Make a benchmark out of tst_QObjectPerformance::emitToManyReceivers

The test has been flaky on top of QEMU. The test is clearly a sort of manually
rolled benchmark, not a regular autotest. Remove the test and replace it with a
benchmark in QObjectBenchmark.

Task-number: QTBUG-66823
Task-number: QTBUG-66216
Change-Id: I7a48293023f32141eed6fea50fbb63af18933a8f
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

tests/auto/other/other.pro

@@ -16,7 +16,6 @@ SUBDIRS=\
    qcomplextext \
    qfocusevent \
    qnetworkaccessmanager_and_qprogressdialog \
-   qobjectperformance \
    qobjectrace \
    qsharedpointer_and_qwidget \
    qprocess_and_guieventloop \
@@ -44,7 +43,6 @@ SUBDIRS=\
    lancelot \
    networkselftest \
    qnetworkaccessmanager_and_qprogressdialog \
-   qobjectperformance
 
 cross_compile: SUBDIRS -= \
    atwrapper \

tests/auto/other/qobjectperformance/.gitignore

@@ -1 +0,0 @@
-tst_qobjectperformance

tests/auto/other/qobjectperformance/qobjectperformance.pro

@@ -1,7 +0,0 @@
-CONFIG += testcase
-TARGET = tst_qobjectperformance
-SOURCES  += tst_qobjectperformance.cpp
-
-QT = core network testlib
-
-

tests/auto/other/qobjectperformance/tst_qobjectperformance.cpp

@@ -1,110 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2016 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the test suite of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:GPL-EXCEPT$
-** 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 https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 3 as published by the Free Software
-** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
-** included in the packaging of this file. Please review the following
-** information to ensure the GNU General Public License requirements will
-** be met: https://www.gnu.org/licenses/gpl-3.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-
-#include <QtTest/QtTest>
-
-#include <qcoreapplication.h>
-
-#include <qobject.h>
-
-class tst_QObjectPerformance : public QObject
-{
-    Q_OBJECT
-
-public:
-
-private slots:
-    void emitToManyReceivers();
-};
-
-class SimpleSenderObject : public QObject
-{
-    Q_OBJECT
-
-signals:
-    void signal();
-
-public:
-    void emitSignal()
-    {
-        emit signal();
-    }
-};
-
-class SimpleReceiverObject : public QObject
-{
-    Q_OBJECT
-
-public slots:
-    void slot()
-    {
-    }
-};
-
-void tst_QObjectPerformance::emitToManyReceivers()
-{
-    // ensure that emission times remain mostly linear as the number of receivers increase
-
-    SimpleSenderObject sender;
-    int elapsed = 0;
-    const int increase = 3000;
-    const int base = 5000;
-
-    for (int i = 0; i < 4; ++i) {
-        const int size = base + i * increase;
-        const double increaseRatio = double(size) / (double)(size - increase);
-
-        QList<SimpleReceiverObject *> receivers;
-        for (int k = 0; k < size; ++k) {
-            SimpleReceiverObject *receiver = new SimpleReceiverObject;
-            QObject::connect(&sender, SIGNAL(signal()), receiver, SLOT(slot()));
-            receivers.append(receiver);
-        }
-
-        QTime timer;
-        timer.start();
-        sender.emitSignal();
-        int e = timer.elapsed();
-
-        if (elapsed > 1) {
-            qDebug() << size << "receivers, elapsed time" << e << "compared to previous time" << elapsed;
-            QVERIFY(double(e) / double(elapsed) <= increaseRatio * 2.0);
-        } else {
-            qDebug() << size << "receivers, elapsed time" << e << "cannot be compared to previous, unmeasurable time";
-        }
-        elapsed = e;
-
-        qDeleteAll(receivers);
-        receivers.clear();
-    }
-}
-
-
-QTEST_MAIN(tst_QObjectPerformance)
-#include "tst_qobjectperformance.moc"

tests/benchmarks/corelib/kernel/qobject/main.cpp

@@ -43,6 +43,8 @@ Q_OBJECT
 private slots:
     void signal_slot_benchmark();
     void signal_slot_benchmark_data();
+    void signal_many_receivers();
+    void signal_many_receivers_data();
     void qproperty_benchmark_data();
     void qproperty_benchmark();
     void dynamic_property_benchmark();
@@ -127,6 +129,28 @@ void QObjectBenchmark::signal_slot_benchmark()
     }
 }
 
+void QObjectBenchmark::signal_many_receivers_data()
+{
+    QTest::addColumn<int>("receiverCount");
+    QTest::newRow("100 receivers") << 100;
+    QTest::newRow("1 000 receivers") << 1000;
+    QTest::newRow("10 000 receivers") << 10000;
+}
+
+void QObjectBenchmark::signal_many_receivers()
+{
+    QFETCH(int, receiverCount);
+    Object sender;
+    std::vector<Object> receivers(receiverCount);
+
+    for (Object &receiver : receivers)
+        QObject::connect(&sender, &Object::signal0, &receiver, &Object::slot0);
+
+    QBENCHMARK {
+        sender.emitSignal0();
+    }
+}
+
 void QObjectBenchmark::qproperty_benchmark_data()
 {
     QTest::addColumn<QByteArray>("name");