/**
* 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 backtype.storm.topology;
import backtype.storm.state.State;
/**
* <p>
* Common methods for stateful components in the topology.
* </p>
* A stateful component is one that has state (e.g. the result of some computation in a bolt)
* and wants the framework to manage its state.
*/
public interface IStatefulComponent<T extends State> extends IComponent {
/**
* This method is invoked by the framework with the previously
* saved state of the component. This is invoked after prepare but before
* the component starts processing tuples.
*
* @param state the previously saved state of the component.
*/
void initState(T state);
/**
* This is a hook for the component to perform some actions just before the
* framework commits its state.
*/
void preCommit(long txid);
/**
* This is a hook for the component to perform some actions just before the
* framework prepares its state.
*/
void prePrepare(long txid);
/**
* This is a hook for the component to perform some actions just before the
* framework rolls back the prepared state.
*/
void preRollback();
}