Compression: add zstd, switch backend to bytesrw, compress by default in serve mode#303
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balat wants to merge 6 commits into
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Compression: add zstd, switch backend to bytesrw, compress by default in serve mode#303balat wants to merge 6 commits into
balat wants to merge 6 commits into
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Replace the hand-written gzip framing (header, CRC32, trailer) and the camlzip Zlib calls with bytesrw writer filters. gzip and deflate (zlib format) behaviour is unchanged; the streaming model now bridges the synchronous bytesrw compressor to the Lwt output through an in-memory buffer flushed after each chunk.
Negotiate the "zstd" Content-Encoding (RFC 8878) alongside gzip and deflate, using bytesrw.zstd. zstd is preferred over gzip and deflate at equal qvalue.
Add a compression registry mirroring the static-server one. The Deflatemod extension publishes a compression instruction with safe defaults (text-based content types), loaded on demand by serve mode and applied after the file server. Matches the on-the-fly compression of `caddy file-server`.
Assert per-codec Content-Encoding (gzip, deflate, zstd) and the zstd preference in deflatemod.t, and that serve mode compresses by default.
Update the Deflatemod manual page for the zstd content-encoding, the codec preference order, the bytesrw dependency, the lack of a Brotli binding, and on-by-default compression in serve mode. Add a CHANGES entry.
Julow
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Jun 26, 2026
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Very nice! Do you have an idea of the changes in performances ?
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No :) |
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Summary
Improves Ocsigen Server's content compression, in the spirit of the recent
quick-wins bringing it closer to mainstream static servers (Caddy, nginx).
deflate, preferred at equal qvalue.
bytesrw(a single,modern, composable writer-filter abstraction for gzip/deflate/zstd). This
removes ~90 lines of hand-written gzip framing (header, CRC32, trailer) and
drops the camlzip dependency (it was used nowhere else).
(
ocsigenserver ./public), via a small registry mirroring the static-serverone, so it matches
caddy file-server.Brotli is intentionally not included: there is currently no maintained
OCaml 5 binding to libbrotli (the
brotliopam package requiresocaml < 4.10).Left as a follow-up.
Notes
deflatemaps to the zlib format (Bytesrw_zlib.Zlib), matching theprevious camlzip behaviour (it emitted a zlib header), not raw deflate.
bytesrw,conf-zlib,conf-zstd(system depexts:libzstd-dev,zlib1g-dev).Tests
deflatemod.t: per-codec Content-Encoding (gzip, deflate, zstd) and the zstdpreference.
serve.t: serve mode compresses by default.dune build @checkand@docare green.