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.impl;
018
019import java.util.Set;
020import java.util.concurrent.CopyOnWriteArraySet;
021
022import org.apache.camel.CamelContext;
023import org.apache.camel.Endpoint;
024import org.apache.camel.Ordered;
025import org.apache.camel.ResolveEndpointFailedException;
026import org.apache.camel.Service;
027import org.apache.camel.StartupListener;
028import org.apache.camel.util.ServiceHelper;
029
030/**
031 * A {@link org.apache.camel.StartupListener} that defers starting {@link Service}s, until as late as possible during
032 * the startup process of {@link CamelContext}.
033 */
034public class DeferServiceStartupListener implements StartupListener, Ordered {
035
036    private final Set<Service> services = new CopyOnWriteArraySet<Service>();
037
038    public void addService(Service service) {
039        services.add(service);
040    }
041
042    @Override
043    public void onCamelContextStarted(CamelContext context, boolean alreadyStarted) throws Exception {
044        // new services may be added while starting a service
045        // so use a while loop to get the newly added services as well
046        while (!services.isEmpty()) {
047            Service service = services.iterator().next();
048            try {
049                ServiceHelper.startService(service);
050            } catch (Exception e) {
051                if (service instanceof Endpoint) {
052                    Endpoint endpoint = (Endpoint) service;
053                    throw new ResolveEndpointFailedException(endpoint.getEndpointUri(), e);
054                } else {
055                    throw e;
056                }
057            } finally {
058                services.remove(service);
059            }
060        }
061    }
062
063    public int getOrder() {
064        // we want to be last, so the other startup listeners run first
065        return Ordered.LOWEST;
066    }
067}