Review Request 128944: Reduce temporary allocations in the DesktopFileParser

[Alex Richardson]

> On Sept. 19, 2016, 9:08 p.m., Alex Richardson wrote:
> > src/lib/plugin/desktopfileparser.cpp, line 478
> > <https://git.reviewboard.kde.org/r/128944/diff/1/?file=477140#file477140line478>
> >
> >     If I read this correctly we no longer handle leading/trailing spaces properly. Does the test still pass? Or maybe I forgot to add tests for this case.
> >     trimmed() will add another allocation, maybe we can change the string in place?
> >     
> >     There is `QStringRef::trimmed()` so `line.midRef(0).trimmed()` should work without any extra allocations, right?

`leftRef(-1)` is slightly more efficient so rather use that I guess


- Alex


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On Sept. 19, 2016, 4:20 p.m., Aleix Pol Gonzalez wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/128944/
> -----------------------------------------------------------
> 
> (Updated Sept. 19, 2016, 4:20 p.m.)
> 
> 
> Review request for KDE Frameworks.
> 
> 
> Repository: kcoreaddons
> 
> 
> Description
> -------
> 
> While analising plasmashell under heaptrack, one of the sore spots is temporary allocations within DesktopFileParser. This improves the situation by:
> 
> * Only converting to QString/utf8 once.
> * Using QStringRef instead of fully splitting QString to parse them.
> 
> 
> Diffs
> -----
> 
>   src/lib/plugin/desktopfileparser.cpp 2eb198d 
>   src/lib/plugin/desktopfileparser_p.h c61b297 
> 
> Diff: https://git.reviewboard.kde.org/r/128944/diff/
> 
> 
> Testing
> -------
> 
> tests still pass, plasma still works normally.
> 
> heaptrack plasmashell:
> 
> after:
>         allocations:            4169312
>         leaked allocations:     83225
>         temporary allocations:  606902
> 
> before:
>         allocations:            4680691
>         leaked allocations:     84825
>         temporary allocations:  819292
> 
> 
> Thanks,
> 
> Aleix Pol Gonzalez
> 
>

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