Optimize DelegateClass using `...` delegation by byroot · Pull Request #46 · ruby/delegate

byroot · 2025-11-15T10:15:33Z

By generating source code for methods that use ... delegation when possible, we can lower the overhead of delegation by half.

This could be lowered further by copying the delegated method signature, like in #16, but this would assume the delegated method signature never change, so I'm not sure if that's OK.

Then most of the remaining overhead is in calling __getobj__, but that's part of the spec, so can't be eliminated.

Results:

== no arguments ==
ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24]
Warming up --------------------------------------
baseline 3.838M i/100ms
handrolled 3.465M i/100ms
DelegateClass 979.160k i/100ms
Opt 2.028M i/100ms
Calculating -------------------------------------
baseline 64.296M (± 0.5%) i/s (15.55 ns/i) - 322.355M in 5.013724s
handrolled 57.058M (± 0.4%) i/s (17.53 ns/i) - 287.567M in 5.039966s
DelegateClass 12.118M (± 0.5%) i/s (82.52 ns/i) - 60.708M in 5.009812s
Opt 27.764M (± 0.5%) i/s (36.02 ns/i) - 139.925M in 5.039997s
Comparison:
baseline: 64296345.8 i/s
handrolled: 57058063.8 i/s - 1.13x slower
Opt: 27763713.5 i/s - 2.32x slower
DelegateClass: 12118085.0 i/s - 5.31x slower
== many arguments ==
ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24]
Warming up --------------------------------------
baseline 3.605M i/100ms
handrolled 3.275M i/100ms
DelegateClass 623.030k i/100ms
Opt 1.348M i/100ms
Calculating -------------------------------------
baseline 63.349M (± 1.6%) i/s (15.79 ns/i) - 317.272M in 5.009667s
handrolled 56.277M (± 0.2%) i/s (17.77 ns/i) - 281.623M in 5.004270s
DelegateClass 7.079M (± 4.1%) i/s (141.26 ns/i) - 35.513M in 5.026286s
Opt 17.953M (± 0.1%) i/s (55.70 ns/i) - 90.345M in 5.032248s
Comparison:
baseline: 63348844.0 i/s
handrolled: 56276912.5 i/s - 1.13x slower
Opt: 17953308.5 i/s - 3.53x slower
DelegateClass: 7079118.4 i/s - 8.95x slower

Benchmark:

require"delegate"require"bundler/inline"gemfiledogem"benchmark-ips"endclassUserattr_accessor:namedefinitialize(name)@name=nameenddefdo_something(a,b,c,d: 1):somethingendendclassHandrolledDelegatordefinitialize(user)@user=userenddefname@user.nameenddefdo_something(a,b,c,d: 1)@user.do_something(a,b,c,d: 1)endendStdlibDelegator=DelegateClass(User)defOptDelegateClass(superclass, &block)klass=Class.new(Delegator)ignores=[*::Delegator.public_api,:to_s,:inspect,:=~,:!~,:===]protected_instance_methods=superclass.protected_instance_methodsprotected_instance_methods -= ignorespublic_instance_methods=superclass.public_instance_methodspublic_instance_methods -= ignoresinstance_methods=(public_instance_methods + protected_instance_methods)normal,special=instance_methods.partition{ |m| m.match?(/\A[a-zA-Z]\w*\z/)}source=normal.mapdo |method|
"def #{method}(...); __getobj__.#{method}(...); end"endklass.module_evaldodef__getobj__# :nodoc:unlessdefined?(@delegate_dc_obj)returnyieldifblock_given?__raise__ ::ArgumentError,"not delegated"end@delegate_dc_objenddef__setobj__(obj)# :nodoc:__raise__ ::ArgumentError,"cannot delegate to self"ifself.equal?(obj)@delegate_dc_obj=objendclass_eval(source.join(";"),__FILE__,__LINE__)special.eachdo |method|
define_method(method,Delegator.delegating_block(method))endprotected(*protected_instance_methods)endklass.define_singleton_method:public_instance_methodsdo |all=true|
super(all) | superclass.public_instance_methodsendklass.define_singleton_method:protected_instance_methodsdo |all=true|
super(all) | superclass.protected_instance_methodsendklass.define_singleton_method:instance_methodsdo |all=true|
super(all) | superclass.instance_methodsendklass.define_singleton_method:public_instance_methoddo |name|
super(name)rescueNameErrorraiseunlessself.public_instance_methods.include?(name)superclass.public_instance_method(name)endklass.define_singleton_method:instance_methoddo |name|
super(name)rescueNameErrorraiseunlessself.instance_methods.include?(name)superclass.instance_method(name)endklass.module_eval(&block)ifblockreturnklassendOptStdlibDelegator=OptDelegateClass(User)direct=User.new("George")handrolled=HandrolledDelegator.new(direct)stdlib=StdlibDelegator.new(direct)opt_stdlib=OptStdlibDelegator.new(direct)puts"== no arguments =="Benchmark.ipsdo |x|
x.report("baseline"){direct.name}x.report("handrolled"){handrolled.name}x.report("DelegateClass"){stdlib.name}x.report("Opt"){opt_stdlib.name}x.compare!(order: :baseline)endputs"== many arguments =="Benchmark.ipsdo |x|
x.report("baseline"){direct.do_something(1,2,3,d: 4)}x.report("handrolled"){handrolled.do_something(1,2,3,d: 4)}x.report("DelegateClass"){stdlib.do_something(1,2,3,d: 4)}x.report("Opt"){opt_stdlib.do_something(1,2,3,d: 4)}x.compare!(order: :baseline)end

