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// Copyright (C) 2018 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
#include <QtTest>
#include <functional>
#include <vector>
/*
Config: Using QtTest library 5.10.0, Qt 5.10.0 (x86_64-little_endian-lp64 shared (dynamic)
debug build; by GCC 7.2.1 20171205)
PASS : BenchmarkSignals::qtMemfun()
0.000068 msecs per iteration (total: 72, iterations: 1048576)
PASS : BenchmarkSignals::qtLambda()
0.000066 msecs per iteration (total: 70, iterations: 1048576)
PASS : BenchmarkSignals::manualBind()
0.00011 msecs per iteration (total: 60, iterations: 524288)
PASS : BenchmarkSignals::manualLambda()
0.000043 msecs per iteration (total: 91, iterations: 2097152)
CONFIG += release
********* Start testing of BenchmarkSignals *********
PASS : BenchmarkSignals::qtMemfun()
0.000061 msecs per iteration (total: 64, iterations: 1048576)
PASS : BenchmarkSignals::qtLambda()
0.000058 msecs per iteration (total: 61, iterations: 1048576)
// Not completely surprising, as all the top call can be inlined
PASS : BenchmarkSignals::manualBind()
0.0000078 msecs per iteration (total: 66, iterations: 8388608)
PASS : BenchmarkSignals::manualLambda()
0.00000596 msecs per iteration (total: 100, iterations: 16777216)
PASS : BenchmarkSignals::cleanupTestCase()
The latter in instructions:
PASS : BenchmarkSignals::qtMemfun()
445 instruction reads per iteration (total: 445, iterations: 1)
PASS : BenchmarkSignals::qtLambda()
440 instruction reads per iteration (total: 440, iterations: 1)
PASS : BenchmarkSignals::manualBind()
113 instruction reads per iteration (total: 113, iterations: 1)
PASS : BenchmarkSignals::manualLambda()
107 instruction reads per iteration (total: 107, iterations: 1)
*/
template <typename Type>
class NaiveSignal
{
public:
using Callable = std::function<Type>;
void connect(const Callable &callable) { m_callables.push_back(callable); }
template <typename ...Args>
void operator()(Args ...args) const
{
for (const Callable &callable : m_callables)
callable(args...);
}
private:
std::vector<Callable> m_callables;
};
class BenchmarkSignals : public QObject
{
Q_OBJECT
public:
BenchmarkSignals() {}
private slots:
void qtMemfun();
void qtLambda();
void manualBind();
void manualLambda();
};
class Tester : public QObject
{
Q_OBJECT
public:
NaiveSignal<void(int)> naiveSignal;
signals:
void qtSignal(int);
public:
void doit(int i) { sum += i; }
int sum = 0;
};
void BenchmarkSignals::qtMemfun()
{
Tester tester;
connect(&tester, &Tester::qtSignal, &tester, &Tester::doit);
QBENCHMARK {
tester.qtSignal(1);
}
}
void BenchmarkSignals::qtLambda()
{
Tester tester;
connect(&tester, &Tester::qtSignal, [&](int x) { tester.sum += x; });
QBENCHMARK {
tester.qtSignal(1);
}
}
void BenchmarkSignals::manualBind()
{
Tester tester;
tester.naiveSignal.connect(std::bind(&Tester::doit, &tester, std::placeholders::_1));
QBENCHMARK {
tester.naiveSignal(1);
}
}
void BenchmarkSignals::manualLambda()
{
Tester tester;
tester.naiveSignal.connect([&](int x) { tester.sum += x; });
QBENCHMARK {
tester.naiveSignal(1);
}
}
QTEST_MAIN(BenchmarkSignals)
#include "tst_bench_signals.moc"
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