elixir-gettext / gettext / 7cf265ab8a241d4d49ce8a7174504a511b3bb517-PR-450

94%

main: 94%

Pull #450

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

6 of 6 new or added lines in 1 file covered. (100.0%)

771 of 822 relevant lines covered (93.8%)

36.69 hits per line