1/*
2 * Copyright (C) 2011 University of Szeged
3 * Copyright (C) 2011 Gabor Loki <loki@webkit.org>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY UNIVERSITY OF SZEGED ``AS IS'' AND ANY
16 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
18 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF SZEGED OR
19 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
20 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
22 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
23 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
25 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#include "config.h"
29
30#if ENABLE(THREADING_GENERIC)
31
32#include <wtf/NumberOfCores.h>
33#include <wtf/ParallelJobs.h>
34
35namespace WTF {
36
37Vector< RefPtr<ParallelEnvironment::ThreadPrivate> >* ParallelEnvironment::s_threadPool = 0;
38
39ParallelEnvironment::ParallelEnvironment(ThreadFunction threadFunction, size_t sizeOfParameter, int requestedJobNumber) :
40 m_threadFunction(threadFunction),
41 m_sizeOfParameter(sizeOfParameter)
42{
43 ASSERT_ARG(requestedJobNumber, requestedJobNumber >= 1);
44
45 int maxNumberOfCores = numberOfProcessorCores();
46
47 if (!requestedJobNumber || requestedJobNumber > maxNumberOfCores)
48 requestedJobNumber = static_cast<unsigned>(maxNumberOfCores);
49
50 if (!s_threadPool)
51 s_threadPool = new Vector< RefPtr<ThreadPrivate> >();
52
53 // The main thread should be also a worker.
54 int maxNumberOfNewThreads = requestedJobNumber - 1;
55
56 for (int i = 0; i < maxNumberOfCores && m_threads.size() < static_cast<unsigned>(maxNumberOfNewThreads); ++i) {
57 if (s_threadPool->size() < static_cast<unsigned>(i) + 1U)
58 s_threadPool->append(ThreadPrivate::create());
59
60 if ((*s_threadPool)[i]->tryLockFor(this))
61 m_threads.append((*s_threadPool)[i]);
62 }
63
64 m_numberOfJobs = m_threads.size() + 1;
65}
66
67void ParallelEnvironment::execute(void* parameters)
68{
69 unsigned char* currentParameter = static_cast<unsigned char*>(parameters);
70 size_t i;
71 for (i = 0; i < m_threads.size(); ++i) {
72 m_threads[i]->execute(m_threadFunction, currentParameter);
73 currentParameter += m_sizeOfParameter;
74 }
75
76 // The work for the main thread.
77 (*m_threadFunction)(currentParameter);
78
79 // Wait until all jobs are done.
80 for (i = 0; i < m_threads.size(); ++i)
81 m_threads[i]->waitForFinish();
82}
83
84bool ParallelEnvironment::ThreadPrivate::tryLockFor(ParallelEnvironment* parent)
85{
86 bool locked = m_mutex.tryLock();
87
88 if (!locked)
89 return false;
90
91 if (m_parent) {
92 m_mutex.unlock();
93 return false;
94 }
95
96 if (!m_thread) {
97 m_thread = Thread::create("Parallel worker", [this] {
98 LockHolder lock(m_mutex);
99
100 while (true) {
101 if (m_running) {
102 (*m_threadFunction)(m_parameters);
103 m_running = false;
104 m_parent = nullptr;
105 m_threadCondition.notifyOne();
106 }
107
108 m_threadCondition.wait(m_mutex);
109 }
110 });
111 }
112 m_parent = parent;
113
114 m_mutex.unlock();
115 return true;
116}
117
118void ParallelEnvironment::ThreadPrivate::execute(ThreadFunction threadFunction, void* parameters)
119{
120 LockHolder lock(m_mutex);
121
122 m_threadFunction = threadFunction;
123 m_parameters = parameters;
124 m_running = true;
125 m_threadCondition.notifyOne();
126}
127
128void ParallelEnvironment::ThreadPrivate::waitForFinish()
129{
130 LockHolder lock(m_mutex);
131
132 while (m_running)
133 m_threadCondition.wait(m_mutex);
134}
135
136} // namespace WTF
137#endif // ENABLE(THREADING_GENERIC)
138