/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.index;
import java.io.IOException;
/**
* An interface for implementations that support 2-phase commit. You can use
* {@link TwoPhaseCommitTool} to execute a 2-phase commit algorithm over several
* {@link TwoPhaseCommit}s.
*
* @lucene.experimental
*/
public interface TwoPhaseCommit {
/**
* The first stage of a 2-phase commit. Implementations should do as much work
* as possible in this method, but avoid actual committing changes. If the
* 2-phase commit fails, {@link #rollback()} is called to discard all changes
* since last successful commit.
*/
public long prepareCommit() throws IOException;
/**
* The second phase of a 2-phase commit. Implementations should ideally do
* very little work in this method (following {@link #prepareCommit()}, and
* after it returns, the caller can assume that the changes were successfully
* committed to the underlying storage.
*/
public long commit() throws IOException;
/**
* Discards any changes that have occurred since the last commit. In a 2-phase
* commit algorithm, where one of the objects failed to {@link #commit()} or
* {@link #prepareCommit()}, this method is used to roll all other objects
* back to their previous state.
*/
public void rollback() throws IOException;
}