ConnectionRunnerPool.java

/* gnu.java.rmi.server.ConnectionRunnerPool
   Copyright (C) 2002, 2004, 2005 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath 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.

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along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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this exception to your version of the library, but you are not
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package gnu.java.rmi.server;

import java.util.ArrayList;
import java.util.Arrays;

//Should I generalize this class?

class ConnectionRunnerPool
{

  public static
    class ConnectionRunner extends Thread{
      private UnicastConnection conn;
      private volatile boolean exiting = false;

      public ConnectionRunner(ThreadGroup group, String id){
        super(group, id);
      }

      public synchronized void run(){
        while(!exiting){
          if(conn == null)
            try{
              wait();
            }catch(InterruptedException e){
              continue;
            }
          else{
            conn.run();
            conn = null;
            synchronized(ConnectionRunnerPool.class){
              freelist.add(this);
              if(freelist.size() == 1)
                ConnectionRunnerPool.class.notifyAll();
            }
          }
        }
      }

      public synchronized void dispatch(UnicastConnection conn){
        this.conn = conn;
        notify();
      }

      void exit(){
        exiting = true;
        if(conn != null)
          try{
            join(500);
          }catch(InterruptedException e){}
        interrupt();
      }

    }

  // Should this value equal to number of CPU?
  private static int size = 5;
  private static int max_size = 10;

  // Package-private to avoid a trampoline.
  static ArrayList freelist;

  private static ThreadGroup group = new ThreadGroup("pool");

  static {
    ConnectionRunner[] pools = new ConnectionRunner[size];
    for(int i = 0; i < pools.length; i++){
      pools[i] = new ConnectionRunner(group, Integer.toString(i));
      pools[i].setContextClassLoader(Thread.currentThread().getContextClassLoader());
      pools[i].start();
    }
    freelist = new ArrayList(Arrays.asList(pools));
  }

  public static void setSize(int size_){
    size = size_;
  }

  public static void setMaxSize(int size){
    max_size = size;
  }

  private static synchronized ConnectionRunner getConnectionRunner()
  {
    if(freelist.size() == 0){
      if(size < max_size){
        ++size;
        ConnectionRunner a = new ConnectionRunner(group, Integer.toString(size));
        a.start();
        freelist.add(a);
      }else
        while(freelist.size() == 0)
          try{
            ConnectionRunnerPool.class.wait();
          }catch(InterruptedException e){}
    }

    // always let the first in pool most busy or other scheduling plan??
    ConnectionRunner a = (ConnectionRunner)freelist.get(0);
    freelist.remove(a);
    return a;
  }

  public static void dispatchConnection(UnicastConnection conn)
  {
    ConnectionRunner r = getConnectionRunner();
    r.dispatch(conn);
  }

  public static void exit()
  {
    Thread[] list = new Thread[group.activeCount()];
    group.enumerate(list);
    for(int i = 0; i < list.length; i++)
      ((ConnectionRunner)list[i]).exit();
  }

}