3 files changed, 79 insertions, 16 deletions

diff --git a/ethdb/database.go b/ethdb/database.go
index 9e80e5409..047821c30 100644
--- a/ethdb/database.go
+++ b/ethdb/database.go
@@ -61,9 +61,7 @@ type LDBDatabase struct {
 	quitChan chan chan error // Quit channel to stop the metrics collection before closing the database
 }
 
-// NewLDBDatabase returns a LevelDB wrapped object. LDBDatabase does not persist data by
-// it self but requires a background poller which syncs every X. `Flush` should be called
-// when data needs to be stored and written to disk.
+// NewLDBDatabase returns a LevelDB wrapped object.
 func NewLDBDatabase(file string, cache int) (*LDBDatabase, error) {
 	// Calculate the cache allowance for this particular database
 	cache = int(float64(cache) * cacheRatio[filepath.Base(file)])
@@ -142,11 +140,6 @@ func (self *LDBDatabase) NewIterator() iterator.Iterator {
 	return self.db.NewIterator(nil, nil)
 }
 
-// Flush flushes out the queue to leveldb
-func (self *LDBDatabase) Flush() error {
-	return nil
-}
-
 func (self *LDBDatabase) Close() {
 	// Stop the metrics collection to avoid internal database races
 	self.quitLock.Lock()
@@ -159,12 +152,14 @@ func (self *LDBDatabase) Close() {
 			glog.V(logger.Error).Infof("metrics failure in '%s': %v\n", self.fn, err)
 		}
 	}
-	// Flush and close the database
-	if err := self.Flush(); err != nil {
-		glog.V(logger.Error).Infof("flushing '%s' failed: %v\n", self.fn, err)
+	err := self.db.Close()
+	if glog.V(logger.Error) {
+		if err == nil {
+			glog.Infoln("closed db:", self.fn)
+		} else {
+			glog.Errorf("error closing db %s: %v", self.fn, err)
+		}
 	}
-	self.db.Close()
-	glog.V(logger.Error).Infoln("flushed and closed db:", self.fn)
 }
 
 func (self *LDBDatabase) LDB() *leveldb.DB {
@@ -268,3 +263,23 @@ func (self *LDBDatabase) meter(refresh time.Duration) {
 		}
 	}
 }
+
+// TODO: remove this stuff and expose leveldb directly
+
+func (db *LDBDatabase) NewBatch() Batch {
+	return &ldbBatch{db: db.db, b: new(leveldb.Batch)}
+}
+
+type ldbBatch struct {
+	db *leveldb.DB
+	b  *leveldb.Batch
+}
+
+func (b *ldbBatch) Put(key, value []byte) error {
+	b.b.Put(key, value)
+	return nil
+}
+
+func (b *ldbBatch) Write() error {
+	return b.db.Write(b.b, nil)
+}
diff --git a/ethdb/interface.go b/ethdb/interface.go
new file mode 100644
index 000000000..f4b787a52
--- /dev/null
+++ b/ethdb/interface.go
@@ -0,0 +1,30 @@
+// Copyright 2014 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package ethdb
+
+type Database interface {
+	Put(key []byte, value []byte) error
+	Get(key []byte) ([]byte, error)
+	Delete(key []byte) error
+	Close()
+	NewBatch() Batch
+}
+
+type Batch interface {
+	Put(key, value []byte) error
+	Write() error
+}
diff --git a/ethdb/memory_database.go b/ethdb/memory_database.go
index d50f8f9d4..81911f23f 100644
--- a/ethdb/memory_database.go
+++ b/ethdb/memory_database.go
@@ -36,8 +36,7 @@ func NewMemDatabase() (*MemDatabase, error) {
 }
 
 func (db *MemDatabase) Put(key []byte, value []byte) error {
-	db.db[string(key)] = value
-
+	db.db[string(key)] = common.CopyBytes(value)
 	return nil
 }
 
@@ -92,6 +91,25 @@ func (db *MemDatabase) LastKnownTD() []byte {
 	return data
 }
 
-func (db *MemDatabase) Flush() error {
+func (db *MemDatabase) NewBatch() Batch {
+	return &memBatch{db: db}
+}
+
+type kv struct{ k, v []byte }
+
+type memBatch struct {
+	db     *MemDatabase
+	writes []kv
+}
+
+func (w *memBatch) Put(key, value []byte) error {
+	w.writes = append(w.writes, kv{key, common.CopyBytes(value)})
+	return nil
+}
+
+func (w *memBatch) Write() error {
+	for _, kv := range w.writes {
+		w.db.db[string(kv.k)] = kv.v
+	}
 	return nil
 }