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// Copyright (C) 2024 Jarek Kobus
// Copyright (C) 2024 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 TASKING_CONCURRENTCALL_H
#define TASKING_CONCURRENTCALL_H
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
#include "tasktree.h"
#include <QtConcurrent/QtConcurrent>
QT_BEGIN_NAMESPACE
namespace Tasking {
// This class introduces the dependency to Qt::Concurrent, otherwise Tasking namespace
// is independent on Qt::Concurrent.
// Possibly, it could be placed inside Qt::Concurrent library, as a wrapper around
// QtConcurrent::run() call.
template <typename ResultType>
class ConcurrentCall
{
Q_DISABLE_COPY_MOVE(ConcurrentCall)
public:
ConcurrentCall() = default;
template <typename Function, typename ...Args>
void setConcurrentCallData(Function &&function, Args &&...args)
{
wrapConcurrent(std::forward<Function>(function), std::forward<Args>(args)...);
}
void setThreadPool(QThreadPool *pool) { m_threadPool = pool; }
ResultType result() const
{
return m_future.resultCount() ? m_future.result() : ResultType();
}
QList<ResultType> results() const
{
return m_future.results();
}
QFuture<ResultType> future() const { return m_future; }
private:
template <typename Function, typename ...Args>
void wrapConcurrent(Function &&function, Args &&...args)
{
m_startHandler = [this, function = std::forward<Function>(function), args...] {
QThreadPool *threadPool = m_threadPool ? m_threadPool : QThreadPool::globalInstance();
return QtConcurrent::run(threadPool, function, args...);
};
}
template <typename Function, typename ...Args>
void wrapConcurrent(std::reference_wrapper<const Function> &&wrapper, Args &&...args)
{
m_startHandler = [this, wrapper = std::forward<std::reference_wrapper<const Function>>(wrapper), args...] {
QThreadPool *threadPool = m_threadPool ? m_threadPool : QThreadPool::globalInstance();
return QtConcurrent::run(threadPool, std::forward<const Function>(wrapper.get()),
args...);
};
}
template <typename T>
friend class ConcurrentCallTaskAdapter;
std::function<QFuture<ResultType>()> m_startHandler;
QThreadPool *m_threadPool = nullptr;
QFuture<ResultType> m_future;
};
template <typename ResultType>
class ConcurrentCallTaskAdapter : public TaskAdapter<ConcurrentCall<ResultType>>
{
public:
~ConcurrentCallTaskAdapter() {
if (m_watcher) {
m_watcher->cancel();
m_watcher->waitForFinished();
}
}
void start() final {
if (!this->task()->m_startHandler) {
emit this->done(DoneResult::Error); // TODO: Add runtime assert
return;
}
m_watcher.reset(new QFutureWatcher<ResultType>);
this->connect(m_watcher.get(), &QFutureWatcherBase::finished, this, [this] {
emit this->done(toDoneResult(!m_watcher->isCanceled()));
m_watcher.release()->deleteLater();
});
this->task()->m_future = this->task()->m_startHandler();
m_watcher->setFuture(this->task()->m_future);
}
private:
std::unique_ptr<QFutureWatcher<ResultType>> m_watcher;
};
template <typename T>
using ConcurrentCallTask = CustomTask<ConcurrentCallTaskAdapter<T>>;
} // namespace Tasking
QT_END_NAMESPACE
#endif // TASKING_CONCURRENTCALL_H
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