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List:       kde-optimize
Subject:    normalized signature of signals/slots
From:       Olivier Goffart <ogoffart () kde ! org>
Date:       2005-11-12 10:30:50
Message-ID: 200511121130.57257.ogoffart () kde ! org
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Hello

When browsing the Qt code, i saw that Qt first try to connect signals without 
normalize the signature, and if it fails, it normalize the slot signature and 
retry .

So using normalized signature in signal slot connection is faster that don't
But how much,  maybe that's negligible ?

After some test (attached) I noticed that the normalized signature is about 
twice times faster than the not normalized one 
(This may i guess be even more in the case of bigger signatures, or class with 
more signals and slots)

Usually, we don't use normalized signature: Less intuitive, and the one 
KDevelop auto-complete (nice feature btw) is not normalized.

Does it make sens to write a script that normalize signatures in the code ?


["test_signals.cpp" (text/x-c++src)]

#include "test_signals.h"

#include <QDateTime>

#include <iostream>

void Test::someSlot(const QString&,const QString&) {};

int main()
{
	int normalized_time;
	int cu_time;
	QTime ti;
	Test t;

	ti.start();
	for(int f=0;f<20000;f++)
	{
		QObject::connect(&t,SIGNAL(someSignal(QString,QString)) , &t, \
SLOT(someSlot(QString,QString)));  \
QObject::disconnect(&t,SIGNAL(someSignal(QString,QString)) , &t, \
SLOT(someSlot(QString,QString)));  \
QObject::connect(&t,SIGNAL(someSignal(QString,QString)) , &t, \
SLOT(someSlot(QString,QString)));  \
QObject::disconnect(&t,SIGNAL(someSignal(QString,QString)) , &t, \
SLOT(someSlot(QString,QString)));  \
QObject::connect(&t,SIGNAL(someSignal(QString,QString)) , &t, \
SLOT(someSlot(QString,QString)));  \
QObject::disconnect(&t,SIGNAL(someSignal(QString,QString)) , &t, \
SLOT(someSlot(QString,QString)));  }
	normalized_time=ti.elapsed();
	std::cout << "normalized: " << normalized_time <<  "ms\n";


	ti.start();
	for(int f=0;f<20000;f++)
	{
		QObject::connect(&t,SIGNAL(someSignal(const QString&, const QString&)) , &t, \
SLOT(someSlot(const QString&, const QString&)));  \
QObject::disconnect(&t,SIGNAL(someSignal(const QString&, const QString&)) , &t, \
SLOT(someSlot(const QString&, const QString&)));  \
QObject::connect(&t,SIGNAL(someSignal(const QString&, const QString&)) , &t, \
SLOT(someSlot(const QString&, const QString&)));  \
QObject::disconnect(&t,SIGNAL(someSignal(const QString&, const QString&)) , &t, \
SLOT(someSlot(const QString&, const QString&)));  \
QObject::connect(&t,SIGNAL(someSignal(const QString&, const QString&)) , &t, \
SLOT(someSlot(const QString&, const QString&)));  \
QObject::disconnect(&t,SIGNAL(someSignal(const QString&, const QString&)) , &t, \
SLOT(someSlot(const QString&, const QString&)));  }
	cu_time=ti.elapsed();
	std::cout << "usual: " << cu_time <<  "ms    ratio: "<< \
(double)cu_time/(double)normalized_time  <<"\n";  
	return 1;
}


#include "test_signals.moc"


["test_signals.h" (text/x-c++hdr)]

#ifndef TTTTT
#define TTTTT

#include <QObject>
#include <QString>

class Test : public QObject
{ Q_OBJECT
public slots:
	#ifndef SALUT
	void someSlot(const QString& str, const QString &str2);
signals:
	void someSignal(const QString& str, const QString &str2);
	#endif
};

#endif

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