| /** |
| * 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.streams.processors; |
| |
| import org.apache.storm.state.KeyValueState; |
| import org.apache.storm.streams.Pair; |
| import org.apache.storm.streams.operations.StateUpdater; |
| |
| public class UpdateStateByKeyProcessor<K, V, R> extends BaseProcessor<Pair<K, V>> implements StatefulProcessor<K, R> { |
| private final StateUpdater<V, R> stateUpdater; |
| private KeyValueState<K, R> keyValueState; |
| |
| public UpdateStateByKeyProcessor(StateUpdater<V, R> stateUpdater) { |
| this.stateUpdater = stateUpdater; |
| } |
| |
| @Override |
| public void initState(KeyValueState<K, R> keyValueState) { |
| this.keyValueState = keyValueState; |
| } |
| |
| @Override |
| protected void execute(Pair<K, V> input) { |
| K key = input.getFirst(); |
| V val = input.getSecond(); |
| R agg = keyValueState.get(key); |
| if (agg == null) { |
| agg = stateUpdater.init(); |
| } |
| R newAgg = stateUpdater.apply(agg, val); |
| keyValueState.put(key, newAgg); |
| context.forward(Pair.of(key, newAgg)); |
| } |
| } |