| /** |
| * 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 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); |
| } |
