/**
* 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.state;
import backtype.storm.topology.IStatefulBolt;
/**
* The state of the component that is either managed by the framework (e.g in case of {@link IStatefulBolt})
* or managed by the the individual components themselves.
*/
public interface State {
/**
* Invoked by the framework to prepare a transaction for commit. It should be possible
* to commit the prepared state later.
* <p>
* The same txid can be prepared again, but the next txid cannot be prepared
* when previous one is not yet committed.
* </p>
*
* @param txid the transaction id
*/
void prepareCommit(long txid);
/**
* Commit a previously prepared transaction. It should be possible to retrieve a committed state later.
*
* @param txid the transaction id
*/
void commit(long txid);
/**
* Persist the current state. This is used when the component manages the state.
*/
void commit();
/**
* Rollback a prepared transaction to the previously committed state.
*/
void rollback();
}