Review Request 127866: Oxygen: Fix QCache usage

Hugo Pereira Da Costa hugo.pereira.da.costa at gmail.com
Mon May 30 12:34:18 BST 2016


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Hi, 
thanks for the updated patch. No more objection.
Just wanted to mention that in principle, tileset could probably be passed around by value too: they are "mostly" only a QVector<QPixmap> (which would be implicitely cached, right ?), and a bunch of integers. So that copying them should not involve too much operations.

- Hugo Pereira Da Costa


On May 22, 2016, 4:20 a.m., Michael Pyne wrote:
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> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/127866/
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> (Updated May 22, 2016, 4:20 a.m.)
> 
> 
> Review request for kde-workspace and Hugo Pereira Da Costa.
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> Repository: oxygen
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> Description
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> This should mostly complete the QCache fixes I kicked off in a previous RR, 127837. Hugo noted there were many other similar usages, and boy he wasn't kidding! ;) The long story short is that these usages can theoretically cause use-after-free behavior (which can lead to crashes and even undefined behavior if the compiler ever gets smart).
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> *NOTE* It is -much- easier to review if you download the diff to your git repository for oxygen and then run "git diff -b" to ignore whitespace changes, particularly for the QPixmap changes.
> 
> For QPixmaps we return values instead of pointers, so we simply make a separate copy to be cached when we do insert. For QColor we return references to values so we *must* return pointers, and those have to be owned by a QCache to avoid memleaks. So I added a helper function to loop until the cache accepts the new entry. TileSets are a similar concern, except those have manual loops since I was uncertain about whether TileSet's copy constructor was the best idea or not.
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> This fixes a ton of Coverity issues (59717 - 259733, 259739, 259742 - 259752, 1336154, 1336155) and might be associated with Qt bug 38142 and KDE bug 219055 (which doesn't actually appear to be a dupe of a different bug to me...).
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> 
> Diffs
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>   kdecoration/oxygendecohelper.cpp aa75eca 
>   kstyle/oxygenstyle.cpp e428606 
>   kstyle/oxygenstylehelper.h 9510a60 
>   kstyle/oxygenstylehelper.cpp 612ba37 
>   liboxygen/oxygenhelper.h a6453a0 
>   liboxygen/oxygenhelper.cpp 4843604 
>   liboxygen/oxygenshadowcache.cpp 907e586 
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> Diff: https://git.reviewboard.kde.org/r/127866/diff/
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> Testing
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> Compiled without warnings, installed and ran `oxygen-demo5 -style oxygen`. Used the GUI Benchmark feature to automatically cycle through all the listed features -- no crashes or obvious rendering errors.
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> 
> Thanks,
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> Michael Pyne
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>

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