1/*
2 * Copyright (C) 2013, 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 "DeferGC.h"
29#include <wtf/Lock.h>
30#include <wtf/NoLock.h>
31#include <wtf/Optional.h>
32
33namespace JSC {
34
35using ConcurrentJSLock = Lock;
36using ConcurrentJSLockerImpl = LockHolder;
37
38static_assert(sizeof(ConcurrentJSLock) == 1, "Regardless of status of concurrent JS flag, size of ConurrentJSLock is always one byte.");
39
40class ConcurrentJSLockerBase : public AbstractLocker {
41 WTF_MAKE_NONCOPYABLE(ConcurrentJSLockerBase);
42public:
43 explicit ConcurrentJSLockerBase(ConcurrentJSLock& lockable)
44 : m_locker(&lockable)
45 {
46 }
47 explicit ConcurrentJSLockerBase(ConcurrentJSLock* lockable)
48 : m_locker(lockable)
49 {
50 }
51
52 explicit ConcurrentJSLockerBase(NoLockingNecessaryTag)
53 : m_locker(NoLockingNecessary)
54 {
55 }
56
57 ~ConcurrentJSLockerBase()
58 {
59 }
60
61 void unlockEarly()
62 {
63 m_locker.unlockEarly();
64 }
65
66private:
67 ConcurrentJSLockerImpl m_locker;
68};
69
70class GCSafeConcurrentJSLocker : public ConcurrentJSLockerBase {
71public:
72 GCSafeConcurrentJSLocker(ConcurrentJSLock& lockable, Heap& heap)
73 : ConcurrentJSLockerBase(lockable)
74 , m_deferGC(heap)
75 {
76 }
77
78 GCSafeConcurrentJSLocker(ConcurrentJSLock* lockable, Heap& heap)
79 : ConcurrentJSLockerBase(lockable)
80 , m_deferGC(heap)
81 {
82 }
83
84 ~GCSafeConcurrentJSLocker()
85 {
86 // We have to unlock early due to the destruction order of base
87 // vs. derived classes. If we didn't, then we would destroy the
88 // DeferGC object before unlocking the lock which could cause a GC
89 // and resulting deadlock.
90 unlockEarly();
91 }
92
93private:
94 DeferGC m_deferGC;
95};
96
97class ConcurrentJSLocker : public ConcurrentJSLockerBase {
98public:
99 ConcurrentJSLocker(ConcurrentJSLock& lockable)
100 : ConcurrentJSLockerBase(lockable)
101#if !defined(NDEBUG)
102 , m_disallowGC(std::in_place)
103#endif
104 {
105 }
106
107 ConcurrentJSLocker(ConcurrentJSLock* lockable)
108 : ConcurrentJSLockerBase(lockable)
109#if !defined(NDEBUG)
110 , m_disallowGC(std::in_place)
111#endif
112 {
113 }
114
115 ConcurrentJSLocker(NoLockingNecessaryTag)
116 : ConcurrentJSLockerBase(NoLockingNecessary)
117#if !defined(NDEBUG)
118 , m_disallowGC(WTF::nullopt)
119#endif
120 {
121 }
122
123 ConcurrentJSLocker(int) = delete;
124
125#if !defined(NDEBUG)
126private:
127 Optional<DisallowGC> m_disallowGC;
128#endif
129};
130
131} // namespace JSC
132