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/*
* Copyright (C) 2011 University of Szeged
* Copyright (C) 2011 Gabor Loki <loki@webkit.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY UNIVERSITY OF SZEGED ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF SZEGED OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include <wtf/ParallelJobsGeneric.h>
#if ENABLE(THREADING_GENERIC)
#include <wtf/NumberOfCores.h>
namespace WTF {
Vector< RefPtr<ParallelEnvironment::ThreadPrivate> >* ParallelEnvironment::s_threadPool = nullptr;
ParallelEnvironment::ParallelEnvironment(ThreadFunction threadFunction, size_t sizeOfParameter, int requestedJobNumber) :
m_threadFunction(threadFunction),
m_sizeOfParameter(sizeOfParameter)
{
ASSERT_ARG(requestedJobNumber, requestedJobNumber >= 1);
int maxNumberOfCores = numberOfProcessorCores();
if (!requestedJobNumber || requestedJobNumber > maxNumberOfCores)
requestedJobNumber = static_cast<unsigned>(maxNumberOfCores);
if (!s_threadPool)
s_threadPool = new Vector< RefPtr<ThreadPrivate> >();
// The main thread should be also a worker.
int maxNumberOfNewThreads = requestedJobNumber - 1;
for (int i = 0; i < maxNumberOfCores && m_threads.size() < static_cast<unsigned>(maxNumberOfNewThreads); ++i) {
if (s_threadPool->size() < static_cast<unsigned>(i) + 1U)
s_threadPool->append(ThreadPrivate::create());
if ((*s_threadPool)[i]->tryLockFor(this))
m_threads.append((*s_threadPool)[i]);
}
m_numberOfJobs = m_threads.size() + 1;
}
void ParallelEnvironment::execute(void* parameters)
{
WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
unsigned char* currentParameter = static_cast<unsigned char*>(parameters);
WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
size_t i;
for (i = 0; i < m_threads.size(); ++i) {
m_threads[i]->execute(m_threadFunction, currentParameter);
currentParameter += m_sizeOfParameter;
}
// The work for the main thread.
(*m_threadFunction)(currentParameter);
// Wait until all jobs are done.
for (i = 0; i < m_threads.size(); ++i)
m_threads[i]->waitForFinish();
}
bool ParallelEnvironment::ThreadPrivate::tryLockFor(ParallelEnvironment* parent)
{
bool locked = m_lock.tryLock();
if (!locked)
return false;
if (m_parent) {
m_lock.unlock();
return false;
}
if (!m_thread) {
m_thread = Thread::create("Parallel worker"_s, [this] {
Locker lock { m_lock };
while (true) {
if (m_running) {
(*m_threadFunction)(m_parameters);
m_running = false;
m_parent = nullptr;
m_threadCondition.notifyOne();
}
m_threadCondition.wait(m_lock);
}
});
}
m_parent = parent;
m_lock.unlock();
return true;
}
void ParallelEnvironment::ThreadPrivate::execute(ThreadFunction threadFunction, void* parameters)
{
Locker lock { m_lock };
m_threadFunction = threadFunction;
m_parameters = parameters;
m_running = true;
m_threadCondition.notifyOne();
}
void ParallelEnvironment::ThreadPrivate::waitForFinish()
{
Locker lock { m_lock };
while (m_running)
m_threadCondition.wait(m_lock);
}
} // namespace WTF
#endif // ENABLE(THREADING_GENERIC)
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