napletmonitorimpl.java~2~

移动Agent编程工具Naplet

/*
 * @<#> NapletMonitorImpl.java version 0.1, 7/1.2001
 *
 * THIS PROGRAM IS FREE SOFTWARE; YOU CAN DISTRIBUTE IT AND/OR
 * MODIFY IT UNDER THE TERMS OF THE GNU GENERAL PUBLIC LICENSE
 * AS PUBLISHED BY THE FREE SOFTWARE FOUNDATION.
 *
 * THIS PROGRAM IS DISTRIBUTED IN THE HOPE THAT IT WILL BE USEFUL,
 * BUT WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED WARRANTY OF
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. SEE THE
 * GNU GENERAL PUBLIC LICENSE FOR MORE DETAILS.
 *
 * Copyright (c) 2000 Wayne State University. All Rights Reserved.
 */
package naplet.server;

import java.util.*;
import naplet.*;

/**
 * The <code>NapletMonitorImpl</code> provides an implementation
 * of the <code>NapletMonitor</code> interface. It relies on a
 * <code>NapletThreadTable</code> to maintain the run-time information
 * of the residing alien naplets.
 *
 * @see NapletMonitor
 * @version 0.1, 7/1/2001
 * @author C. Xu, [e-mail]
 */
public class NapletMonitorImpl
    implements NapletMonitor, Runnable
{
  private static int MAX_NAPLETTHREAD_PRI = 8;
  private static NapletMonitorImpl instance = null;
  private ServerProperty property;
  private NapletThreadTable threadTable;
  /** table for server socket */
  private Hashtable nssTable = new Hashtable();
  protected NapletMonitorImpl( ServerProperty property )
  {
    this.property = property;
    threadTable = new NapletThreadTable();
  }

  public static NapletMonitorImpl getInstance( ServerProperty property )
  {
    if ( instance == null )
    {
      instance = new NapletMonitorImpl( property );
    }
    return instance;
  }

  public void join( Naplet nap )
  {
    ThreadGroup group = new ThreadGroup( nap.getNapletID().toString() );
    group.setMaxPriority( MAX_NAPLETTHREAD_PRI );

    NapletContext context = new NapletContext(
        property.getServerURN(),
        property.getNavigator(),
        property.getMessenger(),
        property.getResourceManager().getServiceProxy( nap.getNapletID() )
        );

    Thread thr = new Thread( group, new NapletThread( nap, context ) );

    threadTable.put( nap.getNapletID(), thr );

    /** record server here !!zhongxl:*/
    String svr = nap.getServer();
    String sid = nap.getServerID();
    if ( ( svr != null ) && ( sid != null ) )
    {
      nssTable.put( sid, svr );
    }
//    System.out.println("thread table:"+threadTable+",nss:"+nssTable);
    thr.start();

  }

  /**
   * locate a server according to its naplet id.
   * @param nid
   * @return
   */
  public String locate( NapletID nid )
  {
    return ( String ) nssTable.get( nid.toString() );
  }

  public void leave( NapletID nid )
  {}

  public void interrupt( NapletID nid )
  {
    Thread thr = threadTable.get( nid );
    if ( thr != null )
    {
      thr.interrupt();
    }
  }

  public void run()
  {}

  /**
   * Create a naplet thread
   */
  private class NapletThread
      implements Runnable
  {
    Naplet naplet;
    NapletContext context;
    NapletThread( Naplet naplet, NapletContext context )
    {
      this.naplet = naplet;
      this.context = context;
    }

    public void run()
    {
      naplet.init0( context );
      naplet.init();
      try
      {
        naplet.onStart();
      }
      catch ( InterruptedException ie )
      {
        naplet.onInterrupt();
      }
    }
  }

  /**
   * The <code>NapletThreadTable</code> object contains
   * a list of threads (thread group) associated with each
   * alien naplet. NapletServer manages the threads based on
   * this information.
   *
   * @version 0.0.1, 1/1/2001
   * @author C. Xu
   *
   * @see NapletServer
   */
  private class NapletThreadTable
  {
    private HashMap threadTable;
    protected NapletThreadTable()
    {
      threadTable = new HashMap();
    }

    protected void put( NapletID nid, Thread thr )
    {
      String key = nid.toString();
      threadTable.put( key, thr );
    }

    protected void remove( NapletID nid )
    {
      String key = nid.toString();
      threadTable.remove( key );
    }

    protected Thread get( NapletID nid )
    {
      String key = nid.toString();
      return ( Thread ) threadTable.get( key );
    }

    public String toString()
    {
      return threadTable.toString();
    }
  }
}