include/QtConcurrent/qtconcurrentrunbase.h

0001 // Copyright (C) 2016 The Qt Company Ltd.
0002 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
0003
0004 #ifndef QTCONCURRENT_RUNBASE_H
0005 #define QTCONCURRENT_RUNBASE_H
0006
0007 #include <QtConcurrent/qtconcurrent_global.h>
0008
0009 #ifndef QT_NO_CONCURRENT
0010
0011 #include <QtCore/qfuture.h>
0012 #include <QtCore/qrunnable.h>
0013 #include <QtCore/qthreadpool.h>
0014
0015 #include <type_traits>
0016 #include <utility>
0017
0018 QT_BEGIN_NAMESPACE
0019
0020
0021 #ifndef Q_QDOC
0022
0023 namespace QtConcurrent {
0024
0025 template <typename T>
0026 struct SelectSpecialization
0027 {
0028     template <class Normal, class Void>
0029     struct Type { typedef Normal type; };
0030 };
0031
0032 template <>
0033 struct SelectSpecialization<void>
0034 {
0035     template <class Normal, class Void>
0036     struct Type { typedef Void type; };
0037 };
0038
0039 struct TaskStartParameters
0040 {
0041     QThreadPool *threadPool = QThreadPool::globalInstance();
0042     int priority = 0;
0043 };
0044
0045 template <typename T>
0046 class RunFunctionTaskBase : public QRunnable
0047 {
0048 public:
0049     QFuture<T> start()
0050     {
0051         return start(TaskStartParameters());
0052     }
0053
0054     QFuture<T> start(const TaskStartParameters &parameters)
0055     {
0056         promise.setThreadPool(parameters.threadPool);
0057         promise.setRunnable(this);
0058         promise.reportStarted();
0059         QFuture<T> theFuture = promise.future();
0060
0061         if (parameters.threadPool) {
0062             parameters.threadPool->start(this, parameters.priority);
0063         } else {
0064             promise.reportCanceled();
0065             promise.reportFinished();
0066             delete this;
0067         }
0068         return theFuture;
0069     }
0070
0071     // For backward compatibility
0072     QFuture<T> start(QThreadPool *pool) { return start({pool, 0});  }
0073
0074     void run() override
0075     {
0076         if (promise.isCanceled()) {
0077             promise.reportFinished();
0078             return;
0079         }
0080 #ifndef QT_NO_EXCEPTIONS
0081         try {
0082 #endif
0083             runFunctor();
0084 #ifndef QT_NO_EXCEPTIONS
0085         } catch (QException &e) {
0086             promise.reportException(e);
0087         } catch (...) {
0088             promise.reportException(QUnhandledException(std::current_exception()));
0089         }
0090 #endif
0091         promise.reportFinished();
0092     }
0093
0094 protected:
0095     virtual void runFunctor() = 0;
0096
0097     QFutureInterface<T> promise;
0098 };
0099
0100 } //namespace QtConcurrent
0101
0102 #endif //Q_QDOC
0103
0104 QT_END_NAMESPACE
0105
0106 #endif // QT_NO_CONCURRENT
0107
0108 #endif