[LUCENE-10657] CopyBytes now saves one memory copy on ByteBuffersDataOutput

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 9.3
• Component/s: core/store
• Lucene Fields: New
• Assignee: Unassigned
• Reporter: LuYunCheng
• Created: 18/Jul/22 11:46
• Updated: 28/Aug/22 16:43
• Resolved: 19/Jul/22 07:52

Description

This is derived from [LUCENE-10627|https://github.com/apache/lucene/pull/987]

Code: 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 ByteBuffersDataOutput.blocks, i think there is unnecessary, we can override it, copy directly from input into output.

with override this method,

1. Reduce memory copy in `Lucene90CompressingStoredFieldsWriter#copyOneDoc` -> `bufferdDocs.copyBytes(DataInput input)`
2. Reduce memory copy in `Lucene90CompoundFormat.writeCompoundFile` -> `data.copyBytes` when input is `BufferedChecksumIndexinput` and output is `ByteBuffersDataOutput`
3. Reduce memory `IndexWriter#copySegmentAsIs` ->CopyFrom -> copyBytes

 
 

Issue Links

• links to: GitHub Pull Request #1034