[jira] [Commented] (LUCENE-10619) Optimize the writeBytes in TermsHashPerField

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

    [ https://issues.apache.org/jira/browse/LUCENE-10619?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17555646#comment-17555646 ] 

Adrien Grand commented on LUCENE-10619:
---------------------------------------

This looks like an interesting idea!

> Optimize the writeBytes in TermsHashPerField
> --------------------------------------------
>
>                 Key: LUCENE-10619
>                 URL: https://issues.apache.org/jira/browse/LUCENE-10619
>             Project: Lucene - Core
>          Issue Type: Improvement
>          Components: core/index
>    Affects Versions: 9.2
>            Reporter: tangdh
>            Priority: Major
>
> Because we don't know the length of slice, writeBytes will always write byte one after another instead of writing a block of bytes.
> May be we could return both offset and length in ByteBlockPool#allocSlice?
> 1. BYTE_BLOCK_SIZE is 32768, offset is at most 15 bits.
> 2. slice size is at most 200, so it could fit in 8 bits.
> So we could put them together into an int -------- offset | length
> There are only two places where this function is used，the cost of change it is relatively small.
> When allocSlice could return the offset and length of new Slice, we could change writeBytes like below
> {code:java}
> // write block of bytes each time
> while(remaining > 0 ) {
>    int offsetAndLength = allocSlice(bytes, offset);
>    length = min(remaining, (offsetAndLength & 0xff) - 1);
>    offset = offsetAndLength >> 8;
>    System.arraycopy(src, srcPos, bytePool.buffer, offset, length);
>    remaining -= length;
>    offset    += (length + 1);
> }
> {code}
> If it could work, I'd like to raise a pr.



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