--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/corelib/concurrent/qtconcurrentthreadengine.h Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,285 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, 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.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QTCONCURRENT_THREADENGINE_H
+#define QTCONCURRENT_THREADENGINE_H
+
+#include <QtCore/qglobal.h>
+
+#ifndef QT_NO_CONCURRENT
+
+#include <QtCore/qthreadpool.h>
+#include <QtCore/qfuture.h>
+#include <QtCore/qdebug.h>
+#include <QtCore/qtconcurrentexception.h>
+#include <QtCore/qwaitcondition.h>
+#include <QtCore/qatomic.h>
+#include <QtCore/qsemaphore.h>
+
+QT_BEGIN_HEADER
+QT_BEGIN_NAMESPACE
+
+QT_MODULE(Core)
+
+#ifndef qdoc
+
+namespace QtConcurrent {
+
+// The ThreadEngineBarrier counts worker threads, and allows one
+// thread to wait for all others to finish. Tested for its use in
+// QtConcurrent, requires more testing for use as a general class.
+class ThreadEngineBarrier
+{
+private:
+ // The thread count is maintained as an integer in the count atomic
+ // variable. The count can be either positive or negative - a negative
+ // count signals that a thread is waiting on the barrier.
+
+ // BC note: inlined code from Qt < 4.6 will expect to find the QMutex
+ // and QAtomicInt here. ### Qt 5: remove.
+ QMutex mutex;
+ QAtomicInt count;
+
+ QSemaphore semaphore;
+public:
+ ThreadEngineBarrier();
+ void acquire();
+ int release();
+ void wait();
+ int currentCount();
+ bool releaseUnlessLast();
+};
+
+enum ThreadFunctionResult { ThrottleThread, ThreadFinished };
+
+// The ThreadEngine controls the threads used in the computation.
+// Can be run in three modes: single threaded, multi-threaded blocking
+// and multi-threaded asynchronous.
+// The code for the single threaded mode is
+class Q_CORE_EXPORT ThreadEngineBase: public QRunnable
+{
+public:
+ // Public API:
+ ThreadEngineBase();
+ virtual ~ThreadEngineBase();
+ void startSingleThreaded();
+ void startBlocking();
+ void startThread();
+ bool isCanceled();
+ void waitForResume();
+ bool isProgressReportingEnabled();
+ void setProgressValue(int progress);
+ void setProgressRange(int minimum, int maximum);
+ void acquireBarrierSemaphore();
+
+protected: // The user overrides these:
+ virtual void start() {}
+ virtual void finish() {}
+ virtual ThreadFunctionResult threadFunction() { return ThreadFinished; }
+ virtual bool shouldStartThread() { return futureInterface ? !futureInterface->isPaused() : true; }
+ virtual bool shouldThrottleThread() { return futureInterface ? futureInterface->isPaused() : false; }
+private:
+ bool startThreadInternal();
+ void startThreads();
+ void threadExit();
+ bool threadThrottleExit();
+ void run();
+ virtual void asynchronousFinish() = 0;
+#ifndef QT_NO_EXCEPTIONS
+ void handleException(const QtConcurrent::Exception &exception);
+#endif
+protected:
+ QFutureInterfaceBase *futureInterface;
+ QThreadPool *threadPool;
+ ThreadEngineBarrier barrier;
+ QtConcurrent::internal::ExceptionStore exceptionStore;
+};
+
+
+template <typename T>
+class ThreadEngine : public virtual ThreadEngineBase
+{
+public:
+ typedef T ResultType;
+
+ virtual T *result() { return 0; }
+
+ QFutureInterface<T> *futureInterfaceTyped()
+ {
+ return static_cast<QFutureInterface<T> *>(futureInterface);
+ }
+
+ // Runs the user algorithm using a single thread.
+ T *startSingleThreaded()
+ {
+ ThreadEngineBase::startSingleThreaded();
+ return result();
+ }
+
+ // Runs the user algorithm using multiple threads.
+ // This function blocks until the algorithm is finished,
+ // and then returns the result.
+ T *startBlocking()
+ {
+ ThreadEngineBase::startBlocking();
+ return result();
+ }
+
+ // Runs the user algorithm using multiple threads.
+ // Does not block, returns a future.
+ QFuture<T> startAsynchronously()
+ {
+ futureInterface = new QFutureInterface<T>();
+
+ // reportStart() must be called before starting threads, otherwise the
+ // user algorithm might finish while reportStart() is running, which
+ // is very bad.
+ futureInterface->reportStarted();
+ QFuture<T> future = QFuture<T>(futureInterfaceTyped());
+ start();
+
+ acquireBarrierSemaphore();
+ threadPool->start(this);
+ return future;
+ }
+
+ void asynchronousFinish()
+ {
+ finish();
+ futureInterfaceTyped()->reportFinished(result());
+ delete futureInterfaceTyped();
+ delete this;
+ }
+
+
+ void reportResult(const T *_result, int index = -1)
+ {
+ if (futureInterface)
+ futureInterfaceTyped()->reportResult(_result, index);
+ }
+
+ void reportResults(const QVector<T> &_result, int index = -1, int count = -1)
+ {
+ if (futureInterface)
+ futureInterfaceTyped()->reportResults(_result, index, count);
+ }
+};
+
+// The ThreadEngineStarter class ecapsulates the return type
+// from the thread engine.
+// Depending on how the it is used, it will run
+// the engine in either blocking mode or asynchronous mode.
+template <typename T>
+class ThreadEngineStarterBase
+{
+public:
+ ThreadEngineStarterBase(ThreadEngine<T> *_threadEngine)
+ : threadEngine(_threadEngine) { }
+
+ inline ThreadEngineStarterBase(const ThreadEngineStarterBase &other)
+ : threadEngine(other.threadEngine) { }
+
+ QFuture<T> startAsynchronously()
+ {
+ return threadEngine->startAsynchronously();
+ }
+
+ operator QFuture<T>()
+ {
+ return startAsynchronously();
+ }
+
+protected:
+ ThreadEngine<T> *threadEngine;
+};
+
+
+// We need to factor out the code that dereferences the T pointer,
+// with a specialization where T is void. (code that dereferences a void *
+// won't compile)
+template <typename T>
+class ThreadEngineStarter : public ThreadEngineStarterBase<T>
+{
+ typedef ThreadEngineStarterBase<T> Base;
+ typedef ThreadEngine<T> TypedThreadEngine;
+public:
+ ThreadEngineStarter(TypedThreadEngine *eng)
+ : Base(eng) { }
+
+ T startBlocking()
+ {
+ T t = *this->threadEngine->startBlocking();
+ delete this->threadEngine;
+ return t;
+ }
+};
+
+// Full template specialization where T is void.
+template <>
+class ThreadEngineStarter<void> : public ThreadEngineStarterBase<void>
+{
+public:
+ ThreadEngineStarter<void>(ThreadEngine<void> *_threadEngine)
+ :ThreadEngineStarterBase<void>(_threadEngine) {}
+
+ void startBlocking()
+ {
+ this->threadEngine->startBlocking();
+ delete this->threadEngine;
+ }
+};
+
+template <typename ThreadEngine>
+inline ThreadEngineStarter<typename ThreadEngine::ResultType> startThreadEngine(ThreadEngine *threadEngine)
+{
+ return ThreadEngineStarter<typename ThreadEngine::ResultType>(threadEngine);
+}
+
+} // namespace QtConcurrent
+
+#endif //qdoc
+
+QT_END_NAMESPACE
+QT_END_HEADER
+
+#endif // QT_NO_CONCURRENT
+
+#endif