content: /**
   * 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();
  }
  