Use HPACK spelling for HTTP/2 compression#2271
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When compression is enforced, the request factory creates the default Accept-Encoding value as "gzip,deflate" for HTTP/1 compatibility. HTTP/2's HPACK static table contains "gzip, deflate", so the H2 frame writer missed the compact static entry for the generated default. Rewrite only the generated default while copying headers into HTTP/2 frames. User-supplied Accept-Encoding values keep their original spelling, and HTTP/1 output remains unchanged. Codex on behalf of Pavel Ptashyts Co-Authored-By: Codex <codex@openai.com>
Add a deterministic encoder test proving that the HPACK static-table spelling uses a one-byte indexed representation while the old spelling requires a literal value. Clarify that the JMH benchmark reports execution time and allocation; its return value prevents dead-code elimination but is not a separate JMH metric. Codex on behalf of Pavel Ptashyts Co-Authored-By: Codex <codex@openai.com>
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Replace the remaining non-ASCII punctuation in the touched HPACK benchmark so the source follows the repository guidelines in AGENTS.md. Codex on behalf of Pavel Ptashyts Co-Authored-By: Codex <codex@openai.com>
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Summary
Accept-Encodingvalue fromgzip,deflatetogzip, deflatewhile copying headers into HTTP/2 framesAccept-Encodingspelling and leave HTTP/1 output unchangedPerformance evidence
With Netty 4.2.15.Final and a fresh HPACK encoder:
gzip,deflate: 14 encoded bytesgzip, deflate: 1 encoded byte through the indexed static-table representationA short JMH validation on JDK 21 with
-prof gcmeasured 1032 B/op for the literal spelling and 680 B/op for the static-table spelling. Timing was noisy, so this PR relies on the deterministic wire-size test rather than claiming a stable CPU improvement.Validation
./mvnw -pl client -Dtest='org.asynchttpclient.netty.request.AcceptEncodingHpackTest,org.asynchttpclient.BasicHttp2Test#generatedAcceptEncodingUsesHpackStaticValueOverHttp2+userAcceptEncodingSpellingIsPreservedOverHttp2' test(3 tests)AcceptEncodingHpackBenchmark -f 1 -wi 3 -i 5 -w 500ms -r 500ms -prof gcBasicHttp2Testvalidation from the initial changeAttribution
Codex on behalf of Pavel Ptashyts