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Introduce swap functions for QPromise/QFutureInterface

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Made QPromise::swap public, added free standing swap() for
QFutureInterface and QPromise. Updated QPromise special member
functions. Extended tests

Task-number: QTBUG-84977
Change-Id: I5daf6876df306d082441dbcdf5ae4dee3bfc0ead
Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io>
This commit is contained in:
Andrei Golubev 2020-07-24 12:30:00 +02:00
parent fddb0c895f
commit b3c1093751
6 changed files with 59 additions and 21 deletions
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7
src/corelib/thread/qfutureinterface.cpp
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@ -1,6 +1,6 @@
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Copyright (C) 2020 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
@ -545,6 +545,11 @@ QFutureInterfaceBase &QFutureInterfaceBase::operator=(const QFutureInterfaceBase
return *this;
}
void QFutureInterfaceBase::swap(QFutureInterfaceBase &other) noexcept
{
qSwap(d, other.d);
}
bool QFutureInterfaceBase::refT() const
{
return d->refCount.refT();

10
src/corelib/thread/qfutureinterface.h
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@ -1,6 +1,6 @@
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Copyright (C) 2020 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
@ -163,6 +163,8 @@ public:
inline bool operator!=(const QFutureInterfaceBase &other) const { return d != other.d; }
QFutureInterfaceBase &operator=(const QFutureInterfaceBase &other);
void swap(QFutureInterfaceBase &other) noexcept;
protected:
bool refT() const;
bool derefT() const;
@ -426,6 +428,12 @@ public:
}
};
template<typename T>
inline void swap(QFutureInterface<T> &a, QFutureInterface<T> &b) noexcept
{
a.swap(b);
}
QT_END_NAMESPACE
#endif // QFUTUREINTERFACE_H

28
src/corelib/thread/qpromise.h
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@ -43,6 +43,8 @@
#include <QtCore/qglobal.h>
#include <QtCore/qfuture.h>
#include <utility>
QT_REQUIRE_CONFIG(future);
QT_BEGIN_NAMESPACE
@ -59,13 +61,12 @@ public:
Q_DISABLE_COPY(QPromise)
QPromise(QPromise<T> &&other) : d(other.d)
{
// In constructor, there's no need to perform swap(). Assign new
// QFutureInterface to other.d instead which is slightly cheaper.
other.d = QFutureInterface<T>();
}
QPromise& operator=(QPromise<T> &&other)
{
swap(other);
QPromise<T> tmp(std::move(other));
tmp.swap(*this);
return *this;
}
~QPromise()
@ -110,24 +111,25 @@ public:
d.setProgressValueAndText(progressValue, progressText);
}
void swap(QPromise<T> &other) noexcept
{
qSwap(this->d, other.d);
}
#if defined(Q_CLANG_QDOC) // documentation-only simplified signatures
void addResult(const T &result, int index = -1) { }
void addResult(T &&result, int index = -1) { }
#endif
private:
mutable QFutureInterface<T> d = QFutureInterface<T>();
void swap(QPromise<T> &other)
{
// Note: copy operations are expensive! They trigger several atomic
// reference counts
auto tmp = this->d;
this->d = other.d;
other.d = tmp;
}
};
template<typename T>
inline void swap(QPromise<T> &a, QPromise<T> &b) noexcept
{
a.swap(b);
}
QT_END_NAMESPACE
#endif // QPROMISE_H

5
src/corelib/thread/qpromise.qdoc
View File

@ -229,3 +229,8 @@
\sa QFuture::progressValue(), QFuture::progressText(), QFuture::cancel(),
reportFinished()
*/
/*! \fn template<typename T> void QPromise<T>::swap(QPromise<T> &other) noexcept
Swaps promise \a other with this promise. This operation is very fast and never fails.
*/

12
tests/auto/corelib/thread/qfuture/tst_qfuture.cpp
View File

@ -1,6 +1,6 @@
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Copyright (C) 2020 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the test suite of the Qt Toolkit.
@ -689,6 +689,16 @@ void tst_QFuture::futureInterface()
VoidResult a;
a.run().waitForFinished();
}
{
QFutureInterface<int> i1;
i1.reportResult(1);
QFutureInterface<int> i2;
i2.reportResult(2);
swap(i1, i2); // ADL must resolve this
QCOMPARE(i1.resultReference(0), 2);
QCOMPARE(i2.resultReference(0), 1);
}
}
template <typename T>

18
tests/auto/corelib/thread/qpromise/tst_qpromise.cpp
View File

@ -64,7 +64,7 @@ private slots:
void cancelWhenDestroyed();
#endif
void cancelWhenReassigned();
void finishWhenMoved();
void finishWhenSwapped();
void cancelWhenMoved();
void waitUntilResumed();
void waitUntilCanceled();
@ -470,7 +470,7 @@ void tst_QPromise::cancelWhenReassigned()
QCOMPARE(f.isCanceled(), true);
}
void tst_QPromise::finishWhenMoved()
void tst_QPromise::finishWhenSwapped()
{
QPromise<int> promise1;
auto f1 = promise1.future();
@ -482,8 +482,11 @@ void tst_QPromise::finishWhenMoved()
ThreadWrapper thr([&promise1, &promise2] () mutable {
QThread::msleep(100);
// There is swap semantics in move, so promise #1 and #2 just swap
promise1 = std::move(promise2);
promise1.addResult(0);
promise2.addResult(1);
swap(promise1, promise2); // ADL must resolve this
promise1.addResult(2);
promise2.addResult(3);
promise1.reportFinished(); // this finish is for future #2
promise2.reportFinished(); // this finish is for future #1
});
@ -497,6 +500,12 @@ void tst_QPromise::finishWhenMoved()
QCOMPARE(f2.isFinished(), true);
QCOMPARE(f2.isCanceled(), false);
QCOMPARE(f1.resultAt(0), 0);
QCOMPARE(f1.resultAt(1), 3);
QCOMPARE(f2.resultAt(0), 1);
QCOMPARE(f2.resultAt(1), 2);
}
void tst_QPromise::cancelWhenMoved()
@ -512,7 +521,6 @@ void tst_QPromise::cancelWhenMoved()
// Move promises to local scope to test cancellation behavior
ThreadWrapper thr([p1 = std::move(promise1), p2 = std::move(promise2)] () mutable {
QThread::msleep(100);
// There is swap semantics in move, so promise #1 and #2 just swap
p1 = std::move(p2);
p1.reportFinished(); // this finish is for future #2
});