1/*
2 * Copyright (C) 2017 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include <wtf/ReadWriteLock.h>
28
29#include <wtf/Locker.h>
30
31namespace WTF {
32
33void ReadWriteLock::readLock()
34{
35 auto locker = holdLock(m_lock);
36 while (m_isWriteLocked || m_numWaitingWriters)
37 m_cond.wait(m_lock);
38 m_numReaders++;
39}
40
41void ReadWriteLock::readUnlock()
42{
43 auto locker = holdLock(m_lock);
44 m_numReaders--;
45 if (!m_numReaders)
46 m_cond.notifyAll();
47}
48
49void ReadWriteLock::writeLock()
50{
51 auto locker = holdLock(m_lock);
52 while (m_isWriteLocked || m_numReaders) {
53 m_numWaitingWriters++;
54 m_cond.wait(m_lock);
55 m_numWaitingWriters--;
56 }
57 m_isWriteLocked = true;
58}
59
60void ReadWriteLock::writeUnlock()
61{
62 auto locker = holdLock(m_lock);
63 m_isWriteLocked = false;
64 m_cond.notifyAll();
65}
66
67} // namespace WTF
68
69