1/*
2 * Copyright (C) 2017 Yusuke Suzuki <utatane.tea@gmail.com>.
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#include "config.h"
27#include <wtf/WorkerPool.h>
28
29#include <wtf/NeverDestroyed.h>
30
31namespace WTF {
32
33class WorkerPool::Worker final : public AutomaticThread {
34public:
35 friend class WorkerPool;
36
37 Worker(const AbstractLocker& locker, WorkerPool& pool, Box<Lock> lock, Ref<AutomaticThreadCondition>&& condition, Seconds timeout)
38 : AutomaticThread(locker, lock, WTFMove(condition), timeout)
39 , m_pool(pool)
40 {
41 }
42
43 PollResult poll(const AbstractLocker&) final
44 {
45 if (m_pool.m_tasks.isEmpty())
46 return PollResult::Wait;
47 m_task = m_pool.m_tasks.takeFirst();
48 if (!m_task)
49 return PollResult::Stop;
50 return PollResult::Work;
51 }
52
53 WorkResult work() final
54 {
55 m_task();
56 m_task = nullptr;
57 return WorkResult::Continue;
58 }
59
60 void threadDidStart() final
61 {
62 LockHolder locker(*m_pool.m_lock);
63 m_pool.m_numberOfActiveWorkers++;
64 }
65
66 void threadIsStopping(const AbstractLocker&) final
67 {
68 m_pool.m_numberOfActiveWorkers--;
69 }
70
71 bool shouldSleep(const AbstractLocker& locker) final
72 {
73 return m_pool.shouldSleep(locker);
74 }
75
76 const char* name() const override
77 {
78 return m_pool.name();
79 }
80
81private:
82 WorkerPool& m_pool;
83 Function<void()> m_task;
84};
85
86WorkerPool::WorkerPool(ASCIILiteral name, unsigned numberOfWorkers, Seconds timeout)
87 : m_lock(Box<Lock>::create())
88 , m_condition(AutomaticThreadCondition::create())
89 , m_timeout(timeout)
90 , m_name(name)
91{
92 LockHolder locker(*m_lock);
93 for (unsigned i = 0; i < numberOfWorkers; ++i)
94 m_workers.append(adoptRef(*new Worker(locker, *this, m_lock, m_condition.copyRef(), timeout)));
95}
96
97WorkerPool::~WorkerPool()
98{
99 {
100 LockHolder locker(*m_lock);
101 for (unsigned i = m_workers.size(); i--;)
102 m_tasks.append(nullptr); // Use null task to indicate that we want the thread to terminate.
103 m_condition->notifyAll(locker);
104 }
105 for (auto& worker : m_workers)
106 worker->join();
107 ASSERT(!m_numberOfActiveWorkers);
108}
109
110bool WorkerPool::shouldSleep(const AbstractLocker&)
111{
112 if (m_timeout > 0_s && std::isinf(m_timeout))
113 return false;
114
115 MonotonicTime currentTime = MonotonicTime::now();
116 if (std::isnan(m_lastTimeoutTime) || (currentTime >= (m_lastTimeoutTime + m_timeout))) {
117 m_lastTimeoutTime = currentTime;
118 return true;
119 }
120 return false;
121}
122
123void WorkerPool::postTask(Function<void()>&& task)
124{
125 LockHolder locker(*m_lock);
126 m_tasks.append(WTFMove(task));
127 m_condition->notifyOne(locker);
128}
129
130}
131