/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.excalibur.mpool;
import org.apache.avalon.framework.activity.Disposable;
import org.apache.avalon.framework.activity.Initializable;
import org.apache.commons.collections.BoundedFifoBuffer;
import org.apache.commons.collections.Buffer;
import org.apache.commons.collections.BufferUnderflowException;
/**
* This is an <code>Pool</code> that caches Poolable objects for reuse.
* Please note that this pool offers no resource limiting whatsoever.
*
* @author <a href="mailto:dev@avalon.apache.org">Avalon Development Team</a>
* @version CVS $Revision: 1.4 $ $Date: 2004/02/28 11:47:34 $
* @since 4.1
*/
public final class BlockingFixedSizePool
implements Pool, Disposable, Initializable
{
private boolean m_disposed = false;
private final Buffer m_buffer;
private final ObjectFactory m_factory;
private final long m_timeout;
private final int m_maxSize;
/** The semaphor we synchronize on */
protected final Object m_semaphore = new Object();
public BlockingFixedSizePool( ObjectFactory factory, int size )
throws Exception
{
this( factory, size, 1000 );
}
public BlockingFixedSizePool( ObjectFactory factory, int size, long timeout )
throws Exception
{
m_timeout = ( timeout < 1 ) ? 0 : timeout;
m_buffer = new BoundedFifoBuffer( size );
m_maxSize = size;
m_factory = factory;
}
public void initialize()
throws Exception
{
for( int i = 0; i < m_maxSize; i++ )
{
m_buffer.add( newInstance() );
}
}
public Object acquire()
{
if( m_disposed )
{
throw new IllegalStateException( "Cannot get an object from a disposed pool" );
}
Object object = null;
synchronized( m_semaphore )
{
if( m_buffer.isEmpty() )
{
long blockStart = System.currentTimeMillis();
if( m_timeout > 0 )
{
long blockWait = m_timeout;
do
{
try
{
m_semaphore.wait( blockWait );
}
catch( InterruptedException ie )
{
}
if( m_disposed )
{
throw new IllegalStateException( "Pool disposed of while waiting for resources to free up" );
}
if( m_buffer.isEmpty() )
{
blockWait = m_timeout -
( System.currentTimeMillis() - blockStart );
}
} while( m_buffer.isEmpty() && blockWait > 0 );
}
else
{
do
{
try
{
m_semaphore.wait();
}
catch( InterruptedException ie )
{
}
if( m_disposed )
{
throw new IllegalStateException( "Pool disposed of while waiting for resources to free up" );
}
} while( m_buffer.isEmpty() );
}
}
try
{
object = m_buffer.remove();
}
catch( BufferUnderflowException bufe )
{
// ignore exception and leave object as null
}
}
if( object == null )
{
throw new IllegalStateException( "Timeout exceeded without acquiring resource." );
}
return object;
}
public void release( Object object )
{
synchronized( m_semaphore )
{
if( m_disposed )
{
try
{
m_factory.dispose( object );
}
catch( Exception e )
{
// We should never get here, but ignore the exception if it happens
}
}
else
{
if( m_buffer.size() < m_maxSize )
{
m_buffer.add( PoolUtil.recycle( object ) );
m_semaphore.notify();
}
else
{
try
{
m_factory.dispose( object );
}
catch( Exception e )
{
// We should never get here, but ignore the exception if it happens
}
}
}
}
}
public Object newInstance()
throws Exception
{
return m_factory.newInstance();
}
public void dispose()
{
m_disposed = true;
synchronized( m_semaphore )
{
while( !m_buffer.isEmpty() )
{
try
{
m_factory.dispose( m_buffer.remove() );
}
catch( Exception e )
{
// We should never get here, but ignore the exception if it happens
}
}
m_semaphore.notifyAll();
}
}
}