@name

Fix: rails#56167 I opened ruby/delegate#46 upstream to improve `ClassDelegator` but it has a bunch of backward compatibility concerns that limits how much it can be optimized. For internal use cases, we can define our own private class delegator and optimize it much further. ``` == no arguments == ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24] Warming up -------------------------------------- DelegateClass 1.014M i/100ms Opt 3.273M i/100ms Calculating ------------------------------------- DelegateClass 12.322M (± 0.8%) i/s (81.15 ns/i) - 61.838M in 5.018661s Opt 56.866M (± 0.4%) i/s (17.59 ns/i) - 284.716M in 5.006894s Comparison: DelegateClass: 12322457.6 i/s Opt: 56865721.7 i/s - 4.61x faster == many arguments == ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24] Warming up -------------------------------------- DelegateClass 555.419k i/100ms Opt 3.214M i/100ms Calculating ------------------------------------- DelegateClass 6.256M (± 0.6%) i/s (159.85 ns/i) - 31.659M in 5.060874s Opt 53.902M (± 0.0%) i/s (18.55 ns/i) - 269.936M in 5.007857s Comparison: DelegateClass: 6255815.2 i/s Opt: 53902461.2 i/s - 8.62x faster == optional arguments == ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24] Warming up -------------------------------------- DelegateClass 826.558k i/100ms Opt 1.645M i/100ms Calculating ------------------------------------- DelegateClass 9.821M (± 0.8%) i/s (101.82 ns/i) - 49.593M in 5.049895s Opt 21.177M (± 0.8%) i/s (47.22 ns/i) - 106.952M in 5.050788s Comparison: DelegateClass: 9821329.7 i/s Opt: 21176752.0 i/s - 2.16x faster ``` Benchmark: ```ruby require "delegate" require "bundler/inline" gemfile do gem "benchmark-ips" gem "rails", path: "." end class User attr_accessor :name def initialize(name) @name = name end def do_something(a, b, c, d:) :something end def opt_args(a=1, b: 2) :something end end StdlibDelegator = DelegateClass(User) ASDelegator = ActiveSupport::Delegation::DelegateClass(User) direct = User.new("George") stdlib = StdlibDelegator.new(direct) opt = ASDelegator.new(direct) puts "== no arguments ==" Benchmark.ips do |x| x.report("DelegateClass") { stdlib.name } x.report("Opt") { opt.name } x.compare!(order: :baseline) end puts "== many arguments ==" Benchmark.ips do |x| x.report("DelegateClass") { stdlib.do_something(1, 2, 3, d: 4) } x.report("Opt") { opt.do_something(1, 2, 3, d: 4) } x.compare!(order: :baseline) end puts "== optional arguments ==" Benchmark.ips do |x| x.report("DelegateClass") { stdlib.opt_args } x.report("Opt") { opt.opt_args } x.compare!(order: :baseline) end ```

