// ========================================================================
// $Id: ByteArrayPool.java,v 1.9 2004/05/09 20:32:49 gregwilkins Exp $
// Copyright 2002-2004 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// Licensed 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.mortbay.util;
import java.util.concurrent.atomic.AtomicInteger;
/* ------------------------------------------------------------ */
/** Byte Array Pool
* Simple pool for recycling byte arrays of a fixed size.
*
* @version $Id: ByteArrayPool.java,v 1.9 2004/05/09 20:32:49 gregwilkins Exp $
* @author Greg Wilkins (gregw)
*/
public class ByteArrayPool
{
public static final int __POOL_SIZE=
Integer.getInteger("org.mortbay.util.ByteArrayPool.pool_size",8).intValue();
public static final ThreadLocal<byte[][]> __pools = new BAThreadLocal();
public static final AtomicInteger __slot = new AtomicInteger();
/* ------------------------------------------------------------ */
/** Get a byte array from the pool of known size.
* @param size Size of the byte array.
* @return Byte array of known size.
*/
public static byte[] getByteArray(int size)
{
byte[][] pool = __pools.get();
boolean full=true;
for (int i=pool.length;i-->0;)
{
if (pool[i]!=null && pool[i].length==size)
{
byte[]b = pool[i];
pool[i]=null;
return b;
}
else
full=false;
}
if (full)
for (int i=pool.length;i-->0;)
pool[i]=null;
return new byte[size];
}
/* ------------------------------------------------------------ */
public static byte[] getByteArrayAtLeast(int minSize)
{
byte[][] pool = __pools.get();
for (int i=pool.length;i-->0;)
{
if (pool[i]!=null && pool[i].length>=minSize)
{
byte[]b = pool[i];
pool[i]=null;
return b;
}
}
return new byte[minSize];
}
/* ------------------------------------------------------------ */
public static void returnByteArray(final byte[] b)
{
if (b==null)
return;
byte[][] pool = __pools.get();
for (int i=pool.length;i-->0;)
{
if (pool[i]==null)
{
pool[i]=b;
return;
}
}
// slot.
int s = __slot.getAndIncrement();
if (s<0)s=-s;
pool[s%pool.length]=b;
}
/* ------------------------------------------------------------ */
/* ------------------------------------------------------------ */
private static final class BAThreadLocal extends ThreadLocal<byte[][]>
{
@Override
protected byte[][] initialValue()
{
return new byte[__POOL_SIZE][];
}
}
}