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. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include <wtf/CrossThreadTaskHandler.h>
28
29namespace WTF {
30
31CrossThreadTaskHandler::CrossThreadTaskHandler(const char* threadName)
32{
33 ASSERT(isMainThread());
34 Locker<Lock> locker(m_taskThreadCreationLock);
35 Thread::create(threadName, [this] {
36 taskRunLoop();
37 })->detach();
38}
39
40CrossThreadTaskHandler::~CrossThreadTaskHandler()
41{
42 ASSERT(isMainThread());
43}
44
45void CrossThreadTaskHandler::postTask(CrossThreadTask&& task)
46{
47 m_taskQueue.append(WTFMove(task));
48}
49
50void CrossThreadTaskHandler::postTaskReply(CrossThreadTask&& task)
51{
52 m_taskReplyQueue.append(WTFMove(task));
53
54 Locker<Lock> locker(m_mainThreadReplyLock);
55 if (m_mainThreadReplyScheduled)
56 return;
57
58 m_mainThreadReplyScheduled = true;
59 callOnMainThread([this] {
60 handleTaskRepliesOnMainThread();
61 });
62}
63
64void CrossThreadTaskHandler::taskRunLoop()
65{
66 ASSERT(!isMainThread());
67 {
68 Locker<Lock> locker(m_taskThreadCreationLock);
69 }
70
71 while (!m_taskQueue.isKilled()) {
72 m_taskQueue.waitForMessage().performTask();
73
74 Locker<Lock> shouldSuspendLocker(m_shouldSuspendLock);
75 while (m_shouldSuspend) {
76 m_suspendedLock.lock();
77 if (!m_suspended) {
78 m_suspended = true;
79 m_suspendedCondition.notifyOne();
80 }
81 m_suspendedLock.unlock();
82 m_shouldSuspendCondition.wait(m_shouldSuspendLock);
83 }
84 }
85}
86
87void CrossThreadTaskHandler::handleTaskRepliesOnMainThread()
88{
89 {
90 Locker<Lock> locker(m_mainThreadReplyLock);
91 m_mainThreadReplyScheduled = false;
92 }
93
94 while (auto task = m_taskReplyQueue.tryGetMessage())
95 task->performTask();
96}
97
98void CrossThreadTaskHandler::suspendAndWait()
99{
100 ASSERT(isMainThread());
101 {
102 Locker<Lock> locker(m_shouldSuspendLock);
103 m_shouldSuspend = true;
104 }
105
106 // Post an empty task to ensure database thread knows m_shouldSuspend and sets m_suspended.
107 postTask(CrossThreadTask([]() { }));
108
109 Locker<Lock> locker(m_suspendedLock);
110 while (!m_suspended)
111 m_suspendedCondition.wait(m_suspendedLock);
112}
113
114void CrossThreadTaskHandler::resume()
115{
116 ASSERT(isMainThread());
117 Locker<Lock> locker(m_shouldSuspendLock);
118 if (m_shouldSuspend) {
119 m_suspendedLock.lock();
120 if (m_suspended)
121 m_suspended = false;
122 m_suspendedLock.unlock();
123 m_shouldSuspend = false;
124 m_shouldSuspendCondition.notifyOne();
125 }
126}
127
128} // namespace WTF
129