Feature #12788: Improve String lstrip and strip performance

• Status: Closed
• Assignee: -
• Target version: -

[asterite (Ary Borenszweig)]

This adds a fast path for lstrip_offset in the case of single byte optimizable strings. This optimization already exists in rstrip_offset but I noticed it was missing in rstrip.

I made sure to only remove ascii space, not '\0', to preserve backwards compatibility. (rstrip seems to remove '\0', but not lstrip)

A benchmark:

s = " " * 10_000_000
time = Time.now
p s.lstrip
p s.strip
puts Time.now - time

s = " " * 100_000_000
time = Time.now
p s.lstrip
p s.strip
puts Time.now - time

Times before: 0.195159 and 1.918969
Times after: 0.013684 and 0.143966

So a bit more than 10x faster.

By the way, Akira Matsuda-san gave a really nice closing keynote in RubyConf Brasil yesterday that encouraged all of us to use Ruby and contribute to it, so here is my first patch :-)

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset r56250.

---

string.c: fast path of lstrip_offset

• string.c (lstrip_offset): add a fast path in the case of single
  byte optimizable strings, as well as rstrip_offset.
  [ruby-core:77392] [Feature #12788]

[asterite (Ary Borenszweig)]

Thank you Nobu-san for reviewing and accepting this. Matsuda-san also mentioned a "patch monster" in his talk, I think now I know what he means :-)

[matsuda (Akira Matsuda)]

Ary Borenszweig wrote:

Thank you Nobu-san for reviewing and accepting this. Matsuda-san also mentioned a "patch monster" in his talk, I think now I know what he means :-)

🤘🏻