From a2d5a60418e70ce56112381dffdd121cc678a1b6 Mon Sep 17 00:00:00 2001
From: Felix Lange <fjl@twurst.com>
Date: Tue, 18 Aug 2015 14:14:45 +0200
Subject: core, core/state: batch-based state sync

---
 core/state/statedb.go | 86 +++++++++++++++++++++++++--------------------------
 1 file changed, 43 insertions(+), 43 deletions(-)

(limited to 'core/state/statedb.go')

diff --git a/core/state/statedb.go b/core/state/statedb.go
index c2bc99564..4233c763b 100644
--- a/core/state/statedb.go
+++ b/core/state/statedb.go
@@ -35,7 +35,6 @@ import (
 type StateDB struct {
 	db   ethdb.Database
 	trie *trie.SecureTrie
-	root common.Hash
 
 	stateObjects map[string]*StateObject
 
@@ -56,7 +55,6 @@ func New(root common.Hash, db ethdb.Database) *StateDB {
 		glog.Errorf("can't create state trie with root %x: %v", root[:], err)
 	}
 	return &StateDB{
-		root:         root,
 		db:           db,
 		trie:         tr,
 		stateObjects: make(map[string]*StateObject),
@@ -204,7 +202,6 @@ func (self *StateDB) UpdateStateObject(stateObject *StateObject) {
 	if len(stateObject.CodeHash()) > 0 {
 		self.db.Put(stateObject.CodeHash(), stateObject.code)
 	}
-
 	addr := stateObject.Address()
 	self.trie.Update(addr[:], stateObject.RlpEncode())
 }
@@ -215,6 +212,7 @@ func (self *StateDB) DeleteStateObject(stateObject *StateObject) {
 
 	addr := stateObject.Address()
 	self.trie.Delete(addr[:])
+	//delete(self.stateObjects, addr.Str())
 }
 
 // Retrieve a state object given my the address. Nil if not found
@@ -311,65 +309,67 @@ func (self *StateDB) Set(state *StateDB) {
 	self.logSize = state.logSize
 }
 
-func (s *StateDB) Root() common.Hash {
-	return s.trie.Hash()
-}
-
-// Syncs the trie and all siblings
-func (s *StateDB) Sync() {
-	// Sync all nested states
+// IntermediateRoot computes the current root hash of the state trie.
+// It is called in between transactions to get the root hash that
+// goes into transaction receipts.
+func (s *StateDB) IntermediateRoot() common.Hash {
+	s.refund = new(big.Int)
 	for _, stateObject := range s.stateObjects {
-		stateObject.trie.Commit()
-	}
-
-	s.trie.Commit()
-
-	s.Empty()
-}
-
-func (self *StateDB) Empty() {
-	self.stateObjects = make(map[string]*StateObject)
-	self.refund = new(big.Int)
-}
-
-func (self *StateDB) Refunds() *big.Int {
-	return self.refund
-}
-
-// SyncIntermediate updates the intermediate state and all mid steps
-func (self *StateDB) SyncIntermediate() {
-	self.refund = new(big.Int)
-
-	for _, stateObject := range self.stateObjects {
 		if stateObject.dirty {
 			if stateObject.remove {
-				self.DeleteStateObject(stateObject)
+				s.DeleteStateObject(stateObject)
 			} else {
 				stateObject.Update()
-
-				self.UpdateStateObject(stateObject)
+				s.UpdateStateObject(stateObject)
 			}
 			stateObject.dirty = false
 		}
 	}
+	return s.trie.Hash()
 }
 
-// SyncObjects syncs the changed objects to the trie
-func (self *StateDB) SyncObjects() {
-	self.trie, _ = trie.NewSecure(self.root, self.db)
+// Commit commits all state changes to the database.
+func (s *StateDB) Commit() (root common.Hash, err error) {
+	return s.commit(s.db)
+}
+
+// CommitBatch commits all state changes to a write batch but does not
+// execute the batch. It is used to validate state changes against
+// the root hash stored in a block.
+func (s *StateDB) CommitBatch() (root common.Hash, batch ethdb.Batch) {
+	batch = s.db.NewBatch()
+	root, _ = s.commit(batch)
+	return root, batch
+}
 
-	self.refund = new(big.Int)
+func (s *StateDB) commit(db trie.DatabaseWriter) (common.Hash, error) {
+	s.refund = new(big.Int)
 
-	for _, stateObject := range self.stateObjects {
+	for _, stateObject := range s.stateObjects {
 		if stateObject.remove {
-			self.DeleteStateObject(stateObject)
+			// If the object has been removed, don't bother syncing it
+			// and just mark it for deletion in the trie.
+			s.DeleteStateObject(stateObject)
 		} else {
+			// Write any storage changes in the state object to its trie.
 			stateObject.Update()
-
-			self.UpdateStateObject(stateObject)
+			// Commit the trie of the object to the batch.
+			// This updates the trie root internally, so
+			// getting the root hash of the storage trie
+			// through UpdateStateObject is fast.
+			if _, err := stateObject.trie.CommitTo(db); err != nil {
+				return common.Hash{}, err
+			}
+			// Update the object in the account trie.
+			s.UpdateStateObject(stateObject)
 		}
 		stateObject.dirty = false
 	}
+	return s.trie.CommitTo(db)
+}
+
+func (self *StateDB) Refunds() *big.Int {
+	return self.refund
 }
 
 // Debug stuff
-- 
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