ThreadPooler to replace ThreadWeaver

Initial version of ThreadPooler to substitute 3rd party ThreadWeaver.
Qt3D will be released under LGPLv3 and commercial licensing terms,
therefore we can't share code with free licenses.

Change-Id: Ic0956b40e4960002205ee32c19a053813339791c
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

1 files changed, 260 insertions, 0 deletions

diff --git a/src/core/jobs/qthreadpooler.cpp b/src/core/jobs/qthreadpooler.cpp
new file mode 100644
index 000000000..1620185b5
--- /dev/null
+++ b/src/core/jobs/qthreadpooler.cpp
@@ -0,0 +1,260 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the Qt3D module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL3$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPLv3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or later as published by the Free
+** Software Foundation and appearing in the file LICENSE.GPL included in
+** the packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 2.0 requirements will be
+** met: http://www.gnu.org/licenses/gpl-2.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qthreadpooler_p.h"
+#include "qthreadpooler_p_p.h"
+#include "jobrunner_p.h"
+#include "dependencyhandler_p.h"
+#include <QDebug>
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3D {
+
+QThreadPoolerPrivate::QThreadPoolerPrivate(QThreadPooler *qq)
+    : QObjectPrivate(),
+      m_mutex(new QMutex(QMutex::NonRecursive)),
+      m_runningThreads(0)
+{
+    q_ptr = qq;
+}
+
+QThreadPoolerPrivate::~QThreadPoolerPrivate()
+{
+    Q_FOREACH (QSharedPointer<TaskInterface> task, m_taskQueue)
+        task->setDependencyHandler(Q_NULLPTR);
+    delete m_dependencyHandler;
+
+    delete m_mutex;
+}
+
+void QThreadPoolerPrivate::shutdown()
+{
+    m_jobFinished.wakeAll();
+
+    // When shutting down a signal is send for jobrunners to exit run() loop
+    // on next round. Sometimes the jobrunner is busy doing still the clean up
+    // tasks and isn't waiting the release of WaitCondition. Repeat the waking
+    // process max tryOuts.
+    const int tryOuts = 2;
+
+    Q_FOREACH (JobRunner *jr, m_workers) {
+        if (!jr->isFinished()) {
+            for (int i = 0; i < tryOuts; i++) {
+                m_jobAvailable.wakeAll();
+                if (jr->wait(100))
+                    break;
+            }
+        }
+    }
+}
+
+
+bool QThreadPoolerPrivate::isQueueEmpty()
+{
+    return m_taskQueue.isEmpty();
+}
+
+void QThreadPoolerPrivate::incRunningThreads()
+{
+    m_runningThreads += 1;
+}
+
+void QThreadPoolerPrivate::decRunningThreads()
+{
+    m_runningThreads -= 1;
+
+    // Sanity check
+    if (m_runningThreads < 0)
+        m_runningThreads = 0;
+}
+
+void QThreadPoolerPrivate::createRunners(int threadCount)
+{
+    Q_Q(QThreadPooler);
+
+    for (int i = 0; i < threadCount; i++) {
+        JobRunner *jr = new JobRunner(q);
+
+        jr->setMutex(m_mutex);
+        jr->setWaitConditions(&(m_jobAvailable));
+        jr->start();
+
+        m_workers.append(jr);
+    }
+}
+
+int QThreadPoolerPrivate::maxThreadCount() const
+{
+    return m_maxThreadCount;
+}
+
+void QThreadPoolerPrivate::setMaxThreadCount(int threadCount)
+{
+
+    m_maxThreadCount = threadCount;
+    createRunners(m_maxThreadCount);
+}
+
+/////////////////////////////////////////////////
+
+QThreadPooler::QThreadPooler(QObject *parent)
+    : QObject(*new QThreadPoolerPrivate(this), parent)
+{
+}
+
+QThreadPooler::~QThreadPooler()
+{
+    Q_D(QThreadPooler);
+
+    emit shuttingDown();
+    d->m_jobAvailable.wakeAll();
+
+    d->shutdown();
+}
+
+int QThreadPooler::maxThreadCount() const
+{
+    Q_D(const QThreadPooler);
+
+    const QMutexLocker locker(d->m_mutex);
+
+    return d->maxThreadCount();
+}
+
+void QThreadPooler::setMaxThreadCount(int threadCount)
+{
+    Q_D(QThreadPooler);
+
+    const QMutexLocker locker(d->m_mutex);
+
+    d->setMaxThreadCount(threadCount);
+}
+
+QSharedPointer<TaskInterface> QThreadPooler::nextTask()
+{
+    Q_D(QThreadPooler);
+
+    const QMutexLocker locker(d->m_mutex);
+
+    QSharedPointer<TaskInterface> task;
+    int queueSize = d->m_taskQueue.size();
+    for (int i = 0; i < queueSize; i++) {
+        const QSharedPointer<TaskInterface> &candidate = d->m_taskQueue.at(i);
+        if (!hasDependencies(candidate)) {
+            task = candidate;
+            d->m_taskQueue.removeAt(i);
+
+            break;
+        }
+    }
+
+    return task;
+}
+
+bool QThreadPooler::hasDependencies(const QSharedPointer<TaskInterface> &task)
+{
+    DependencyHandler *handler = task->dependencyHandler();
+    if (handler)
+        return handler->hasDependency(task);
+
+    return false;
+}
+
+void QThreadPooler::enqueueTask(const QSharedPointer<TaskInterface> &task)
+{
+    Q_D(QThreadPooler);
+
+    const QMutexLocker locker(d->m_mutex);
+
+    d->m_taskQueue.append(task);
+    d->m_jobAvailable.wakeAll();
+}
+
+void QThreadPooler::flush()
+{
+    Q_D(QThreadPooler);
+
+    const QMutexLocker locker(d->m_mutex);
+
+#ifdef QT_NO_DEBUG
+    const int waitTime = 50;
+#else
+    const int waitTime = 500;
+#endif
+
+    while (!isIdling()) {
+        if (d->m_jobFinished.wait(d->m_mutex, waitTime) == false)
+            d->m_jobAvailable.wakeAll();
+    }
+}
+
+bool QThreadPooler::isIdling()
+{
+    Q_D(QThreadPooler);
+
+    return d->isQueueEmpty() && d->m_runningThreads == 0;
+}
+
+void QThreadPooler::startRunning()
+{
+    Q_D(QThreadPooler);
+
+    const QMutexLocker locker(d->m_mutex);
+
+    d->incRunningThreads();
+}
+
+void QThreadPooler::stopRunning()
+{
+    Q_D(QThreadPooler);
+
+    const QMutexLocker locker(d->m_mutex);
+
+    d->decRunningThreads();
+    d->m_jobFinished.wakeAll();
+}
+
+void QThreadPooler::setDependencyHandler(DependencyHandler *handler)
+{
+    Q_D(QThreadPooler);
+
+    d->setDependencyHandler(handler);
+}
+
+} // namespace Qt3D
+
+QT_END_NAMESPACE