Feature #19287: Let DelegateClass respect the original method's arity in case of 0

• Status: Open
• Assignee: -
• Target version: -

[matsuda (Akira Matsuda)]

As reported in #19165, method delegation with *, **, and ... adds some overhead for a method that takes no argument. And current implementation of delegations in forwardable and delegate basically define all methods to take splat parameters.

But, with regard to DelegateClass, we can investigate the arity of the target methods in the initializer, then we can define the delegation method not to take the splat for zero arity methods.

A benchmark on trunk today results in 37% runtime performance improvement on a such method.

Benchmark:
Warming up --------------------------------------
old 551.697k i/100ms
new 721.906k i/100ms
Calculating -------------------------------------
old 6.511M (± 0.8%) i/s - 33.102M in 5.084530s
new 8.925M (± 1.0%) i/s - 44.758M in 5.015619s

Comparison:
new: 8924652.2 i/s
old: 6510691.1 i/s - 1.37x (± 0.00) slower

Patch: https://github.com/ruby/ruby/pull/7045

[matsuda (Akira Matsuda)]

I should have posted the patch to delegate's own repo. Reposted the same patch to https://github.com/ruby/delegate/pull/16

[jeremyevans0 (Jeremy Evans)]

• Tracker changed from Bug to Feature
• ruby -v deleted (ruby 3.3.0dev (2022-12-28T16:43:05Z master cada537040) +YJIT [arm64-darwin21])
• Backport deleted (2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN)