Re: [Cppcms-users] About raw filter translation.

[redred77 <red...@gm...>]

I think you over trusted compiler's inline function.
They do their best, but they can't skip making temporary objects.


1. So, I benchmarked.
Printed 1000000 times for each and measured with
Windows QueryPerformanceCounter().
Of course compiled for Release build. (Full Optimization)

out() << "/testtext";
out() << cppcms::filters::raw("/testtext");

Result :
0.109707 sec
0.120335 sec

So filters::raw() is actually slower about 9%.



2. You'll be surprised when you see the disassembly.

out() << "/testtext";

00FDC828  mov         ecx,ebx
00FDC82A  call        edi
00FDC82C  mov         edx,1026F50h
00FDC831  mov         ecx,eax
00FDC833  call        std::operator<<<std::char_traits<char> > (0FD1A30h)



out() << cppcms::filters::raw("/testtext");

00FDC838  push        1026F50h
00FDC83D  lea         ecx,[esp+50h]
00FDC841  call        dword ptr ds:[10131D8h]
00FDC847  lea         eax,[esp+4Ch]
00FDC84B  mov         dword ptr [esp+0D0h],2
00FDC856  push        eax
00FDC857  lea         ecx,[esp+2Ch]
00FDC85B  call        dword ptr ds:[10131CCh]
00FDC861  mov         esi,eax
00FDC863  mov         ecx,ebx
00FDC865  mov         byte ptr [esp+0D0h],3
00FDC86D  call        edi
00FDC86F  push        eax
00FDC870  mov         ecx,esi
00FDC872  call        dword ptr ds:[10131D4h]
00FDC878  lea         ecx,[esp+28h]
00FDC87C  mov         byte ptr [esp+0D0h],2
00FDC884  call        dword ptr ds:[10131D0h]
00FDC88A  lea         ecx,[esp+4Ch]
00FDC88E  mov         dword ptr [esp+0D0h],0FFFFFFFFh
00FDC899  call        dword ptr ds:[10131E0h]


There's so many call instructions that are actually not necessary at all.
It's because wrapping with filters::raw is not just call and return but it
makes and destroy temporary streamable object each time.

Here are brief call order. You can also follow this codes one by one with
your debugger.

streamable::streamable(char const *ptr)
streamable::streamable(streamable const &other)
raw::raw(streamable const &obj) : obj_(obj) {}
inline std::ostream &operator<<(std::ostream &out,raw const &obj)
void raw::operator()(std::ostream &out) const
void streamable::operator()(std::ostream &out) const
void ch_to_stream(std::ostream &out,void const *p)



3. What I like and decided to move to CppCMS the most is that it takes
performance seriously.
Maybe I'm too concerned about performance, but this is what I learned from
the server running currently. It crashed down so many times when visitors
explode.


Thanks.



2015-07-05 5:06 GMT+09:00 Joerg Sonnenberger <jo...@br...>:

> On Sun, Jul 05, 2015 at 02:09:16AM +0900, redred77 wrote:
> > It seems like raw filter in view template does nothing but just wraps
> input
> > variable.
> > So below two lines are just same.
> >
> > out()<<cppcms::filters::raw(content.hello);
> > out()<<content.hello;
> >
> > First one looks more structured which seems like to follow rules like
> other
> > filters.
> > But isn't it better for cppcms_tmpl_cc.py to translate like the second
> one
> > in a performance aspect view?
>
> It's inlined.
>
> Joerg
>
>
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