1/*
2 * Copyright (C) 2015 Igalia S.L
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19#pragma once
20
21#include <functional>
22#include <wtf/Atomics.h>
23#include <wtf/Lock.h>
24#include <wtf/MainThread.h>
25#include <wtf/RunLoop.h>
26#include <wtf/ThreadSafeRefCounted.h>
27
28namespace WebCore {
29
30template <typename T>
31class MainThreadNotifier final : public ThreadSafeRefCounted<MainThreadNotifier<T>> {
32public:
33 static Ref<MainThreadNotifier> create()
34 {
35 return adoptRef(*new MainThreadNotifier());
36 }
37
38 ~MainThreadNotifier()
39 {
40 ASSERT(!m_isValid.load());
41 }
42
43 bool isValid() const { return m_isValid.load(); }
44
45 template<typename F>
46 void notify(T notificationType, F&& callbackFunctor)
47 {
48 ASSERT(m_isValid.load());
49 // Assert that there is only one bit on at a time.
50 ASSERT(!(static_cast<int>(notificationType) & (static_cast<int>(notificationType) - 1)));
51 if (isMainThread()) {
52 removePendingNotification(notificationType);
53 callbackFunctor();
54 return;
55 }
56
57 if (!addPendingNotification(notificationType))
58 return;
59
60 RunLoop::main().dispatch([this, protectedThis = makeRef(*this), notificationType, callback = WTF::Function<void()>(WTFMove(callbackFunctor))] {
61 if (!m_isValid.load())
62 return;
63 if (removePendingNotification(notificationType))
64 callback();
65 });
66 }
67
68 template<typename F>
69 void notifyAndWait(T notificationType, F&& callbackFunctor)
70 {
71 Lock mutex;
72 Condition condition;
73
74 notify(notificationType, [functor = WTFMove(callbackFunctor), &condition, &mutex] {
75 functor();
76 LockHolder holder(mutex);
77 condition.notifyOne();
78 });
79
80 if (!isMainThread()) {
81 LockHolder holder(mutex);
82 condition.wait(mutex);
83 }
84 }
85
86 void cancelPendingNotifications(unsigned mask = 0)
87 {
88 ASSERT(m_isValid.load());
89 LockHolder locker(m_pendingNotificationsLock);
90 if (mask)
91 m_pendingNotifications &= ~mask;
92 else
93 m_pendingNotifications = 0;
94 }
95
96 void invalidate()
97 {
98 ASSERT(m_isValid.load());
99 m_isValid.store(false);
100 }
101
102private:
103 MainThreadNotifier()
104 {
105 m_isValid.store(true);
106 }
107
108 bool addPendingNotification(T notificationType)
109 {
110 LockHolder locker(m_pendingNotificationsLock);
111 if (notificationType & m_pendingNotifications)
112 return false;
113 m_pendingNotifications |= notificationType;
114 return true;
115 }
116
117 bool removePendingNotification(T notificationType)
118 {
119 LockHolder locker(m_pendingNotificationsLock);
120 if (notificationType & m_pendingNotifications) {
121 m_pendingNotifications &= ~notificationType;
122 return true;
123 }
124 return false;
125 }
126
127 Lock m_pendingNotificationsLock;
128 unsigned m_pendingNotifications { 0 };
129 Atomic<bool> m_isValid;
130};
131
132} // namespace WebCore
133
134