From 3b8a584c550fc7788806e04e7a7e76a9dfb07796 Mon Sep 17 00:00:00 2001
From: Grant Wuerker <gwuerker@gmail.com>
Date: Sun, 21 Jul 2019 22:53:39 +0200
Subject: [PATCH] Expanded fork choice api to provide latest validator message.

---
 eth2/lmd_ghost/src/lib.rs          |  3 +++
 eth2/lmd_ghost/src/reduced_tree.rs | 13 +++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/eth2/lmd_ghost/src/lib.rs b/eth2/lmd_ghost/src/lib.rs
index dd413e2eb..f18b5b81f 100644
--- a/eth2/lmd_ghost/src/lib.rs
+++ b/eth2/lmd_ghost/src/lib.rs
@@ -43,4 +43,7 @@ pub trait LmdGhost<S: Store, E: EthSpec>: Send + Sync {
         finalized_block: &BeaconBlock,
         finalized_block_root: Hash256,
     ) -> Result<()>;
+
+    /// Returns the latest message for a given validator index.
+    fn latest_message(&mut self, validator_index: usize) -> Option<(Hash256, Slot)>;
 }
diff --git a/eth2/lmd_ghost/src/reduced_tree.rs b/eth2/lmd_ghost/src/reduced_tree.rs
index dace2bda6..f069ae68c 100644
--- a/eth2/lmd_ghost/src/reduced_tree.rs
+++ b/eth2/lmd_ghost/src/reduced_tree.rs
@@ -87,6 +87,12 @@ where
             .update_root(new_block.slot, new_root)
             .map_err(|e| format!("update_finalized_root failed: {:?}", e))
     }
+
+    fn latest_message(&mut self, validator_index: usize) -> Option<(Hash256, Slot)> {
+        self.core
+            .write()
+            .latest_message(validator_index)
+    }
 }
 
 struct ReducedTree<T, E> {
@@ -222,6 +228,13 @@ where
         Ok(head_node.block_hash)
     }
 
+    pub fn latest_message(&mut self, validator_index: usize) -> Option<(Hash256, Slot)> {
+        match self.latest_votes.get(validator_index) {
+            Some(v) => Some((v.hash.clone(), v.slot.clone())),
+            None => None
+        }
+    }
+
     fn find_head_from<'a>(&'a self, start_node: &'a Node) -> Result<&'a Node> {
         if start_node.does_not_have_children() {
             Ok(start_node)