalized_checkpoint)?;
+                    }
+
                     if let Some(expected_proposer_boost_root) = proposer_boost_root {
                         tester.check_expected_proposer_boost_root(*expected_proposer_boost_root)?;
                     }
@@ -319,14 +341,18 @@ impl<E: EthSpec> Tester<E> {
             .chain
             .canonical_head
             .fork_choice_write_lock()
-            .update_time(slot)
+            .update_time(slot, &self.spec)
             .unwrap();
     }
 
     pub fn process_block(&self, block: SignedBeaconBlock<E>, valid: bool) -> Result<(), Error> {
         let block_root = block.canonical_root();
         let block = Arc::new(block);
-        let result = self.block_on_dangerous(self.harness.chain.process_block(block.clone()))?;
+        let result = self.block_on_dangerous(
+            self.harness
+                .chain
+                .process_block(block.clone(), CountUnrealized::True),
+        )?;
         if result.is_ok() != valid {
             return Err(Error::DidntFail(format!(
                 "block with root {} was valid={} whilst test expects valid={}. result: {:?}",
@@ -384,6 +410,7 @@ impl<E: EthSpec> Tester<E> {
                         &state,
                         PayloadVerificationStatus::Irrelevant,
                         &self.harness.chain.spec,
+                        self.harness.chain.config.count_unrealized.into(),
                     );
 
                 if result.is_ok() {
@@ -520,6 +547,40 @@ impl<E: EthSpec> Tester<E> {
         )
     }
 
+    pub fn check_u_justified_checkpoint(
+        &self,
+        expected_checkpoint: Checkpoint,
+    ) -> Result<(), Error> {
+        let u_justified_checkpoint = self
+            .harness
+            .chain
+            .canonical_head
+            .fork_choice_read_lock()
+            .unrealized_justified_checkpoint();
+        check_equal(
+            "u_justified_checkpoint",
+            u_justified_checkpoint,
+            expected_checkpoint,
+        )
+    }
+
+    pub fn check_u_finalized_checkpoint(
+        &self,
+        expected_checkpoint: Checkpoint,
+    ) -> Result<(), Error> {
+        let u_finalized_checkpoint = self
+            .harness
+            .chain
+            .canonical_head
+            .fork_choice_read_lock()
+            .unrealized_finalized_checkpoint();
+        check_equal(
+            "u_finalized_checkpoint",
+            u_finalized_checkpoint,
+            expected_checkpoint,
+        )
+    }
+
     pub fn check_expected_proposer_boost_root(
         &self,
         expected_proposer_boost_root: Hash256,