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Add benchmark for pathological O(N^2) behavior in QQmlChangeSet. 

This patch is just here for documentation of this behavior and does not
come with a fix yet. This hotspot was found while profiling the example
code attached to QTBUG-34391. It is triggered by the repeated calls
to _q_itemsMoved in QQmlDelegateModel::_q_layoutChanged.

Change-Id: I758744b3650c3c47dc86b914b823c3e9f96ce81e
Reviewed-by: Albert Astals Cid <albert.astals@canonical.com>
Reviewed-by: Daniel Vrátil <daniel.vratil@kdab.com>
Reviewed-by: Christopher Adams <chris.adams@jollamobile.com>
This commit is contained in:
Milian Wolff 2016-03-31 19:43:27 +02:00
parent b08a4c2f42
commit 9d4b556407
3 changed files with 71 additions and 0 deletions
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1
tests/benchmarks/qml/qml.pro
View File

@ -5,6 +5,7 @@ SUBDIRS += \
compilation \
javascript \
holistic \
qqmlchangeset \
qqmlcomponent \
qqmlimage \
qqmlmetaproperty \

10
tests/benchmarks/qml/qqmlchangeset/qqmlchangeset.pro Normal file
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@ -0,0 +1,10 @@
CONFIG += benchmark
TEMPLATE = app
TARGET = tst_qqmlchangeset
QT += qml quick-private testlib
osx:CONFIG -= app_bundle
SOURCES += tst_qqmlchangeset.cpp
DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0

60
tests/benchmarks/qml/qqmlchangeset/tst_qqmlchangeset.cpp Normal file
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@ -0,0 +1,60 @@
/****************************************************************************
**
** Copyright (C) 2016 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Milian Wolff <milian.wolff@kdab.com>
** Contact: http://www.qt.io/licensing/
**
** This file is part of the test suite of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** As a special exception, The Qt Company gives you certain additional
** rights. These rights are described in The Qt Company LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include <qtest.h>
#include <QDebug>
#include <private/qqmlchangeset_p.h>
class tst_qqmlchangeset : public QObject
{
Q_OBJECT
private slots:
void move();
};
void tst_qqmlchangeset::move()
{
QBENCHMARK {
QQmlChangeSet set;
const int MAX_ROWS = 30000;
for (int i = 0; i < MAX_ROWS; ++i) {
set.move(i, MAX_ROWS - 1 - i, 1, i);
}
}
}
QTEST_MAIN(tst_qqmlchangeset)
#include "tst_qqmlchangeset.moc"