org.eclipse.jetty.server.DeflaterPool Maven / Gradle / Ivy
//
// ========================================================================
// Copyright (c) 1995-2019 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package org.eclipse.jetty.server;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.zip.Deflater;
public class DeflaterPool
{
private final Queue _pool;
private final int _compressionLevel;
private final boolean _nowrap;
private final AtomicInteger _numDeflaters = new AtomicInteger(0);
private final int _capacity;
/**
* Create a Pool of {@link Deflater} instances.
*
* If given a capacity equal to zero the Deflaters will not be pooled
* and will be created on acquire and ended on release.
* If given a negative capacity equal to zero there will be no size restrictions on the DeflaterPool
*
* @param capacity maximum number of Deflaters which can be contained in the pool
* @param compressionLevel the default compression level for new Deflater objects
* @param nowrap if true then use GZIP compatible compression for all new Deflater objects
*/
public DeflaterPool(int capacity, int compressionLevel, boolean nowrap)
{
_capacity = capacity;
_compressionLevel = compressionLevel;
_nowrap = nowrap;
if (_capacity != 0)
_pool = new ConcurrentLinkedQueue<>();
else
_pool = null;
}
protected Deflater newDeflater()
{
return new Deflater(_compressionLevel, _nowrap);
}
/**
* @return Deflater taken from the pool if it is not empty or a newly created Deflater
*/
public Deflater acquire()
{
Deflater deflater;
if (_capacity == 0)
deflater = newDeflater();
else if (_capacity < 0)
{
deflater = _pool.poll();
if (deflater == null)
deflater = newDeflater();
}
else
{
deflater = _pool.poll();
if (deflater == null)
deflater = newDeflater();
else
_numDeflaters.decrementAndGet();
}
return deflater;
}
/**
* @param deflater returns this Deflater to the pool or calls deflater.end() if the pool is full.
*/
public void release(Deflater deflater)
{
if (deflater == null)
return;
if (_capacity == 0)
{
deflater.end();
return;
}
else if (_capacity < 0)
{
deflater.reset();
_pool.add(deflater);
}
else
{
while (true)
{
int d = _numDeflaters.get();
if (d >= _capacity)
{
deflater.end();
break;
}
if (_numDeflaters.compareAndSet(d, d + 1))
{
deflater.reset();
_pool.add(deflater);
break;
}
}
}
}
}