Review Request 125220: KService: use a real global static for QThreadStorage rather than Q_GLOBAL_STATIC.

[Thiago Macieira]

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Aye, QThreadStorage isn't meant to be used in a Q_GLOBAL_STATIC. I don't understand what you meant by id: QThreadStorageData::get can only be called once the construction has finished, in which case there aren't multiple threads racing.

- Thiago Macieira


On Set. 13, 2015, 10:10 p.m., David Faure wrote:
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> (Updated Set. 13, 2015, 10:10 p.m.)
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> Review request for KDE Frameworks, Olivier Goffart and Thiago Macieira.
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> Repository: kservice
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> Description
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> Creating QThreadStorage on demand leads to race conditions because the
> id of the storagedata gets assigned once multiple threads are running,
> and read from other threads without locking. I almost submitted a fix for
> Qt when I realized the indirection I had here was unnecessary and wrong.
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> QThreadStorage must be created in the main thread, before any thread is running.
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> 
> Diffs
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>   src/services/kservicetypefactory.cpp 62fd230b4f7a6558c707d257796c5967f39c3607 
>   src/services/kservicegroupfactory.cpp 08e0bdcd765ab08afdb71cabc640fd21a73f4218 
>   src/services/kservicefactory.cpp 9b0e0c199818fea774c08a4f8fab5aca417927c8 
>   src/services/kmimetypefactory.cpp ba07aa0bc9b5d528454cf426b1feadb049402123 
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> Diff: https://git.reviewboard.kde.org/r/125220/diff/
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> Testing
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> helgrind ksycocathreadtest no longer complains about a race on QThreadStorageData::id
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> Thanks,
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> David Faure
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