1/*
2 * Copyright (C) 2016 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#pragma once
27
28#include <wtf/Lock.h>
29#include <wtf/Threading.h>
30
31namespace WTF {
32
33template<typename LockType>
34class RecursiveLockAdapter {
35public:
36 RecursiveLockAdapter() = default;
37
38 void lock()
39 {
40 Thread& me = Thread::current();
41 if (&me == m_owner) {
42 m_recursionCount++;
43 return;
44 }
45
46 m_lock.lock();
47 ASSERT(!m_owner);
48 ASSERT(!m_recursionCount);
49 m_owner = &me;
50 m_recursionCount = 1;
51 }
52
53 void unlock()
54 {
55 if (--m_recursionCount)
56 return;
57 m_owner = nullptr;
58 m_lock.unlock();
59 }
60
61 bool tryLock()
62 {
63 Thread& me = Thread::current();
64 if (&me == m_owner) {
65 m_recursionCount++;
66 return true;
67 }
68
69 if (!m_lock.tryLock())
70 return false;
71
72 ASSERT(!m_owner);
73 ASSERT(!m_recursionCount);
74 m_owner = &me;
75 m_recursionCount = 1;
76 return true;
77 }
78
79 bool isLocked() const
80 {
81 return m_lock.isLocked();
82 }
83
84private:
85 Thread* m_owner { nullptr }; // Use Thread* instead of RefPtr<Thread> since m_owner thread is always alive while m_onwer is set.
86 unsigned m_recursionCount { 0 };
87 LockType m_lock;
88};
89
90using RecursiveLock = RecursiveLockAdapter<Lock>;
91
92} // namespace WTF
93
94using WTF::RecursiveLock;
95