Re: qt: monolithic or modular?

[ludo@gnu.org (Ludovic Courtès)]

Efraim Flashner <efraim@flashner.co.il> skribis:

> On Thu, May 19, 2016 at 02:15:07PM +0200, Ludovic Courtès wrote:
>> Efraim Flashner <efraim@flashner.co.il> skribis:
>> 
>> > On Tue, Apr 05, 2016 at 07:22:20AM +0300, Efraim Flashner wrote:
>> >> I try very hard to not build qt on my laptop, mostly because of the long build time (7 hours on hydra [0]). Currently we download and use the big download of qt[1] and frankly I'd rather not. Qt does also ship in smaller bits[2], 32 if I counted correctly. I propose we package the submodules and over time we go through the packages that use qt and switch out the monolithic qt for just the parts that the program actually uses. It makes it less daunting to build, should make the closures smaller, and means that if a submodule fails to build on an architecture then they only lose that module, not all of qt.
>> >> 
>> >> [0] http://hydra.gnu.org/build/1114596
>> >> [1] https://download.qt.io/official_releases/qt/5.6/5.6.0/single/qt-everywhere-opensource-src-5.6.0.tar.xz
>> >> [2] https://download.qt.io/official_releases/qt/5.6/5.6.0/submodules/
>> >> 
>> >
>> > Finally got around to building qtbase out, took me 6 hours total on my
>> > machine. So since hydra[1] says it takes 7:15 it's a bit shorter. I
>> > haven't had a chance yet to try out qmake on the other modules or to try
>> > to optimize the build yet. One of the things I did want to try was
>> > replacing python2 with python-wrapper and enabling parallel-builds.
>> >
>> > I opted for straight out copying qt-5's build rather than inheriting so
>> > it'll be easier to remove it if/when we're ready, and I updated the
>> > license based on the text shown during build-time.
>> >
>> > I've attached what I have so far if anyone else wants to take a look at
>> > it while I'm working on it.
>> 
>> Nice!  I gather that some applications require more than just qtbase, so
>> we’d need to have all the different Qt components before we can fully
>> switch to this model, right?
>> 
>> Now, this could be done incrementally: we could start moving packages
>> that need nothing beyond qtbase to this new package, and so on.
>> 
>> Thoughts?
>
> That was my plan. Looking at nix's qt-5 it doesn't look like they even
> build all of the packages so hopefully it shouldn't be too long. My
> original hope that the base would take significantly less time didn't
> pan out, but this is still good. I'm now hoping that since qtbase took
> forever the other modules should be quick.

Cool.

>> 
>> > Also very worthy of note, qt-5.5.1 is listed at 288 MB, and qtbase-5.6.0
>> > is all of 85 MB.
>> >
>> > efraim@debian-netbook:~$ du -sch
>> > /gnu/store/r9bpiyz2w5bkavnx3s1ffxpgc51wa9z5-qtbase-5.6.0/*
>> > 6.6M    /gnu/store/r9bpiyz2w5bkavnx3s1ffxpgc51wa9z5-qtbase-5.6.0/bin
>> > 560K    /gnu/store/r9bpiyz2w5bkavnx3s1ffxpgc51wa9z5-qtbase-5.6.0/doc
>> > 25M     /gnu/store/r9bpiyz2w5bkavnx3s1ffxpgc51wa9z5-qtbase-5.6.0/examples
>> > 20M     /gnu/store/r9bpiyz2w5bkavnx3s1ffxpgc51wa9z5-qtbase-5.6.0/include
>> > 30M     /gnu/store/r9bpiyz2w5bkavnx3s1ffxpgc51wa9z5-qtbase-5.6.0/lib
>> > 2.5M    /gnu/store/r9bpiyz2w5bkavnx3s1ffxpgc51wa9z5-qtbase-5.6.0/mkspecs
>> > 2.6M    /gnu/store/r9bpiyz2w5bkavnx3s1ffxpgc51wa9z5-qtbase-5.6.0/plugins
>> > 85M total
>> 
>> It would be awesome if this would use the various configure flags that
>> our qt4 package is using, such that we don’t have weird top-level
>> directories such as ’mkspecs’ and ‘plugins’.
>> 
>> If would be worth trying to move doc/ and examples/ to a “doc” output,
>> but as noted in a comment in qt4, moving the examples may not be
>> possible.
>> 
>> Could you give it a try?
>> 
>
> mkspecs we actually might need, it has qmake.conf files for tons of
> different architecture/OS options.

Sure; I’m not suggesting to remove ‘mkspecs’, just to move it in a more
standard place, as done in qt4:

            "-importdir" (string-append out "/lib/qt-4"
                                        "/imports")

> Examples hopefully we can split out, but reading the note for qt-4 I'm
> not too optimistic. Docs don't look to me like they're big enough to
> bother with. Plugins has interface .so files for things like different
> sql databases and other stuff.

Ludo’.