/**
    * Copyright 2005-2015 The Kuali Foundation
    *
    * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
    *
   * 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.kuali.rice.ksb.impl.bus;
  
  import org.kuali.rice.ksb.api.bus.Endpoint;
  import org.kuali.rice.ksb.api.bus.ServiceConfiguration;
  import org.kuali.rice.ksb.messaging.serviceconnectors.ServiceConnectorFactory;
  
  public class LazyEndpoint implements Endpoint {
  
  	private final Object lock = new Object();
  	
  	private final ServiceConfiguration serviceConfiguration;
  	private volatile Object service;
  	
  	public LazyEndpoint(ServiceConfiguration serviceConfiguration) {
  		if (serviceConfiguration == null) {
  			throw new IllegalArgumentException("serviceConfiguration was null");
  		}
  		this.serviceConfiguration = serviceConfiguration;
  	}
  	
  	@Override
  	public ServiceConfiguration getServiceConfiguration() {
  		return this.serviceConfiguration;
  	}
  
  	@Override
  	public Object getService() {
  		// double-checked locking idiom - see Effective Java, Item 71
  		Object internalService = this.service;
  		if (internalService == null) {
  			synchronized (lock) {
  				internalService = this.service;
  				if (internalService == null) {
  					this.service = internalService = ServiceConnectorFactory.getServiceConnector(serviceConfiguration).getService(); 
  				}
  			}
  		}
  		return internalService;
  	}
  
  }