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Re: Hopefully final C++11 related disruptive change: Callback now deprecated [message #46998 is a reply to message #46985]

Thu, 13 October 2016 08:57

mirek
Messages: 13978
Registered: November 2005

Ultimate Member

Mindtraveller wrote on Mon, 10 October 2016 14:33

Thank you. Is it possible to say at least for MSC15/CLANG3.4 how this "native" callback impacts effectivenes? Do we really achieve better timing replacing U++ callbacks?

Well, it definitely was not a primary concern (I am OK if new are 'about the same speed'), however it is an interesting question. So I have put it to the test:

MSC15x64 Release MT

Callback, U++ classic:

#include <Core/Core.h>

using namespace Upp;

struct Test {
	int sum;

	Vector<Callback> cb;
	
	void Method1() {
		sum++;
	}
	
	void Method2(int d) {
		sum += d;
	}
	
	typedef Test CLASSNAME;
	
	Test() {
		const int N = 1000000;
		for(int j = 0; j < 50; j++) {
			cb.Clear();
			for(int i = 0; i < N; i++) {
				RTIMING("Adding Method1");
				cb.Add(THISBACK(Method1));
			}
			sum = 0;
			for(int i = 0; i < cb.GetCount(); i++) {
				RTIMING("Calling Method1");
				cb[i]();
			}
			RDUMP(sum);
			cb.Clear();
			for(int i = 0; i < N; i++) {
				RTIMING("Adding Method2");
				cb.Add(THISBACK1(Method2, i));
			}
			sum = 0;
			for(int i = 0; i < cb.GetCount(); i++) {
				RTIMING("Calling Method2");
				cb[i]();
			}
			RDUMP(sum);
		}
	}
};

CONSOLE_APP_MAIN
{
	Test();
}

Lambdas and Event<>, 'new U++':

#include <Core/Core.h>

using namespace Upp;

struct Test {
	int sum;

	Vector<Event<>> cb;
	
	void Method1() {
		sum++;
	}
	
	void Method2(int d) {
		sum += d;
	}
	
	typedef Test CLASSNAME;
	
	Test() {
		const int N = 1000000;
		for(int j = 0; j < 50; j++) {
			cb.Clear();
			for(int i = 0; i < N; i++) {
				RTIMING("Adding Method1");
				cb.Add([=] { Method1(); });
			}
			sum = 0;
			for(int i = 0; i < cb.GetCount(); i++) {
				RTIMING("Calling Method1");
				cb[i]();
			}
			RDUMP(sum);
			cb.Clear();
			for(int i = 0; i < N; i++) {
				RTIMING("Adding Method2");
				cb.Add([=] { Method2(i); });
			}
			sum = 0;
			for(int i = 0; i < cb.GetCount(); i++) {
				RTIMING("Calling Method2");
				cb[i]();
			}
			RDUMP(sum);
		}
	}
};

CONSOLE_APP_MAIN
{
	Test();
}

classic Callbacks:

TIMING Calling Method2: 221.43 ms -  4.43 ns ( 1.61 s  / 50000000 ), min:  0.00 ns, max:  1.00 ms, nesting: 1 - 50000000
TIMING Adding Method2 :  1.78 s  - 35.55 ns ( 3.17 s  / 50000000 ), min:  0.00 ns, max:  4.00 ms, nesting: 1 - 50000000
TIMING Calling Method1: 157.43 ms -  3.15 ns ( 1.55 s  / 50000000 ), min:  0.00 ns, max:  1.00 ms, nesting: 1 - 50000000
TIMING Adding Method1 :  1.67 s  - 33.31 ns ( 3.06 s  / 50000000 ), min:  0.00 ns, max:  3.00 ms, nesting: 1 - 50000000

new Event<>s:

TIMING Calling Method2: 117.74 ms -  2.35 ns ( 1.45 s  / 50000000 ), min:  0.00 ns, max:  1.00 ms, nesting: 1 - 50000000
TIMING Adding Method2 :  1.09 s  - 21.87 ns ( 2.43 s  / 50000000 ), min:  0.00 ns, max:  3.00 ms, nesting: 1 - 50000000
TIMING Calling Method1: 85.74 ms -  1.71 ns ( 1.42 s  / 50000000 ), min:  0.00 ns, max:  1.00 ms, nesting: 1 - 50000000
TIMING Adding Method1 :  1.13 s  - 22.55 ns ( 2.46 s  / 50000000 ), min:  0.00 ns, max:  3.00 ms, nesting: 1 - 50000000

So interestingly, yes, it is a little bit faster. My guess there it is partly because of && (Adding part), partly because new C++11 implementation perhaps allows more inlining (Calling part).

Anyway, the main value for me is that about 4000 lines of code in classic Core were replaced by 100 lines in "C++11 Core" and 50+ of various types, macros and functions are now replaced by just 3 types and single macro. (Of course, we still these need to maintain these 50+ for BW compatibility and have now about 300 lines to achieve that. But the new system is overall much simpler).

[Updated on: Thu, 13 October 2016 08:57]

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