| /** |
| * 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.state; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.util.Map; |
| import java.util.concurrent.ConcurrentHashMap; |
| |
| /** |
| * An in-memory implementation of the {@link State} |
| */ |
| public class InMemoryKeyValueState<K, V> implements KeyValueState<K, V> { |
| private static final Logger LOG = LoggerFactory.getLogger(InMemoryKeyValueState.class); |
| private static final long DEFAULT_TXID = -1; |
| private TxIdState<K, V> commitedState; |
| private TxIdState<K, V> preparedState; |
| private Map<K, V> state = new ConcurrentHashMap<>(); |
| |
| private static class TxIdState<K, V> { |
| private long txid; |
| private Map<K, V> state; |
| |
| TxIdState(long txid, Map<K, V> state) { |
| this.txid = txid; |
| this.state = state; |
| } |
| |
| @Override |
| public String toString() { |
| return "TxIdState{" + |
| "txid=" + txid + |
| ", state=" + state + |
| '}'; |
| } |
| } |
| |
| @Override |
| public void put(K key, V value) { |
| state.put(key, value); |
| } |
| |
| @Override |
| public V get(K key) { |
| return state.get(key); |
| } |
| |
| @Override |
| public V get(K key, V defaultValue) { |
| V val = get(key); |
| return val != null ? val : defaultValue; |
| } |
| |
| @Override |
| public void commit() { |
| commitedState = new TxIdState<>(DEFAULT_TXID, new ConcurrentHashMap<>(state)); |
| } |
| |
| @Override |
| public void prepareCommit(long txid) { |
| LOG.debug("prepare commit, txid {}", txid); |
| if (preparedState != null && txid > preparedState.txid) { |
| throw new RuntimeException("Cannot prepare a new txn while there is a pending txn"); |
| } |
| preparedState = new TxIdState<>(txid, new ConcurrentHashMap<K, V>(state)); |
| } |
| |
| @Override |
| public void commit(long txid) { |
| LOG.debug("commit, txid {}", txid); |
| if (preparedState != null && txid == preparedState.txid) { |
| commitedState = preparedState; |
| preparedState = null; |
| } else { |
| throw new RuntimeException("Invalid prepared state for commit, " + |
| "preparedState " + preparedState + " txid " + txid); |
| } |
| } |
| |
| @Override |
| public void rollback() { |
| preparedState = null; |
| if (commitedState != null) { |
| state = commitedState.state; |
| } else { |
| state = new ConcurrentHashMap<>(); |
| } |
| } |
| |
| @Override |
| public String toString() { |
| return "InMemoryKeyValueState{" + |
| "commitedState=" + commitedState + |
| ", preparedState=" + preparedState + |
| ", state=" + state + |
| '}'; |
| } |
| } |