1/*
2 * Copyright (c) 2015, 2016, 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 */
25package jdk.incubator.http.internal.common;
26
27import java.nio.ByteBuffer;
28import 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 */
38public 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}
61