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// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
#pragma once
#include "tasking_global.h"
#include "tasktree.h"
#include <QtConcurrent>
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)
{
return 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();
}
QFuture<ResultType> future() const { return m_future; }
private:
template <typename Function, typename ...Args>
void wrapConcurrent(Function &&function, Args &&...args)
{
m_startHandler = [=] {
if (m_threadPool)
return QtConcurrent::run(m_threadPool, function, args...);
return QtConcurrent::run(function, args...);
};
}
template <typename Function, typename ...Args>
void wrapConcurrent(std::reference_wrapper<const Function> &&wrapper, Args &&...args)
{
m_startHandler = [=] {
if (m_threadPool) {
return QtConcurrent::run(m_threadPool,
std::forward<const Function>(wrapper.get()), args...);
}
return QtConcurrent::run(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() {
if (!this->task()->m_startHandler) {
emit this->done(false); // TODO: Add runtime assert
return;
}
m_watcher.reset(new QFutureWatcher<ResultType>);
this->connect(m_watcher.get(), &QFutureWatcherBase::finished, this, [this] {
emit this->done(!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;
};
} // namespace Tasking
TASKING_DECLARE_TEMPLATE_TASK(ConcurrentCallTask, Tasking::ConcurrentCallTaskAdapter);
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