From 3c26ba4d307bf32ac3d17ab6d3f996096a102b51 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A9ter=20Szil=C3=A1gyi?= <peterke@gmail.com>
Date: Fri, 23 Sep 2016 08:57:51 +0300
Subject: [PATCH] state: track code dirtyness and only write if changed

---
 core/state/state_object.go | 10 ++++++----
 core/state/statedb.go      |  3 ++-
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/core/state/state_object.go b/core/state/state_object.go
index 5f30177cde..0379af2de2 100644
--- a/core/state/state_object.go
+++ b/core/state/state_object.go
@@ -82,9 +82,10 @@ type StateObject struct {
 	// Cache flags.
 	// When an object is marked for deletion it will be delete from the trie
 	// during the "update" phase of the state transition
-	dirty   bool // true if anything has changed
-	remove  bool
-	deleted bool
+	dirty     bool // true if anything has changed
+	dirtyCode bool // true if the code was updated
+	remove    bool
+	deleted   bool
 }
 
 // Account is the Ethereum consensus representation of accounts.
@@ -238,6 +239,7 @@ func (self *StateObject) Copy(db trie.Database) *StateObject {
 	stateObject.storage = self.storage.Copy()
 	stateObject.remove = self.remove
 	stateObject.dirty = self.dirty
+	stateObject.dirtyCode = self.dirtyCode
 	stateObject.deleted = self.deleted
 	return stateObject
 }
@@ -270,7 +272,7 @@ func (self *StateObject) Code(db trie.Database) []byte {
 func (self *StateObject) SetCode(code []byte) {
 	self.code = code
 	self.data.CodeHash = crypto.Keccak256(code)
-	self.dirty = true
+	self.dirty, self.dirtyCode = true, true
 }
 
 func (self *StateObject) SetNonce(nonce uint64) {
diff --git a/core/state/statedb.go b/core/state/statedb.go
index 6d69a9e51e..097e5a1a6f 100644
--- a/core/state/statedb.go
+++ b/core/state/statedb.go
@@ -447,10 +447,11 @@ func (s *StateDB) commit(dbw trie.DatabaseWriter) (root common.Hash, err error)
 			delete(s.all, addr)
 		} else if stateObject.dirty {
 			// Write any contract code associated with the state object
-			if stateObject.code != nil {
+			if stateObject.code != nil && stateObject.dirtyCode {
 				if err := dbw.Put(stateObject.CodeHash(), stateObject.code); err != nil {
 					return common.Hash{}, err
 				}
+				stateObject.dirtyCode = false
 			}
 			// Write any storage changes in the state object to its storage trie.
 			if err := stateObject.CommitTrie(s.db, dbw); err != nil {