perf(tabix): reuse the line buffer across records (no per-record malloc) - #83
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…rd malloc TabixInputStream::fetch_next_line declared a fresh kstring_t on every call, so each record streamed through a bgzipped `-r` range query paid an htslib malloc + a free. Make the kstring a member reused across the whole scan (htslib's bgzf_getline resets its length and reallocs only when a line outgrows the buffer), freed once in the destructor. Output byte-identical (verified on a 1 M-record tabix BED); a small steady-state gain (~3% on that scan) and no per-record allocator churn. Suite 375. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Summary
TabixInputStream::fetch_next_linedeclared a freshkstring_ton every call, so each record streamed through a bgzipped-rrange query (VCF/BED/GFF/TSV.gz) paid an htslibmalloc+ afree. It now keeps one buffer for the whole scan — htslib'sbgzf_getlineresets the length and reallocs only when a line outgrows it — freed once in the destructor.Verification
-r chr1:1-3e7query over a 1 M-record tabix BED, old vs new.🤖 Generated with Claude Code