@name

Fix: rails#56167 I opened ruby/delegate#46 upstream to improve `ClassDelegator` but it has a bunch of backward compatibility concerns that limits how much it can be optimized. For internal use cases, we can define our own private class delegator and optimize it much further. ``` == no arguments == ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24] Warming up -------------------------------------- DelegateClass 1.014M i/100ms Opt 3.273M i/100ms Calculating ------------------------------------- DelegateClass 12.322M (± 0.8%) i/s (81.15 ns/i) - 61.838M in 5.018661s Opt 56.866M (± 0.4%) i/s (17.59 ns/i) - 284.716M in 5.006894s Comparison: DelegateClass: 12322457.6 i/s Opt: 56865721.7 i/s - 4.61x faster == many arguments == ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24] Warming up -------------------------------------- DelegateClass 555.419k i/100ms Opt 3.214M i/100ms Calculating ------------------------------------- DelegateClass 6.256M (± 0.6%) i/s (159.85 ns/i) - 31.659M in 5.060874s Opt 53.902M (± 0.0%) i/s (18.55 ns/i) - 269.936M in 5.007857s Comparison: DelegateClass: 6255815.2 i/s Opt: 53902461.2 i/s - 8.62x faster == optional arguments == ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24] Warming up -------------------------------------- DelegateClass 826.558k i/100ms Opt 1.645M i/100ms Calculating ------------------------------------- DelegateClass 9.821M (± 0.8%) i/s (101.82 ns/i) - 49.593M in 5.049895s Opt 21.177M (± 0.8%) i/s (47.22 ns/i) - 106.952M in 5.050788s Comparison: DelegateClass: 9821329.7 i/s Opt: 21176752.0 i/s - 2.16x faster ``` Benchmark: ```ruby require "delegate" require "bundler/inline" gemfile do gem "benchmark-ips" gem "rails", path: "." end class User attr_accessor :name def initialize(name) @name = name end def do_something(a, b, c, d:) :something end def opt_args(a=1, b: 2) :something end end StdlibDelegator = DelegateClass(User) ASDelegator = ActiveSupport::Delegation::DelegateClass(User) direct = User.new("George") stdlib = StdlibDelegator.new(direct) opt = ASDelegator.new(direct) puts "== no arguments ==" Benchmark.ips do |x| x.report("DelegateClass") { stdlib.name } x.report("Opt") { opt.name } x.compare!(order: :baseline) end puts "== many arguments ==" Benchmark.ips do |x| x.report("DelegateClass") { stdlib.do_something(1, 2, 3, d: 4) } x.report("Opt") { opt.do_something(1, 2, 3, d: 4) } x.compare!(order: :baseline) end puts "== optional arguments ==" Benchmark.ips do |x| x.report("DelegateClass") { stdlib.opt_args } x.report("Opt") { opt.opt_args } x.compare!(order: :baseline) end ```

BuonOmo · 2025-11-18T11:30:48Z

 public_instance_methods -= ignores
+
+ instance_methods = (public_instance_methods + protected_instance_methods)
+ normal, special = instance_methods.partition { |m| m.match?(/\A[a-zA-Z]\w*!?\z/) }


Suggested change
normal,special=instance_methods.partition{ |m| m.match?(/\A[a-zA-Z]\w*!?\z/)}
normal,special=instance_methods.partition{ |m| m.match?(/\A[a-zA-Z]\w*[!?]?\z/)}
Il also saw that in the rails patch you used \w+ rather than \w*, IDK if there is a good reason for that

in the rails patch you used \w+ rather than \w*, IDK if there is a good reason for that
It's a mistake, \w* is correct.

