akka/akka-http

Http2: Optimize HPACK header encoding for high entropy headers

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#2,892 建立於 2020年1月16日

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1 - triagedhackathonhelp wantedt:coret:http2t:performance

描述

As @surendarchandra noticed, our HPACK header tries to encode as many header values as possible into dynamic table entries. The effect can be that high entropy headers like Date or Content-Length evict more useful headers from the dynamic table.

The HPACK implementation from twitter that we use, allows to pass the sensitive flag to encodeHeader which prevents that the values are put into the dynamic table. We should consider to encode high entropy header using the sensitive flag for better use of the dynamic header table.

貢獻者指南

技術棧
scala
領域
backendperformance
議題類型
performance
難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。
3
預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。
half day
活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。
stale
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
clear
前置要求
HTTP/2 basicsHPACK encodingScala
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
30
研究方向
Investigate the HPACK implementation used (twitter hpack) and how encodeHeader is called in akka http. Identify high entropy headers like Date or Content Length that should be encoded with the sensitive flag. Review the existing code and comments, particularly the reference to @surendarchandra's observation. Modify the relevant call to pass the sensitive flag for those headers to prevent eviction of useful entries from the dynamic table.
Http2: Optimize HPACK header encoding for high entropy headers · akka/akka-http#2892 | Good First Issue