all: clean up and proerly abstract database access

ethdb/batch.go

@@ -0,0 +1,44 @@
+// Copyright 2018 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
+
+// IdealBatchSize defines the size of the data batches should ideally add in one
+// write.
+const IdealBatchSize = 100 * 1024
+
+// Batch is a write-only database that commits changes to its host database
+// when Write is called. A batch cannot be used concurrently.
+type Batch interface {
+	Writer
+	Deleter
+
+	// ValueSize retrieves the amount of data queued up for writing.
+	ValueSize() int
+
+	// Write flushes any accumulated data to disk.
+	Write() error
+
+	// Reset resets the batch for reuse
+	Reset()
+}
+
+// Batcher wraps the NewBatch method of a backing data store.
+type Batcher interface {
+	// NewBatch creates a write-only database that buffers changes to its host db
+	// until a final write is called.
+	NewBatch() Batch
+}