[LUCENE-10661] Reduce memory copy in BytesStore

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 9.4
• Lucene Fields: New
• Assignee: Unassigned
• Reporter: LuYunCheng
• Created: 25/Jul/22 06:01
• Updated: 28/Aug/22 16:43
• Resolved: 27/Jul/22 14:19

Description

This is derived from LUCENE-10627(https://github.com/apache/lucene/pull/987) AND LUCENE-10657(https://github.com/apache/lucene/pull/1034)

The abstract method copyBytes in DataOutput have to copy from input to a copyBuffer and then write into BytesStore.blocks, which is called in FST initialization read from metaIn. 

Although, this copy bytes only a few bytes (in the testscase only 3-10 bytes), i think we can save this memory copy, just save the DataOutput.copyBytes to create new copyBuffer with 16384 bytes

Issue Links

• links to: GitHub Pull Request #1047