[jira] [Created] (LUCENE-4946) Refactor SorterTemplate

["Adrien Grand (JIRA)" <ji...@apache.org>]

Adrien Grand created LUCENE-4946:
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             Summary: Refactor SorterTemplate
                 Key: LUCENE-4946
                 URL: https://issues.apache.org/jira/browse/LUCENE-4946
             Project: Lucene - Core
          Issue Type: Improvement
            Reporter: Adrien Grand
            Assignee: Adrien Grand
            Priority: Trivial


When working on TimSort (LUCENE-4839), I was a little frustrated of not being able to add galloping support because it would have required to add new primitive operations in addition to compare and swap.

I started working on a prototype that uses inheritance to allow some sorting algorithms to rely on additional primitive operations. You can have a look at https://github.com/jpountz/sorts/tree/master/src/java/net/jpountz/sorts (but beware it is a prototype and still misses proper documentation and good tests).

I think it would offer several advantages:
 - no more need to implement setPivot and comparePivot when using in-place merge sort or insertion sort,
 - the ability to use faster stable sorting algorithms at the cost of some memory overhead (our in-place merge sort is very slow),
 - the ability to implement properly algorithms that are useful on specific datasets but require different primitive operations (such as TimSort for partially-sorted data).

If you are interested in comparing these implementations with Arrays.sort, there is a Benchmark class in src/examples.

What do you think?

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