Move QtConcurrent into its own module

Task-number: QTBUG-20892

Change-Id: I614500aafb6428915509983608bbb0ade4e4f016
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 299 insertions, 0 deletions

diff --git a/src/concurrent/qtconcurrentthreadengine.cpp b/src/concurrent/qtconcurrentthreadengine.cpp
new file mode 100644
index 0000000000..774122674f
--- /dev/null
+++ b/src/concurrent/qtconcurrentthreadengine.cpp
@@ -0,0 +1,299 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** This file may be used under the terms of the GNU Lesser General Public
+** License version 2.1 as published by the Free Software Foundation and
+** appearing in the file LICENSE.LGPL included in the packaging of this
+** file. Please review the following information to ensure the GNU Lesser
+** General Public License version 2.1 requirements will be met:
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU General
+** Public License version 3.0 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 3.0 requirements will be met:
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qtconcurrentthreadengine.h"
+
+#ifndef QT_NO_CONCURRENT
+
+QT_BEGIN_NAMESPACE
+
+namespace QtConcurrent {
+
+ThreadEngineBarrier::ThreadEngineBarrier()
+:count(0) { }
+
+void ThreadEngineBarrier::acquire()
+{
+    forever {
+        int localCount = count.load();
+        if (localCount < 0) {
+            if (count.testAndSetOrdered(localCount, localCount -1))
+                return;
+        } else {
+            if (count.testAndSetOrdered(localCount, localCount + 1))
+                return;
+        }
+    }
+}
+
+int ThreadEngineBarrier::release()
+{
+    forever {
+        int localCount = count.load();
+        if (localCount == -1) {
+            if (count.testAndSetOrdered(-1, 0)) {
+                semaphore.release();
+                return 0;
+            }
+        } else if (localCount < 0) {
+            if (count.testAndSetOrdered(localCount, localCount + 1))
+                return qAbs(localCount + 1);
+        } else {
+            if (count.testAndSetOrdered(localCount, localCount - 1))
+                return localCount - 1;
+        }
+    }
+}
+
+// Wait until all threads have been released
+void ThreadEngineBarrier::wait()
+{
+    forever {
+        int localCount = count.load();
+        if (localCount == 0)
+            return;
+
+        Q_ASSERT(localCount > 0); // multiple waiters are not allowed.
+        if (count.testAndSetOrdered(localCount, -localCount)) {
+            semaphore.acquire();
+            return;
+        }
+    }
+}
+
+int ThreadEngineBarrier::currentCount()
+{
+    return count.load();
+}
+
+// releases a thread, unless this is the last thread.
+// returns true if the thread was released.
+bool ThreadEngineBarrier::releaseUnlessLast()
+{
+    forever {
+        int localCount = count.load();
+        if (qAbs(localCount) == 1) {
+            return false;
+        } else if (localCount < 0) {
+            if (count.testAndSetOrdered(localCount, localCount + 1))
+                return true;
+        } else {
+            if (count.testAndSetOrdered(localCount, localCount - 1))
+                return true;
+        }
+    }
+}
+
+ThreadEngineBase::ThreadEngineBase()
+:futureInterface(0), threadPool(QThreadPool::globalInstance())
+{
+    setAutoDelete(false);
+}
+
+ThreadEngineBase::~ThreadEngineBase() {}
+
+void ThreadEngineBase::startSingleThreaded()
+{
+    start();
+    while (threadFunction() != ThreadFinished)
+        ;
+    finish();
+}
+
+void ThreadEngineBase::startBlocking()
+{
+    start();
+    barrier.acquire();
+    startThreads();
+
+    bool throttled = false;
+#ifndef QT_NO_EXCEPTIONS
+    try {
+#endif
+        while (threadFunction() == ThrottleThread) {
+            if (threadThrottleExit()) {
+                throttled = true;
+                break;
+            }
+        }
+#ifndef QT_NO_EXCEPTIONS
+    } catch (QtConcurrent::Exception &e) {
+        handleException(e);
+    } catch (...) {
+        handleException(QtConcurrent::UnhandledException());
+    }
+#endif
+
+    if (throttled == false) {
+        barrier.release();
+    }
+
+    barrier.wait();
+    finish();
+    exceptionStore.throwPossibleException();
+}
+
+void ThreadEngineBase::startThread()
+{
+    startThreadInternal();
+}
+
+void ThreadEngineBase::acquireBarrierSemaphore()
+{
+    barrier.acquire();
+}
+
+bool ThreadEngineBase::isCanceled()
+{
+    if (futureInterface)
+        return futureInterface->isCanceled();
+    else
+        return false;
+}
+
+void ThreadEngineBase::waitForResume()
+{
+    if (futureInterface)
+        futureInterface->waitForResume();
+}
+
+bool ThreadEngineBase::isProgressReportingEnabled()
+{
+    // If we don't have a QFuture, there is no-one to report the progress to.
+    return (futureInterface != 0);
+}
+
+void ThreadEngineBase::setProgressValue(int progress)
+{
+    if (futureInterface)
+        futureInterface->setProgressValue(progress);
+}
+
+void ThreadEngineBase::setProgressRange(int minimum, int maximum)
+{
+    if (futureInterface)
+        futureInterface->setProgressRange(minimum, maximum);
+}
+
+bool ThreadEngineBase::startThreadInternal()
+{
+    if (this->isCanceled())
+        return false;
+
+    barrier.acquire();
+    if (!threadPool->tryStart(this)) {
+        barrier.release();
+        return false;
+    }
+    return true;
+}
+
+void ThreadEngineBase::startThreads()
+{
+    while (shouldStartThread() && startThreadInternal())
+        ;
+}
+
+void ThreadEngineBase::threadExit()
+{
+    const bool asynchronous = futureInterface != 0;
+    const int lastThread = (barrier.release() == 0);
+
+    if (lastThread && asynchronous)
+        this->asynchronousFinish();
+}
+
+// Called by a worker thread that wants to be throttled. If the current number
+// of running threads is larger than one the thread is allowed to exit and
+// this function returns one.
+bool ThreadEngineBase::threadThrottleExit()
+{
+    return barrier.releaseUnlessLast();
+}
+
+void ThreadEngineBase::run() // implements QRunnable.
+{
+    if (this->isCanceled()) {
+        threadExit();
+        return;
+    }
+
+    startThreads();
+
+#ifndef QT_NO_EXCEPTIONS
+    try {
+#endif
+        while (threadFunction() == ThrottleThread) {
+            // threadFunction returning ThrottleThread means it that the user
+            // struct wants to be throttled by making a worker thread exit.
+            // Respect that request unless this is the only worker thread left
+            // running, in which case it has to keep going.
+            if (threadThrottleExit())
+                return;
+        }
+
+#ifndef QT_NO_EXCEPTIONS
+    } catch (QtConcurrent::Exception &e) {
+        handleException(e);
+    } catch (...) {
+        handleException(QtConcurrent::UnhandledException());
+    }
+#endif
+    threadExit();
+}
+
+#ifndef QT_NO_EXCEPTIONS
+
+void ThreadEngineBase::handleException(const QtConcurrent::Exception &exception)
+{
+    if (futureInterface)
+        futureInterface->reportException(exception);
+    else
+        exceptionStore.setException(exception);
+}
+#endif
+
+
+} // namepsace QtConcurrent
+
+QT_END_NAMESPACE
+
+#endif // QT_NO_CONCURRENT