Add chain.justified_head

beacon_node/beacon_chain/src/info.rs

@@ -44,4 +44,12 @@ where
         let state = self.state(present_slot).ok()?;
         state.get_beacon_proposer_index(slot, &self.spec)
     }
+
+    pub fn justified_slot(&self) -> u64 {
+        self.justified_head
+            .read()
+            .expect("Justified head poisoned")
+            .beacon_block
+            .slot
+    }
 }

beacon_node/beacon_chain/src/lib.rs

@@ -74,6 +74,7 @@ pub struct BeaconChain<T: ClientDB + Sized, U: SlotClock> {
     pub block_graph: BlockGraph,
     canonical_head: RwLock<CheckPoint>,
     finalized_head: RwLock<CheckPoint>,
+    justified_head: RwLock<CheckPoint>,
     pub latest_attestation_targets: RwLock<AttestationTargets>,
     pub spec: ChainSpec,
 }
@@ -110,6 +111,12 @@ where
             genesis_state.clone(),
             state_root.clone(),
         ));
+        let justified_head = RwLock::new(CheckPoint::new(
+            genesis_block.clone(),
+            block_root.clone(),
+            genesis_state.clone(),
+            state_root.clone(),
+        ));
         let canonical_head = RwLock::new(CheckPoint::new(
             genesis_block.clone(),
             block_root.clone(),
@@ -124,6 +131,7 @@ where
             state_store,
             slot_clock,
             block_graph,
+            justified_head,
             finalized_head,
             canonical_head,
             latest_attestation_targets,