/*
 * Copyright (C) 2004-2005  exedio GmbH (www.exedio.com)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package com.exedio.cope;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Iterator;

import com.exedio.cope.util.ConnectionPoolInfo;
import com.exedio.cope.util.PoolCounter;
import com.exedio.dsmf.ConnectionProvider;

final class ConnectionPool implements ConnectionProvider
{
	// TODO: allow changing pool size
	// TODO: gather pool effectivity statistics
	// TODO: use a ring buffer instead of a stack
	//       to avoid connections at the bottom of the stack
	//       staying idle for a very long time and possibly
	//       running into some idle timeout implemented by the
	//       jdbc driver or the database itself.
	// TODO: implement idle timout
	//       ensure, that idle connections in the pool do
	//       not stay idle for a indefinite time,
	//       but are closed after a certain time to avoid
	//       running into some idle timeout implemented by the
	//       jdbc driver or the database itself.
	//       maybe then no ring buffer is needed.
	
	private final Connection[] idle;
	private int idleCount = 0;
	private int activeCount = 0;
	private final Object lock = new Object();

	private final String url;
	private final String user;
	private final String password;
	
	private final PoolCounter counter;

	ConnectionPool(final Properties properties)
	{
		this.url = properties.getDatabaseUrl();
		this.user = properties.getDatabaseUser();
		this.password = properties.getDatabasePassword();
		final int idleLength = properties.getConnectionPoolIdleLimit();
		this.idle = idleLength>0 ? new Connection[idleLength] : null;
		
		// TODO: make this customizable and disableable
		this.counter = new PoolCounter(new int[]{0,1,2,3,4,5,6,7,8,9,10,12,15,16,18,20,25,30,35,40,45,50,60,70,80,90,100,120,140,160,180,200,250,300,350,400,450,500,600,700,800,900,1000});
	}

	public final Connection getConnection() throws SQLException
	{
		counter.get();

		if(idle!=null)
		{
			synchronized(lock)
			{
				activeCount++;
				
				if(idleCount>0)
				{
					//System.out.println("connection pool: fetch "+(size-1));
					final Connection result = idle[--idleCount];
					idle[idleCount] = null; // do not reference active connections
					return result;
				}
			}
		}
		else
			activeCount++;
		//System.out.println("connection pool: CREATE");

		// Important to do this outside the synchronized block!
		return  DriverManager.getConnection(url, user, password);
	}

	/**
	 * TODO: If we want to implement changing connection parameters on-the-fly
	 * somewhere in the future, it's important, that client return connections
	 * to exactly the same instance of ConnectionPool.
	 */
	public final void putConnection(final Connection connection) throws SQLException
	{
		if(connection==null)
			throw new NullPointerException();

		counter.put();
		
		if(idle!=null)
		{
			synchronized(lock)
			{
				activeCount--;
	
				if(idleCount<idle.length)
				{
					//System.out.println("connection pool: store "+size);
					idle[idleCount++] = connection;
					return;
				}
			}
		}
		else
			activeCount--;
		
		//System.out.println("connection pool: CLOSE ");

		// Important to do this outside the synchronized block!
		connection.close();
	}
	
	final void flush()
	{
		if(idle!=null)
		{
			// make a copy of idle to avoid closing idle connections
			// inside the synchronized block
			final ArrayList copyOfIdle = new ArrayList(idle.length);
	
			synchronized(lock)
			{
				if(idleCount==0)
					return;
	
				//System.out.println("connection pool: FLUSH "+size);
				for(int i = 0; i<idleCount; i++)
				{
					copyOfIdle.add(idle[i]);
					idle[i] = null; // do not reference closed connections
				}
				idleCount = 0;
			}
			
			try
			{
				for(Iterator i = copyOfIdle.iterator(); i.hasNext(); )
					((Connection)i.next()).close();
			}
			catch(SQLException e)
			{
				throw new RuntimeException(e);
			}
		}

		if(activeCount!=0)
			throw new RuntimeException("still "+activeCount+" connections active");
	}
	
	final ConnectionPoolInfo getInfo()
	{
		return new ConnectionPoolInfo(idleCount, activeCount, new PoolCounter(counter));
	}

}

@@ -2317,21 +2317,20 @@
 nt idleL
-ength
+imit
  = prope
@@ -2384,21 +2384,20 @@
  = idleL
-ength
+imit
 %3E0 ? new
@@ -2413,21 +2413,20 @@
 on%5BidleL
-ength
+imit
 %5D : null

rename idleLength to idleLimit