From 4dd1239b243b467cc61bfec282ecae696f082270 Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Sun, 28 Apr 2019 11:33:48 +1000
Subject: [PATCH] Add caching to state transition

---
 eth2/state_processing/src/per_slot_processing.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/eth2/state_processing/src/per_slot_processing.rs b/eth2/state_processing/src/per_slot_processing.rs
index a68f98c6d..8dbf65fa7 100644
--- a/eth2/state_processing/src/per_slot_processing.rs
+++ b/eth2/state_processing/src/per_slot_processing.rs
@@ -24,7 +24,8 @@ pub fn per_slot_processing(state: &mut BeaconState, spec: &ChainSpec) -> Result<
 }
 
 fn cache_state(state: &mut BeaconState, spec: &ChainSpec) -> Result<(), Error> {
-    let previous_slot_state_root = Hash256::from_slice(&state.tree_hash_root()[..]);
+    // let previous_slot_state_root = Hash256::from_slice(&state.tree_hash_root()[..]);
+    let previous_slot_state_root = state.update_tree_hash_cache()?;
 
     // Note: increment the state slot here to allow use of our `state_root` and `block_root`
     // getter/setter functions.