elixir-gettext / gettext / 180931cb6663d453f89d1d21cca16f7eb1d42bd4-PR-445

94%

main: 94%

Pull #445

github

Compile the interpolation patterns once per VM

to_interpolatable/1 compiled the "%{" and "}" patterns with
:binary.compile_pattern/1 on every call. Each compilation costs about as
much as splitting a short string, and this function runs on every runtime
interpolation: whenever the current locale has no translation for a
message, including every render in the default locale of an application
without a PO file for it, and once per message at compile time.

A compiled pattern is a reference, so it cannot live in a module attribute;
the two patterns are now compiled on first use and kept in persistent_term.
Passing the literal strings to :binary.split/2 instead would compile them
again on every split and gets slower as the number of bindings grows.

Microbenchmark of runtime_interpolate/2 (compiled loop, median of 7
alternating samples, Elixir 1.20.4 / OTP 29, one scheduler; OTP 27 within
5% of these):

    input                        before    after
    no bindings                  0.44 us   0.15 us
    1 binary binding             0.72 us   0.39 us
    3 binary bindings            1.06 us   0.78 us
    32 bindings                  7.76 us   7.27 us
    long text, 1 binding         0.75 us   0.45 us

10 of 10 new or added lines in 2 files covered. (100.0%)

759 of 810 relevant lines covered (93.7%)

38.04 hits per line