core, params: polish net gas metering PR a bit

core/state/state_object.go

@@ -77,9 +77,9 @@ type stateObject struct {
 	trie Trie // storage trie, which becomes non-nil on first access
 	code Code // contract bytecode, which gets set when code is loaded
 
-	cachedStorage Storage // Storage entry cache to avoid duplicate reads
+	originStorage Storage // Storage cache of original entries to dedup rewrites
 	dirtyStorage  Storage // Storage entries that need to be flushed to disk
-	originalValue Storage // Map of original storage values, at the beginning of current call context
+
 	// Cache flags.
 	// When an object is marked suicided it will be delete from the trie
 	// during the "update" phase of the state transition.
@@ -115,9 +115,8 @@ func newObject(db *StateDB, address common.Address, data Account) *stateObject {
 		address:       address,
 		addrHash:      crypto.Keccak256Hash(address[:]),
 		data:          data,
-		cachedStorage: make(Storage),
+		originStorage: make(Storage),
 		dirtyStorage:  make(Storage),
-		originalValue: make(Storage),
 	}
 }
 
@@ -160,13 +159,25 @@ func (c *stateObject) getTrie(db Database) Trie {
 	return c.trie
 }
 
-// GetState returns a value in account storage.
+// GetState retrieves a value from the account storage trie.
 func (self *stateObject) GetState(db Database, key common.Hash) common.Hash {
-	value, exists := self.cachedStorage[key]
-	if exists {
+	// If we have a dirty value for this state entry, return it
+	value, dirty := self.dirtyStorage[key]
+	if dirty {
 		return value
 	}
-	// Load from DB in case it is missing.
+	// Otherwise return the entry's original value
+	return self.GetCommittedState(db, key)
+}
+
+// GetCommittedState retrieves a value from the committed account storage trie.
+func (self *stateObject) GetCommittedState(db Database, key common.Hash) common.Hash {
+	// If we have the original value cached, return that
+	value, cached := self.originStorage[key]
+	if cached {
+		return value
+	}
+	// Otherwise load the value from the database
 	enc, err := self.getTrie(db).TryGet(key[:])
 	if err != nil {
 		self.setError(err)
@@ -179,37 +190,27 @@ func (self *stateObject) GetState(db Database, key common.Hash) common.Hash {
 		}
 		value.SetBytes(content)
 	}
-	self.cachedStorage[key] = value
+	self.originStorage[key] = value
 	return value
 }
 
-// GetOriginalStateValue returns the state value that is currently in the Trie, that is, ignoring any
-// changes that have been made but not yet written to trie.
-func (self *stateObject) GetOriginalStateValue(db Database, key common.Hash) common.Hash{
-	if original, exist:= self.originalValue[key]; exist {
-		// original value has been set, return it
-		return original
-	}
-	return self.GetState(db, key)
-}
-
 // SetState updates a value in account storage.
 func (self *stateObject) SetState(db Database, key, value common.Hash) {
+	// If the new value is the same as old, don't set
 	prev := self.GetState(db, key)
+	if prev == value {
+		return
+	}
+	// New value is different, update and journal the change
 	self.db.journal.append(storageChange{
 		account:  &self.address,
 		key:      key,
 		prevalue: prev,
 	})
-	if _, isSet := self.originalValue[key]; !isSet {
-		// original value has not been set, so set it now
-		self.originalValue[key] = prev
-	}
 	self.setState(key, value)
 }
 
 func (self *stateObject) setState(key, value common.Hash) {
-	self.cachedStorage[key] = value
 	self.dirtyStorage[key] = value
 }
 
@@ -218,6 +219,13 @@ func (self *stateObject) updateTrie(db Database) Trie {
 	tr := self.getTrie(db)
 	for key, value := range self.dirtyStorage {
 		delete(self.dirtyStorage, key)
+
+		// Skip noop changes, persist actual changes
+		if value == self.originStorage[key] {
+			continue
+		}
+		self.originStorage[key] = value
+
 		if (value == common.Hash{}) {
 			self.setError(tr.TryDelete(key[:]))
 			continue
@@ -226,10 +234,6 @@ func (self *stateObject) updateTrie(db Database) Trie {
 		v, _ := rlp.EncodeToBytes(bytes.TrimLeft(value[:], "\x00"))
 		self.setError(tr.TryUpdate(key[:], v))
 	}
-	// Clean the map containing 'original' value of storage entries
-	for k, _ := range self.originalValue {
-		delete(self.originalValue, k)
-	}
 	return tr
 }
 
@@ -299,8 +303,7 @@ func (self *stateObject) deepCopy(db *StateDB) *stateObject {
 	}
 	stateObject.code = self.code
 	stateObject.dirtyStorage = self.dirtyStorage.Copy()
-	stateObject.cachedStorage = self.dirtyStorage.Copy()
-	stateObject.originalValue = self.originalValue.Copy()
+	stateObject.originStorage = self.originStorage.Copy()
 	stateObject.suicided = self.suicided
 	stateObject.dirtyCode = self.dirtyCode
 	stateObject.deleted = self.deleted