Looking for feedback on a possible inplace_stable_sort replacement

Marshall Clow mclow.lists at gmail.com
Tue Mar 18 08:37:53 PDT 2014

On Mar 13, 2014, at 11:06 AM, Mike McFadden <mike at ivideoapp.com> wrote:

> Hi, I used a paper called "Ratio based in-place stable merging" to implement a hybrid stable sort algorithm, and have been validating the results against stable_sort and inplace_stable_sort. What's interesting is that it matches 80-90% of the speed of stable_sort with random data, is much faster in many other cases, and does so while using O(1) memory. Simply giving it more memory allows it to closely match stable_sort in speed. And compared to inplace_stable_sort it's anywhere from 3-15x faster, with random data being about 5x faster.
> I have fully documented the algorithm and have a C++ implementation available here:
> https://github.com/BonzaiThePenguin/WikiSort
> The underlying algorithm was vetted and proven back in 2008 (there's a link to the published paper on the GitHub project page), and the simplified version used here is constantly tested against existing algorithms for correctness and speed, but toying with a core feature of libc++ is obviously not something to be taken lightly so I'm hoping for some additional vetting and consideration.
> My ultimate goal would be to replace inplace_stable_sort at the very least, and ideally stable_sort as well. Maybe including it as a separate sort function for now would be wise?

Mike —

I apologize for not getting back to you sooner.

I am quite interested in this proposal, and plan on looking at it closely … soon.
Right at the moment, I’m trying to get the last few bits for full C++14 compliance done in libc++.
Once that’s done, I’ll have cycles to look at this (and other things).

— Marshall

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