Review Request 108824: New sorting algorithm for Dolphin

[Frank Reininghaus]

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> Thank you Frank, I will have a look into that and I will add some time measurement stuff to create a proper sorting performance benchmark ;)

Great, as soon as we have a test+benchmark, we can work on ironing out the last details and make sure that this can go into master.

Two small remarks:

1. I see the function expandedParentsCountCompare() in your diff. This function does not exist any more in master - you might want to rebase your diff on current master.

2. Concerning the "Avoid some unnecessary lessThan calls" idea: this actually makes your timsort function *much* harder to use. In version 1 of your patch, the function could easily be used as a drop-in replacement for std::sort, std::stable_sort, qSort, etc. by everyone who wants to use TimSort. This is no longer the case in version 2. Does this change improve the performance considerably? If that is not the case, I think that we should not make the function harder to use just to save a few microseconds.

- Frank Reininghaus


On Feb. 16, 2013, 6:19 p.m., Emmanuel Pescosta wrote:
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> http://git.reviewboard.kde.org/r/108824/
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> 
> (Updated Feb. 16, 2013, 6:19 p.m.)
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> 
> Review request for Dolphin and Frank Reininghaus.
> 
> 
> Description
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> 
> Implemented a new sorting algorithm called Tim Sort which is a modified Merge Sort algorithm (http://svn.python.org/projects/python/trunk/Objects/listsort.txt) - Default sorting algorithm in Python and Java
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> Tim Sort is really fast for already sorted lists (Great for inserting new items, sort role changes - see benchmark 2, ...)
> 
> Some benchmarks (200k folders and files):
> # Sort Type: Name => TimSort: 1755 ms - Parallel MergeSort: 1547 ms
> # Sort Type: Name (Reorder descending) => TimSort: 163 ms - Parallel MergeSort: 434 ms
> # Sort Type: Size => TimSort: 259 ms - Parallel MergeSort: 516 ms
> # Sort Type: Type => TimSort: 269 ms - Parallel MergeSort: 594 ms
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> Btw.: Tim Sort uses only 1 core!
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> ToDo: Write a benchmark for sorting algorithms
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> 
> Diffs
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>   dolphin/src/kitemviews/kfileitemmodel.h 903291a 
>   dolphin/src/kitemviews/kfileitemmodel.cpp a763b3f 
>   dolphin/src/kitemviews/private/kfileitemmodelsortalgorithm.h 1d56894 
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> Diff: http://git.reviewboard.kde.org/r/108824/diff/
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> 
> Testing
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> Sorting works fine for me
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> 
> Thanks,
> 
> Emmanuel Pescosta
> 
>

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