resolve merge conflict and migrate il service to new pardigmn

consensus/proto_array/src/proto_array.rs

@@ -6,11 +6,11 @@ use ssz::Encode;
 use ssz_derive::{Decode, Encode};
 use std::collections::{HashMap, HashSet};
 use superstruct::superstruct;
+use tracing::info;
 use types::{
     AttestationShufflingId, ChainSpec, Checkpoint, Epoch, EthSpec, ExecutionBlockHash,
     FixedBytesExtended, Hash256, Slot,
 };
-use tracing::info;
 
 // Define a "legacy" implementation of `Option<usize>` which uses four bytes for encoding the union
 // selector.
@@ -1075,6 +1075,21 @@ impl ProtoArray {
             })
             .map(|node| node.root)
     }
+
+    /// Returns all nodes that have zero children and are descended from the finalized checkpoint.
+    ///
+    /// For informational purposes like the beacon HTTP API, we use this as the list of known heads,
+    /// even though some of them might not be viable. We do this to maintain consistency between the
+    /// definition of "head" used by pruning (which does not consider viability) and fork choice.
+    pub fn heads_descended_from_finalization<E: EthSpec>(&self) -> Vec<&ProtoNode> {
+        self.nodes
+            .iter()
+            .filter(|node| {
+                node.best_child.is_none()
+                    && self.is_finalized_checkpoint_or_descendant::<E>(node.root)
+            })
+            .collect()
+    }
 }
 
 /// A helper method to calculate the proposer boost based on the given `justified_balances`.