package org.apache.fulcrum.yaafi.service.shutdown;
   
   /*
    * 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.
   */
  
  import java.io.File;
  import java.security.MessageDigest;
  
  import org.apache.avalon.framework.activity.Disposable;
  import org.apache.avalon.framework.activity.Initializable;
  import org.apache.avalon.framework.activity.Startable;
  import org.apache.avalon.framework.configuration.Configuration;
  import org.apache.avalon.framework.configuration.ConfigurationException;
  import org.apache.avalon.framework.configuration.Reconfigurable;
  import org.apache.avalon.framework.context.Context;
  import org.apache.avalon.framework.context.ContextException;
  import org.apache.avalon.framework.context.Contextualizable;
  import org.apache.avalon.framework.logger.AbstractLogEnabled;
  import org.apache.avalon.framework.service.ServiceException;
  import org.apache.avalon.framework.service.ServiceManager;
  import org.apache.avalon.framework.service.Serviceable;
  
  /**
   * Monitors the componentConfiguration.xml and triggers a reconfiguration if the
   * content of the component configuration file has changed.
   *
   * @author <a href="mailto:siegfried.goeschl@it20one.at">Siegfried Goeschl</a>
   */
  
  public class ShutdownServiceImpl extends AbstractLogEnabled implements ShutdownService, Serviceable, Contextualizable,
  		Reconfigurable, Initializable, Runnable, Startable, Disposable {
  	/** the interval between two checks in ms */
  	private int interval;
  
  	/** shall the worker thread terminate immediately */
  	private boolean terminateNow;
  
  	/** the worker thread polling the resource */
  	private Thread workerThread;
  
  	/** the ServiceManager to use */
  	private ServiceManager serviceManager;
  
  	/** the application directory */
  	private File applicationDir;
  
  	/** our own and only shutdown entry */
  	private ShutdownEntry shutdownEntry;
  
  	/////////////////////////////////////////////////////////////////////////
  	// Avalon Service Lifecycle Implementation
  	/////////////////////////////////////////////////////////////////////////
  
  	/**
  	 * Constructor
  	 */
  	public ShutdownServiceImpl() {
  		this.terminateNow = false;
  	}
  
  	/**
  	 * @see org.apache.avalon.framework.service.Serviceable#service(org.apache.avalon.framework.service.ServiceManager)
  	 */
  	public void service(ServiceManager manager) throws ServiceException {
  		this.serviceManager = manager;
  	}
  
  	/**
  	 * @see org.apache.avalon.framework.context.Contextualizable#contextualize(org.apache.avalon.framework.context.Context)
  	 */
  	public void contextualize(Context context) throws ContextException {
  		this.applicationDir = (File) context.get("urn:avalon:home");
  	}
  
  	/**
  	 * @see org.apache.avalon.framework.configuration.Configurable#configure(org.apache.avalon.framework.configuration.Configuration)
  	 */
  	public void configure(Configuration configuration) throws ConfigurationException {
  		// limit to minimum interval of 1 second
  
  		this.interval = Math.max(configuration.getAttributeAsInteger("interval", 5000), 1000);
  
  		this.getLogger().debug("Monitoring the resources every " + this.interval + " ms");
 
 		if (configuration.getChild("entry", false) != null) {
 			Configuration shutdownConfig = configuration.getChild("entry");
 
 			String shutdownEntryLocation = shutdownConfig.getChild("location").getValue();
 
 			this.shutdownEntry = new ShutdownEntry(this.getLogger(), this.applicationDir, shutdownEntryLocation,
 					shutdownConfig.getChild("useSystemExit").getValueAsBoolean(false));
 
 			this.getLogger().debug("Using a shutdown entry : " + shutdownEntryLocation);
 		} else {
 			this.shutdownEntry = null;
 			this.getLogger().debug("No shutdown entry defined");
 		}
 	}
 
 	/*
 	 * (non-Javadoc)
 	 * 
 	 * @see org.apache.avalon.framework.activity.Initializable#initialize()
 	 */
 	public void initialize() throws Exception {
 
 		// request a SHA-1 to make sure that it is supported
 		MessageDigest.getInstance("SHA1");
 
 		// check that the ServiceManager inplements Disposable
 		if (this.serviceManager instanceof Disposable == false) {
 			String msg = "The ServiceManager instance does not implement Disposable?!";
 			throw new IllegalArgumentException(msg);
 		}
 
 		// create the worker thread polling the target
 		this.workerThread = new Thread(this, "ShutdownService");
 	}
 
 	/*
 	 * (non-Javadoc)
 	 * 
 	 * @see org.apache.avalon.framework.activity.Startable#start()
 	 */
 	public void start() throws Exception {
 		this.getLogger().debug("Starting worker thread ...");
 		this.workerThread.start();
 	}
 
 	/**
 	 * @see org.apache.avalon.framework.activity.Startable#stop()
 	 */
 	public void stop() throws Exception {
 		this.getLogger().debug("Stopping worker thread ...");
 		this.terminateNow = true;
 		this.workerThread.interrupt();
 		this.workerThread.join(10000);
 	}
 
 	/**
 	 * @see org.apache.avalon.framework.activity.Disposable#dispose()
 	 */
 	public void dispose() {
 		this.terminateNow = false;
 		this.applicationDir = null;
 		this.workerThread = null;
 		this.serviceManager = null;
 	}
 
 	/**
 	 * @see org.apache.avalon.framework.configuration.Reconfigurable#reconfigure(org.apache.avalon.framework.configuration.Configuration)
 	 */
 	public void reconfigure(Configuration configuration) throws ConfigurationException {
 		this.configure(configuration);
 	}
 
 	/////////////////////////////////////////////////////////////////////////
 	// Service interface implementation
 	/////////////////////////////////////////////////////////////////////////
 
 	/* (non-Javadoc)
 	 * @see java.lang.Runnable#run()
 	 */
 	public void run() {
 		while (this.terminateNow == false) {
 			try {
 				Thread.sleep(this.interval);
 			} catch (InterruptedException e) {
 				// nothing to do
 			}
 
 			if (this.hasShutdownEntry() && this.getShutdownEntry().hasChanged()
 					&& this.serviceManager instanceof Disposable) {
 
 				if (this.getShutdownEntry().isUseSystemExit()) {
 					this.getLogger().warn("Forcing a shutdown using System.exit() ...");
 				} else {
 					this.getLogger().warn("Forcing a shutdown ...");
 				}
 
 				// create a demon thread to shutdown the container
 				Shutdown shutdown = new Shutdown((Disposable) this.serviceManager,
 						this.getShutdownEntry().isUseSystemExit());
 
 				Thread shutdownThread = new Thread(shutdown, "ShutdownServiceThread");
 				shutdownThread.setDaemon(true);
 				shutdownThread.start();
 			}
 		}
 	}
 
 	/////////////////////////////////////////////////////////////////////////
 	// Service implementation
 	/////////////////////////////////////////////////////////////////////////
 
 	/**
 	 * @return Returns the shutdownEntry.
 	 */
 	private ShutdownEntry getShutdownEntry() {
 		return this.shutdownEntry;
 	}
 
 	/**
 	 * @return Is a shutdown entry defined?
 	 */
 	private boolean hasShutdownEntry() {
 		return (this.shutdownEntry != null ? true : false);
 	}
 }