runnablethread.java

来自「jetspeed源代码」· Java 代码 · 共 224 行

/*
 * 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:[e-mail]">Kevin A. Burton</a>
 * @author <a href="mailto:[e-mail]">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;
    }
}