@name

By generating source code for methods that use `...` delegation when possible, we can lower the overhead of delegation by half. This could be lowered further by copying the delegated method signature, like in ruby#16, but this would assume the delegated method signature never change, so I'm not sure if that's OK. Then most of the remaining overhead is in calling `__getobj__`, but that's part of the spec, so can't be eliminated. Results: ``` == no arguments == ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24] Warming up -------------------------------------- baseline 3.838M i/100ms handrolled 3.465M i/100ms DelegateClass 979.160k i/100ms Opt 2.028M i/100ms Calculating ------------------------------------- baseline 64.296M (± 0.5%) i/s (15.55 ns/i) - 322.355M in 5.013724s handrolled 57.058M (± 0.4%) i/s (17.53 ns/i) - 287.567M in 5.039966s DelegateClass 12.118M (± 0.5%) i/s (82.52 ns/i) - 60.708M in 5.009812s Opt 27.764M (± 0.5%) i/s (36.02 ns/i) - 139.925M in 5.039997s Comparison: baseline: 64296345.8 i/s handrolled: 57058063.8 i/s - 1.13x slower Opt: 27763713.5 i/s - 2.32x slower DelegateClass: 12118085.0 i/s - 5.31x slower == many arguments == ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24] Warming up -------------------------------------- baseline 3.605M i/100ms handrolled 3.275M i/100ms DelegateClass 623.030k i/100ms Opt 1.348M i/100ms Calculating ------------------------------------- baseline 63.349M (± 1.6%) i/s (15.79 ns/i) - 317.272M in 5.009667s handrolled 56.277M (± 0.2%) i/s (17.77 ns/i) - 281.623M in 5.004270s DelegateClass 7.079M (± 4.1%) i/s (141.26 ns/i) - 35.513M in 5.026286s Opt 17.953M (± 0.1%) i/s (55.70 ns/i) - 90.345M in 5.032248s Comparison: baseline: 63348844.0 i/s handrolled: 56276912.5 i/s - 1.13x slower Opt: 17953308.5 i/s - 3.53x slower DelegateClass: 7079118.4 i/s - 8.95x slower ``` Benchmark: ```ruby require "delegate" require "bundler/inline" gemfile do gem "benchmark-ips" end class User attr_accessor :name def initialize(name) @name = name end def do_something(a, b, c, d: 1) :something end end class HandrolledDelegator def initialize(user) @user = user end def name @user.name end def do_something(a, b, c, d: 1) @user.do_something(a, b, c, d: 1) end end StdlibDelegator = DelegateClass(User) def OptDelegateClass(superclass, &block) klass = Class.new(Delegator) ignores = [*::Delegator.public_api, :to_s, :inspect, :=~, :!~, :===] protected_instance_methods = superclass.protected_instance_methods protected_instance_methods -= ignores public_instance_methods = superclass.public_instance_methods public_instance_methods -= ignores instance_methods = (public_instance_methods + protected_instance_methods) normal, special = instance_methods.partition { |m| m.match?(/\A[a-zA-Z]\w*\z/) } source = normal.map do |method| "def #{method}(...); __getobj__.#{method}(...); end" end klass.module_eval do def __getobj__ # :nodoc: unless defined?(@delegate_dc_obj) return yield if block_given? __raise__ ::ArgumentError, "not delegated" end @delegate_dc_obj end def __setobj__(obj) # :nodoc: __raise__ ::ArgumentError, "cannot delegate to self" if self.equal?(obj) @delegate_dc_obj = obj end class_eval(source.join(";"), __FILE__, __LINE__) special.each do |method| define_method(method, Delegator.delegating_block(method)) end protected(*protected_instance_methods) end klass.define_singleton_method :public_instance_methods do |all=true| super(all) | superclass.public_instance_methods end klass.define_singleton_method :protected_instance_methods do |all=true| super(all) | superclass.protected_instance_methods end klass.define_singleton_method :instance_methods do |all=true| super(all) | superclass.instance_methods end klass.define_singleton_method :public_instance_method do |name| super(name) rescue NameError raise unless self.public_instance_methods.include?(name) superclass.public_instance_method(name) end klass.define_singleton_method :instance_method do |name| super(name) rescue NameError raise unless self.instance_methods.include?(name) superclass.instance_method(name) end klass.module_eval(&block) if block return klass end OptStdlibDelegator = OptDelegateClass(User) direct = User.new("George") handrolled = HandrolledDelegator.new(direct) stdlib = StdlibDelegator.new(direct) opt_stdlib = OptStdlibDelegator.new(direct) puts "== no arguments ==" Benchmark.ips do |x| x.report("baseline") { direct.name } x.report("handrolled") { handrolled.name } x.report("DelegateClass") { stdlib.name } x.report("Opt") { opt_stdlib.name } x.compare!(order: :baseline) end puts "== many arguments ==" Benchmark.ips do |x| x.report("baseline") { direct.do_something(1, 2, 3, d: 4) } x.report("handrolled") { handrolled.do_something(1, 2, 3, d: 4) } x.report("DelegateClass") { stdlib.do_something(1, 2, 3, d: 4) } x.report("Opt") { opt_stdlib.do_something(1, 2, 3, d: 4) } x.compare!(order: :baseline) end ```

This reverts commit 2420b69, reversing changes made to 244c2c9.

This reverts commit fc2bd04.

