// (c) 2019-2020, Ava Labs, Inc. All rights reserved.
// See the file LICENSE for licensing terms.

// For ease of implementation, our database's interface matches Ethereum's
// database implementation. This was to allow use to use Geth code as is for the
// EVM chain.

package database

// 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 {
	KeyValueWriter

	// 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()

	// Replay replays the batch contents.
	Replay(w KeyValueWriter) error

	// Inner returns a Batch writing to the inner database, if one exists. If
	// this batch is already writing to the base DB, then itself should be
	// returned.
	Inner() Batch
}

// 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
}