1/*
2 * Copyright (C) 2010 Apple Inc. All rights reserved.
3 * Copyright (C) 2017 Sony Interactive Entertainment Inc.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
15 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
16 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
18 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
19 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
20 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
21 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
22 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
23 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
24 * THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include "config.h"
28#include <wtf/WorkQueue.h>
29
30#include <mutex>
31#include <wtf/Condition.h>
32#include <wtf/Deque.h>
33#include <wtf/Function.h>
34#include <wtf/Lock.h>
35#include <wtf/NeverDestroyed.h>
36#include <wtf/NumberOfCores.h>
37#include <wtf/Ref.h>
38#include <wtf/Threading.h>
39#include <wtf/text/StringConcatenateNumbers.h>
40
41namespace WTF {
42
43Ref<WorkQueue> WorkQueue::create(const char* name, Type type, QOS qos)
44{
45 return adoptRef(*new WorkQueue(name, type, qos));
46}
47
48WorkQueue::WorkQueue(const char* name, Type type, QOS qos)
49{
50 platformInitialize(name, type, qos);
51}
52
53WorkQueue::~WorkQueue()
54{
55 platformInvalidate();
56}
57
58#if !PLATFORM(COCOA)
59void WorkQueue::concurrentApply(size_t iterations, WTF::Function<void (size_t index)>&& function)
60{
61 if (!iterations)
62 return;
63
64 if (iterations == 1) {
65 function(0);
66 return;
67 }
68
69 class ThreadPool {
70 public:
71 ThreadPool()
72 {
73 // We don't need a thread for the current core.
74 unsigned threadCount = numberOfProcessorCores() - 1;
75
76 m_workers.reserveInitialCapacity(threadCount);
77 for (unsigned i = 0; i < threadCount; ++i) {
78 m_workers.append(Thread::create("ThreadPool Worker", [this] {
79 threadBody();
80 }));
81 }
82 }
83
84 size_t workerCount() const { return m_workers.size(); }
85
86 void dispatch(const WTF::Function<void ()>* function)
87 {
88 LockHolder holder(m_lock);
89
90 m_queue.append(function);
91 m_condition.notifyOne();
92 }
93
94 private:
95 NO_RETURN void threadBody()
96 {
97 while (true) {
98 const WTF::Function<void ()>* function;
99
100 {
101 LockHolder holder(m_lock);
102
103 m_condition.wait(m_lock, [this] {
104 return !m_queue.isEmpty();
105 });
106
107 function = m_queue.takeFirst();
108 }
109
110 (*function)();
111 }
112 }
113
114 Lock m_lock;
115 Condition m_condition;
116 Deque<const WTF::Function<void ()>*> m_queue;
117
118 Vector<Ref<Thread>> m_workers;
119 };
120
121 static LazyNeverDestroyed<ThreadPool> threadPool;
122 static std::once_flag onceFlag;
123 std::call_once(onceFlag, [] {
124 threadPool.construct();
125 });
126
127 // Cap the worker count to the number of iterations (excluding this thread)
128 const size_t workerCount = std::min(iterations - 1, threadPool->workerCount());
129
130 std::atomic<size_t> currentIndex(0);
131 std::atomic<size_t> activeThreads(workerCount + 1);
132
133 Condition condition;
134 Lock lock;
135
136 WTF::Function<void ()> applier = [&, function = WTFMove(function)] {
137 size_t index;
138
139 // Call the function for as long as there are iterations left.
140 while ((index = currentIndex++) < iterations)
141 function(index);
142
143 // If there are no active threads left, signal the caller.
144 if (!--activeThreads) {
145 LockHolder holder(lock);
146 condition.notifyOne();
147 }
148 };
149
150 for (size_t i = 0; i < workerCount; ++i)
151 threadPool->dispatch(&applier);
152 applier();
153
154 LockHolder holder(lock);
155 condition.wait(lock, [&] { return !activeThreads; });
156}
157#endif
158
159}
160