1 /*
   2  * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package jdk.incubator.http.internal.common;
  26 
  27 import java.nio.ByteBuffer;
  28 import java.util.concurrent.ConcurrentLinkedQueue;
  29 
  30 /**
  31  * The class provides reuse of ByteBuffers.
  32  * It is supposed that all requested buffers have the same size for a long period of time.
  33  * That is why there is no any logic splitting buffers into different buckets (by size). It's unnecessary.
  34  *
  35  * At the same moment it is allowed to change requested buffers size (all smaller buffers will be discarded).
  36  * It may be needed for example, if after rehandshaking netPacketBufferSize was changed.
  37  */
  38 public class ByteBufferPool {
  39 
  40     private final java.util.Queue<ByteBuffer> pool = new ConcurrentLinkedQueue<>();
  41 
  42     public ByteBufferPool() {
  43     }
  44 
  45     public ByteBufferReference get(int size) {
  46         ByteBuffer buffer;
  47         while ((buffer = pool.poll()) != null) {
  48             if (buffer.capacity() >= size) {
  49                 return ByteBufferReference.of(buffer, this);
  50             }
  51         }
  52         return ByteBufferReference.of(ByteBuffer.allocate(size), this);
  53     }
  54 
  55     public void release(ByteBuffer buffer) {
  56         buffer.clear();
  57         pool.offer(buffer);
  58     }
  59 
  60 }