[Development] RFC: Proposal for a semi-radical change in Qt APIs taking strings

[Thiago Macieira]

On Saturday 17 October 2015 19:42:27 Bubke Marco wrote:
> > Last time I profiled Qt Creator startup and parsing of projects, the two
> > most  expensive calls in QtCore were qHash and the SHA1 calculator. The
> > former I've already fixed. The latter I was hoping that some colleagues
> > would fix by creating an optimised library[1] we'd use but they refused
> > to add SHA1 support to it.
> 
> Thiago, we will be using clang as the new code model and in my experiences
> it is quite slow so we have to hide the latency. This is not only clang but
> same parsing of the results too where we heavily use a QByteArray wrapper.
> If I have time I will try out QValArray but it is not so urgent. I think
> QtCreator is an example that string operations matter because every latency
> as you type is quite unpleasant. 

Roberto's parser didn't use QByteArray either and performance with Creator was 
acceptable. If you replace that with the Clang parser and that's slower, we 
conclude that the fault lies with Clang.

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center