Small speedups to DocumentsWriter's quickSort

• Key: LUCENE-1211
• Type: Bug
• Status: Closed
• Resolution: Fixed
• Priority: Minor
• Assignee: Michael McCandless
• Reporter: Michael McCandless
• Component/s: Index
• Affects Version/s: 2.3, 2.3.1
• Fix Version/s: 2.4

Description

In working on LUCENE-510 I found that DocumentsWriter's quickSort can
be further optimized to handle the common case of sorting only 2
values.

I ran with this alg:

analyzer=org.apache.lucene.analysis.standard.StandardAnalyzer

doc.maker=org.apache.lucene.benchmark.byTask.feeds.LineDocMaker

docs.file=/Volumes/External/lucene/wiki.txt
doc.stored = true
doc.term.vector = true
doc.add.log.step=2000
doc.maker.forever = false

directory=FSDirectory
autocommit=false
compound=false

ram.flush.mb=64

{ "Rounds"
ResetSystemErase
{ "BuildIndex"
CreateIndex

{ "AddDocs" AddDoc > : 200000 - CloseIndex }

NewRound
} : 5

RepSumByPrefRound BuildIndex

Best of 5 was 857.3 docs/sec before the optimization and 881.6 after =
2.8% speedup, on a quad-core Mac Pro with 4-drive RAID 0 array.

The fix is trivial. I will commit shortly.