001/** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.camel.processor.loadbalancer; 018 019import java.util.ArrayList; 020import java.util.List; 021import java.util.concurrent.CopyOnWriteArrayList; 022 023import org.apache.camel.Exchange; 024import org.apache.camel.Navigate; 025import org.apache.camel.Processor; 026import org.apache.camel.support.ServiceSupport; 027import org.apache.camel.util.AsyncProcessorHelper; 028import org.apache.camel.util.ServiceHelper; 029import org.slf4j.Logger; 030import org.slf4j.LoggerFactory; 031 032/** 033 * A default base class for a {@link LoadBalancer} implementation. 034 * <p/> 035 * This implementation is dedicated for asynchronous load balancers. 036 * <p/> 037 * Consider using the {@link SimpleLoadBalancerSupport} if your load balancer does not by nature 038 * support asynchronous routing. 039 * 040 * @version 041 */ 042public abstract class LoadBalancerSupport extends ServiceSupport implements LoadBalancer, Navigate<Processor> { 043 044 protected final Logger log = LoggerFactory.getLogger(getClass()); 045 private final List<Processor> processors = new CopyOnWriteArrayList<Processor>(); 046 047 public void addProcessor(Processor processor) { 048 processors.add(processor); 049 } 050 051 public void removeProcessor(Processor processor) { 052 processors.remove(processor); 053 } 054 055 public List<Processor> getProcessors() { 056 return processors; 057 } 058 059 public List<Processor> next() { 060 if (!hasNext()) { 061 return null; 062 } 063 return new ArrayList<Processor>(processors); 064 } 065 066 public boolean hasNext() { 067 return processors.size() > 0; 068 } 069 070 protected void doStart() throws Exception { 071 ServiceHelper.startServices(processors); 072 } 073 074 protected void doStop() throws Exception { 075 ServiceHelper.stopServices(processors); 076 } 077 078 @Override 079 protected void doShutdown() throws Exception { 080 ServiceHelper.stopAndShutdownServices(processors); 081 for (Processor processor : processors) { 082 removeProcessor(processor); 083 } 084 } 085 086 public void process(Exchange exchange) throws Exception { 087 AsyncProcessorHelper.process(this, exchange); 088 } 089}