• Kirill Smelkov's avatar
    golang_str: Speedup utf-8 decoding a bit on py2 · 9cb7b210
    Kirill Smelkov authored
    We recently moved our custom UTF-8 encoding/decoding routines to Cython.
    Now we can start taking speedup advantage on C level to make our own
    UTF-8 decoder a bit less horribly slow on py2:
        name       old time/op  new time/op  delta
        stddecode   752ns ± 0%   743ns ± 0%   -1.19%  (p=0.000 n=9+10)
        udecode     216µs ± 0%    75µs ± 0%  -65.19%  (p=0.000 n=9+10)
        stdencode   328ns ± 2%   327ns ± 1%     ~     (p=0.252 n=10+9)
        bencode    34.1µs ± 1%  32.1µs ± 1%   -5.92%  (p=0.000 n=10+10)
    So it is ~ 3x speedup for u(), but still significantly slower compared
    to std unicode.decode('utf-8').
    Only low-hanging fruit here to make _utf_decode_rune a bit more prompt,
    since it sits in the most inner loop. In the future
    _utf8_decode_surrogateescape might be reworked as well to avoid
    constructing resulting unicode via py-level list of py-unicode character
    objects. And similarly for _utf8_encode_surrogateescape.
    On py3 the performance of std and u/b decode/encode is approximately the same.
    /trusted-by @jerome
    /reviewed-on !19