/*
    * Copyright 2000-2001,2004 The Apache Software Foundation.
    * 
    * Licensed 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.
   */
  
  package org.apache.jetspeed.services.threadpool;
  
  //turbine stuff
  import org.apache.turbine.services.TurbineServices;
  
  // Jetspeed classes
  import org.apache.jetspeed.services.logging.JetspeedLogFactoryService;
  import org.apache.jetspeed.services.logging.JetspeedLogger;
  
  /***
   * A thread that is used to process Runnables.  This thread will wait until it is 
   * notified by another thread that it needs processing.  However it will only 
   * process if getRunnable != null.
   *
   * @author <a href="mailto:burton@apache.org">Kevin A. Burton</a>
   * @author <a href="mailto:sgala@apache.org">Santiago Gala</a>
   * @version $Id: RunnableThread.java,v 1.7 2004/02/23 03:51:31 jford Exp $
   */
  public class RunnableThread extends Thread 
  {
      /***
       * Static initialization of the logger for this class
       */    
      private static final JetspeedLogger logger = JetspeedLogFactoryService.getLogger(RunnableThread.class.getName());
      
      private boolean running = false;
      private static int next_id = 0;
  
      /***
       * Increment a counter so that we can identify threads
       * easily.
       */
      private static synchronized int getNextId() {
          return ++next_id;
      };
      private int id = 0;
  
      /***
      The runnable that you want to process
      */
      private Runnable runnable = null;
      
      public RunnableThread()
      {
          super();
          this.setDaemon(true);
      }
  
      /***
       * Creates a new Thread in the specified threadgroup
       *
       * @param tg the Threadgroup which will contain the new Thread
       */
      public RunnableThread( ThreadGroup tg) {
          super( tg, "Provisory");
          this.id = getNextId();
          super.setName("RunnableThread:" + this.id );
          this.setPriority( Thread.MIN_PRIORITY );
          this.setDaemon(true);
  
      }
  
      /***
       * Creates a new Thread in the specified threadgroup and assigns
       * it an id.
       *
       * @param tg the Threadgroup which will contain the new Thread
       * @param id an identifier for the new Thread
       */
      public RunnableThread( ThreadGroup tg, 
                             int id ) {
  
          super( tg, "RunnableThread:" + id );
          this.setPriority( Thread.MIN_PRIORITY );
          this.setDaemon(true);       
          this.id = id;
      }
      
      /***
       * Processes the Runnable object assigned to it, whenever one
       * is available
       */
      public void run() {
 
         /*
           FIXME: move to a static class variable to allow for pool shutdown
         */
         boolean poolrunning  = true;
         while ( poolrunning ) {
 
 
             //On creation, we are idle.
             //So, add ourselves to the Pool.
             //Next times we come here, we are just finished
             //one run...
             this.setRunning( false );                
 
             this.setRunnable( null );
                 
             synchronized( this ) {
                 if( this.getPriority() != 
                     JetspeedThreadPoolService.DEFAULT_THREAD_PRIORITY ) {
                     //give the thread back it's default priority.
                     this.setPriority( JetspeedThreadPoolService.DEFAULT_THREAD_PRIORITY );
                 }
                 
                 //SGP I don't think it is needed. The scheduler will do its job
                 //and the thread will be released sooner. Later, it will wait
                 //until the Pool reuses it. Correct me if I'm wrong
                 //but please comment the reasons, as I don't get it :)
 
                 //yield this thread so that other threads can now execute
                 //if necessary.
                 //this.yield();
 
                 //ok... add this thread back into the thread pool
                 ( (JetspeedThreadPoolService)TurbineServices
                   .getInstance()
                   .getService( ThreadPoolService.SERVICE_NAME ) )
                     .release( this );
                 
             
                 //if the runnable == null wait because it has been not been
                 //directly assigned a task.. 
                 if ( this.getRunnable() == null ) {
                
                     try {
                         this.wait();
                     } catch (InterruptedException e) {
                         //this is a normal situation.  
                         //the DaemonFactory may want to stop this thread form 
                         //sleeping and call interrupt() on this thread.
                     } catch ( Throwable t ) {
                         logger.error("Throwable",  t);
                         //continue;
                     }
 
                 }
 
             }
 
             
             if ( this.getRunnable() != null ) {
                 this.setRunning( true );
 
                 try {
                     
                     this.getRunnable().run();
 
                 } catch ( Throwable t ) {
                     logger.error( "A problem occured while trying to run your thread", t );
                 }
                     
             }
             
         }
         
     }
     
     //misc getters/setters
 
     /***
      * Set the Runnable process to execute
      *
      * @param runnable the Object to execute
      */
     public void setRunnable( Runnable runnable ) {
         this.runnable = runnable;
     }
 
     /***
      * Get the Runnable process executing
      *
      * @return the Object executed by this thread
      */
     public Runnable getRunnable() {
         return this.runnable;
     }
     
     /***
      * Test whether the thread is currently executing a process
      *
      * @return the status of this thread. If true, the thread is currently 
      * executing a Runnable process, if false it's waiting for a new process
      */
     private boolean isRunning() {
         return this.running;
     }
     
     /***
      * Set the running status of this thread.
      *
      * @return the status of this thread
      */
     private void setRunning( boolean running ) {
         this.running = running;
     }
     
     /***
      * Get the numeric identifier of this thread
      *
      * @return the identifier of the thread
      */
     public int getId() {
         return this.id;
     }
 }