D11282: less expensive findByUrl in KCoreDirListerCache

[Stefan Brüns]

bruns added inline comments.

INLINE COMMENTS

> dfaure wrote in kcoredirlister.cpp:852
> That was the case already.... hmm but not in my version of kio. It looks like this patch is on top of other patches.

D10742 <https://phabricator.kde.org/D10742> - this makes it even harder to review ...

> mwolff wrote in kcoredirlister.cpp:1970
> O(N) iteration over a large hash is extremely slow, is this done elsewhere? if so, then you may need to find an alternative approach - potentially via multiple containers or by using a sorted vector after all like you proposed initially

My proposal:
A few lines earlier, a `KFileItemList` (~`QList<KFileItem`) is created.
Sort this list by name.

Use a ordered container (e.g. `QMap`) instead of `QHash`.

You can iterate the `QMap` and the `KFileItemList` in parallel, which makes erasing an O(m + n) iteration, instead of O(m * n). (Of course, on top you have sorting of the KFileItemList - O(n log n) - and the overhead when inserting into the QMap<QUrl, KFileItem>)

REPOSITORY
  R241 KIO

REVISION DETAIL
  https://phabricator.kde.org/D11282

To: jtamate, #frameworks, dfaure
Cc: kde-frameworks-devel, bruns, mwolff, michaelh, ngraham
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