[Development] Cut 7+ms of Qt5 startup time on Linux

[Robert Knight]

There is already a caching mechanism in place for the Compose file,
can we make use of that? -
http://kdemonkey.blogspot.co.uk/2008/04/magic-trick.html

On 31 October 2013 07:38, Knoll Lars <Lars.Knoll at digia.com> wrote:
> Before going to a binary format, I’d first like to check whether we can
> further speed up the parsing. I’ve done some work in that area in spring,
> but I know there was still quite some room to improve it.
>
> Cheers,
> Lars
>
> From: Jiergir Ogoerg <f35f22fan at gmail.com>
> Date: torsdag 31. oktober 2013 04:10
> To: "<development at qt-project.org>" <development at qt-project.org>
> Subject: [Development] Cut 7+ms of Qt5 startup time on Linux
>
> Hi,
>
> Since each qt (gui) app on Linux parses the text file
> /usr/share/X11/locale/en_US.UTF-8/Compose
> line by line which on my computer is 549Kib (almost 6000 lines)
> it takes on my 64bit OS with Intel Core i5 about 7ms to parse,
> so the idea is to cache the locale file in binary format in the
> home/.kde directory (the binary file is also smaller than the other one),
> this new way takes less than 1ms to load since
> there's pretty much nothing to parse.
> That's the core idea.
> The user's locale changes (very) rarely if at all, so pretty
> much all the time he'll load the cached (quick) version,
> but when the locale does change or gets updated -
> the cache is updated accordingly.
>
> If this approach isn't good stop reading here and please let me
> know.
>
> I attached the 2 files in zip format.
>
> The source code is rather dirty cause it doesn't strictly adhere
> to the Qt coding style - my goal was a working solution.
>
> Since I don't represent any company and the changes are simple
> would somebody please take the changes and shape them into a
> mergeable commit or must I take all the steps to become an
> official contributor and polish the code to a mergeable state myself?
>
> Only 2 files affected:
> /qtbase/src/plugins/platforminputcontexts/compose/generator/qtablegenerator.cpp
> and
> /qtbase/src/plugins/platforminputcontexts/compose/generator/qtablegenerator.h
>
>
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