| /** |
| * 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: |
| * |
| * <p>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. |
| * |
| * <p>repeat transactional is idempotent for transactional spouts opaque transactional is idempotent for opaque or transactional spouts |
| * |
| * <p>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); |
| } |