1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 package org.apache.giraph.comm.netty.handler; 20 21 import com.google.common.collect.Maps; 22 import java.util.concurrent.ConcurrentMap; 23 import java.util.concurrent.atomic.AtomicLong; 24 25 /** 26 * Generate different request ids based on the task id. Thread-safe. 27 */ 28 public class TaskRequestIdGenerator { 29 /** Task request generator map */ 30 private final ConcurrentMap<Integer, AtomicLong> 31 taskRequestGeneratorMap = Maps.newConcurrentMap(); 32 33 /** 34 * Get the next request id for a given destination. Thread-safe. 35 * 36 * @param taskId id of the task(consistent during a superstep) 37 * @return Valid request id 38 */ 39 public Long getNextRequestId(Integer taskId) { 40 AtomicLong requestGenerator = taskRequestGeneratorMap.get(taskId); 41 if (requestGenerator == null) { 42 requestGenerator = new AtomicLong(0); 43 AtomicLong oldRequestGenerator = 44 taskRequestGeneratorMap.putIfAbsent(taskId, requestGenerator); 45 if (oldRequestGenerator != null) { 46 requestGenerator = oldRequestGenerator; 47 } 48 } 49 return requestGenerator.getAndIncrement(); 50 } 51 }