Re: [pygccxml-development] Another performance tweak

[Allen B. <al...@vr...>]

Roman Yakovenko wrote:

> On 8/26/06, Allen Bierbaum <al...@vr...> wrote:
>
>> I just found some more tweaks.
>
>
> Cool. I just committed a set of changes that will allow us to keep 
> under control
> cache results of different algorithms. I still have to write unit 
> tests. These
> changes allow you to continue grate work. Please take a look on them, 
> what
> do you think?

Not quite how I would have done it, but it looks like it should work.  
It may eliminate an extra attribute lookup I had to do so that could 
increase the performance even more.

>> - Caching the results of type_traits.remove_alias improved performance
>> by 20%
>
>
> Yes, this algorithms is used every where. Please don't commit this
> change, I'd like
> to think about it. I see next problem here: there are a lot of types,
> so the cache
> memory size could go out of control. Can you find out how many memory
> Py++ takes with\without the cache?

I can try to take a look at this.  I don't have an easy way to do it 
right now but I will try later.

>
>> - (danger) Having create_identifier just return the exact same string
>> passed as full_name improved performance another 20%.
>>
>> This last one was interesting because what I found was that (at least in
>> my project) create_identifier was called about 16,000 times and it
>> always returned the same value passed in.  This could be just because of
>> how my project works (no namespace aliases that I know of) and is
>> probably not portable.
>>
>> But, one very strange thing is why is this method being called for names
>> like "boost::python::arg" and "boost::python::default_call_policies"?
>> As far as I understand how py++ is working, these symbols are always
>> going to be valid.  So why waste the time calling an expensive method if
>> we already know the outcome?
>
>
> :-) It seems that you missed the point. Py++ has few cool features.
>
> mb = module_builder_t( ... )
> mb.build_code_creator(...)
> mb.code_creator.add_namespace_alias( "bpl", "::boost::python" )
> or
> mb.code_creator.add_namespace_usage( "::boost::python" )
>
> See what happens.
>
> The short version is that you can add to the code creators tree the 
> namespace
> usage and aliase and Py++ will generate code that takes into account 
> them.
>
> create_identfier function is responsible for creating such identifier.
>
> It is safe to add such optimization, but similar work should be done.
>
If you never call add_namespace_usage or add_namespace_alias, then will 
create_identifier ever need to do anything?  Maybe we could make an 
optimization that keeps a global flag around and just skips the work in 
this method if you never set any namespace information.  What do you think?

-Allen