From 88fd1b752ead6e5f31ac1f80914f60484a716c81 Mon Sep 17 00:00:00 2001
From: Jae Kwon <jae@tendermint.com>
Date: Thu, 12 Jan 2017 14:32:34 -0800
Subject: [PATCH] Cache updates to state.store in readCache

---
 app/app.go     |  4 +++-
 state/state.go | 37 +++++++++++++++++++++++++------------
 2 files changed, 28 insertions(+), 13 deletions(-)

diff --git a/app/app.go b/app/app.go
index 6e3b439ef..3c092f9d6 100644
--- a/app/app.go
+++ b/app/app.go
@@ -131,6 +131,9 @@ func (app *Basecoin) Commit() (res tmsp.Result) {
 	// Commit eyes.
 	res = app.eyesCli.CommitSync()
 
+	// Wrap the committed state in cache for CheckTx
+	app.cacheState = app.state.CacheWrap()
+
 	if res.IsErr() {
 		PanicSanity("Error getting hash: " + res.Error())
 	}
@@ -149,7 +152,6 @@ func (app *Basecoin) BeginBlock(height uint64) {
 	for _, plugin := range app.plugins.GetList() {
 		plugin.Plugin.BeginBlock(app.state, height)
 	}
-	app.cacheState = app.state.CacheWrap()
 }
 
 // TMSP::EndBlock
diff --git a/state/state.go b/state/state.go
index 3d767d6d8..901ee6887 100644
--- a/state/state.go
+++ b/state/state.go
@@ -9,15 +9,18 @@ import (
 // CONTRACT: State should be quick to copy.
 // See CacheWrap().
 type State struct {
-	chainID string
-	store   types.KVStore
-	cache   *types.KVCache // optional
+	chainID    string
+	store      types.KVStore
+	readCache  map[string][]byte // optional, for caching writes to store
+	writeCache *types.KVCache    // optional, for caching writes w/o writing to store
 }
 
 func NewState(store types.KVStore) *State {
 	return &State{
-		chainID: "",
-		store:   store,
+		chainID:    "",
+		store:      store,
+		readCache:  make(map[string][]byte),
+		writeCache: nil,
 	}
 }
 
@@ -33,33 +36,43 @@ func (s *State) GetChainID() string {
 }
 
 func (s *State) Get(key []byte) (value []byte) {
+	if s.readCache != nil {
+		value, ok := s.readCache[string(key)]
+		if ok {
+			return value
+		}
+	}
 	return s.store.Get(key)
 }
 
 func (s *State) Set(key []byte, value []byte) {
+	if s.readCache != nil {
+		s.readCache[string(key)] = value
+	}
 	s.store.Set(key, value)
 }
 
 func (s *State) GetAccount(addr []byte) *types.Account {
-	return GetAccount(s.store, addr)
+	return GetAccount(s, addr)
 }
 
 func (s *State) SetAccount(addr []byte, acc *types.Account) {
-	SetAccount(s.store, addr, acc)
+	SetAccount(s, addr, acc)
 }
 
 func (s *State) CacheWrap() *State {
-	cache := types.NewKVCache(s.store)
+	cache := types.NewKVCache(s)
 	return &State{
-		chainID: s.chainID,
-		store:   cache,
-		cache:   cache,
+		chainID:    s.chainID,
+		store:      cache,
+		readCache:  nil,
+		writeCache: cache,
 	}
 }
 
 // NOTE: errors if s is not from CacheWrap()
 func (s *State) CacheSync() {
-	s.cache.Sync()
+	s.writeCache.Sync()
 }
 
 //----------------------------------------