romshark / datapages / 37689647710

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github

perf: Stop copying strings written to responses

The writers that wrap a response have no WriteString,
which makes io.WriteString copy every string into a new slice.
offline.Middleware also hides ReadFrom,
which http.FileServer uses for sendfile.

Allocations per request:

    example/counter GET /                            27 -> 19
    offline.Middleware, page of 22 WriteString       35 -> 14
    offline.Middleware, 30 KB script via FileServer  18 -> 17

ReadFrom forwards only a response that passes through.
A page still copies through Write, which decides on its first bytes
and commits no status before the source produces a byte.

36 of 36 new or added lines in 3 files covered. (100.0%)

16290 of 36848 relevant lines covered (44.21%)

583.45 hits per line