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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permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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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, new Integer(i).toString());
      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, new Integer(size).toString());
	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();
  }
  
}