qtconcurrentrunbase.h

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#ifndef QTCONCURRENT_RUNBASE_H
#define QTCONCURRENT_RUNBASE_H
 
#include <QtConcurrent/qtconcurrent_global.h>
 
#ifndef QT_NO_CONCURRENT
 
#include <QtCore/qfuture.h>
#include <QtCore/qrunnable.h>
#include <QtCore/qthreadpool.h>
 
#include <type_traits>
#include <utility>
 
QT_BEGIN_NAMESPACE
 
 
#ifndef Q_QDOC
 
namespace QtConcurrent {
 
template <typename T>
struct SelectSpecialization
{
    template <class Normal, class Void>
    struct Type { typedef Normal type; };
};
 
template <>
struct SelectSpecialization<void>
{
    template <class Normal, class Void>
    struct Type { typedef Void type; };
};
 
struct TaskStartParameters
{
    QThreadPool *threadPool = QThreadPool::globalInstance();
    int priority = 0;
};
 
template <typename T>
class RunFunctionTaskBase : public QRunnable
{
public:
    QFuture<T> start()
    {
        return start(TaskStartParameters());
    }
 
    QFuture<T> start(const TaskStartParameters &parameters)
    {
        promise.setThreadPool(parameters.threadPool);
        promise.setRunnable(this);
        promise.reportStarted();
        QFuture<T> theFuture = promise.future();
 
        if (parameters.threadPool) {
            parameters.threadPool->start(this, parameters.priority);
        } else {
            promise.reportCanceled();
            promise.reportFinished();
            delete this;
        }
        return theFuture;
    }
 
    // For backward compatibility
    QFuture<T> start(QThreadPool *pool) { return start({pool, 0});  }
 
    void run() override
    {
        if (promise.isCanceled()) {
            promise.reportFinished();
            return;
        }
#ifndef QT_NO_EXCEPTIONS
        try {
#endif
            runFunctor();
#ifndef QT_NO_EXCEPTIONS
        } catch (QException &e) {
            promise.reportException(e);
        } catch (...) {
            promise.reportException(QUnhandledException(std::current_exception()));
        }
#endif
        promise.reportFinished();
    }
 
protected:
    virtual void runFunctor() = 0;
 
    QFutureInterface<T> promise;
};
 
} //namespace QtConcurrent
 
#endif //Q_QDOC
 
QT_END_NAMESPACE
 
#endif // QT_NO_CONCURRENT
 
#endif