storm-client/src/jvm/org/apache/storm/trident/state/State.java

/**
 * 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.storm.trident.state;

/**
 * There's 3 different kinds of state:
 *
 * 1. non-transactional: ignores commits, updates are permanent. no rollback. a cassandra incrementing state would be like this 2.
 * repeat-transactional: idempotent as long as all batches for a txid are identical 3. opaque-transactional: the most general kind of state.
 * updates are always done based on the previous version of the value if the current commit = latest stored commit Idempotent even if the
 * batch for a txid can change.
 *
 * repeat transactional is idempotent for transactional spouts opaque transactional is idempotent for opaque or transactional spouts
 *
 * Trident should log warnings when state is idempotent but updates will not be idempotent because of spout
 */
// retrieving is encapsulated in Retrieval interface
public interface State {
    void beginCommit(Long txid); // can be null for things like partitionPersist occuring off a DRPC stream

    void commit(Long txid);
}