This reverts commit fc2bd04. Co-authored-by: Jean Boussier <byroot@ruby-lang.org>

Reapply "Merge pull request #46 from byroot/use-forward-send"

This reverts commit fc2bd04. Co-authored-by: Jean Boussier <byroot@ruby-lang.org>

@name

Fix: rails#56167 I opened ruby/delegate#46 upstream to improve `ClassDelegator` but it has a bunch of backward compatibility concerns that limits how much it can be optimized. For internal use cases, we can define our own private class delegator and optimize it much further. ``` == no arguments == ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24] Warming up -------------------------------------- DelegateClass 1.014M i/100ms Opt 3.273M i/100ms Calculating ------------------------------------- DelegateClass 12.322M (± 0.8%) i/s (81.15 ns/i) - 61.838M in 5.018661s Opt 56.866M (± 0.4%) i/s (17.59 ns/i) - 284.716M in 5.006894s Comparison: DelegateClass: 12322457.6 i/s Opt: 56865721.7 i/s - 4.61x faster == many arguments == ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24] Warming up -------------------------------------- DelegateClass 555.419k i/100ms Opt 3.214M i/100ms Calculating ------------------------------------- DelegateClass 6.256M (± 0.6%) i/s (159.85 ns/i) - 31.659M in 5.060874s Opt 53.902M (± 0.0%) i/s (18.55 ns/i) - 269.936M in 5.007857s Comparison: DelegateClass: 6255815.2 i/s Opt: 53902461.2 i/s - 8.62x faster == optional arguments == ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24] Warming up -------------------------------------- DelegateClass 826.558k i/100ms Opt 1.645M i/100ms Calculating ------------------------------------- DelegateClass 9.821M (± 0.8%) i/s (101.82 ns/i) - 49.593M in 5.049895s Opt 21.177M (± 0.8%) i/s (47.22 ns/i) - 106.952M in 5.050788s Comparison: DelegateClass: 9821329.7 i/s Opt: 21176752.0 i/s - 2.16x faster ``` Benchmark: ```ruby require "delegate" require "bundler/inline" gemfile do gem "benchmark-ips" gem "rails", path: "." end class User attr_accessor :name def initialize(name) @name = name end def do_something(a, b, c, d:) :something end def opt_args(a=1, b: 2) :something end end StdlibDelegator = DelegateClass(User) ASDelegator = ActiveSupport::Delegation::DelegateClass(User) direct = User.new("George") stdlib = StdlibDelegator.new(direct) opt = ASDelegator.new(direct) puts "== no arguments ==" Benchmark.ips do |x| x.report("DelegateClass") { stdlib.name } x.report("Opt") { opt.name } x.compare!(order: :baseline) end puts "== many arguments ==" Benchmark.ips do |x| x.report("DelegateClass") { stdlib.do_something(1, 2, 3, d: 4) } x.report("Opt") { opt.do_something(1, 2, 3, d: 4) } x.compare!(order: :baseline) end puts "== optional arguments ==" Benchmark.ips do |x| x.report("DelegateClass") { stdlib.opt_args } x.report("Opt") { opt.opt_args } x.compare!(order: :baseline) end ```

byroot requested a review from hsbt November 15, 2025 10:15

byroot mentioned this pull request Nov 15, 2025
Replace TimeZoneConversion's DelegateClass rails/rails#56167
Closed

byroot force-pushed the use-forward-send branch from 22ee1ad to 5c8ab6cCompare November 15, 2025 10:18

byroot mentioned this pull request Nov 15, 2025
Faster class delegator rails/rails#56171
Merged

BuonOmo reviewed Nov 18, 2025
View reviewed changes

byroot force-pushed the use-forward-send branch from 5c8ab6c to b2293d4Compare November 18, 2025 18:31

hsbt approved these changes Dec 17, 2025
View reviewed changes

hsbt merged commit 2420b69 into ruby:masterDec 17, 2025
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hsbt added a commit that referenced this pull request Dec 17, 2025
Revert "Merge pull request#46from byroot/use-forward-send"
fc2bd04
This reverts commit 2420b69, reversing changes made to 244c2c9.

hsbt added a commit that referenced this pull request Dec 17, 2025
Reapply "Merge pull request#46from byroot/use-forward-send"
a2f023f
This reverts commit fc2bd04.

hsbt added a commit that referenced this pull request Dec 17, 2025
Reapply "Merge pull request#46from byroot/use-forward-send"
b0f401c
This reverts commit fc2bd04. Co-authored-by: Jean Boussier <byroot@ruby-lang.org>

hsbt mentioned this pull request Dec 17, 2025
Reapply "Merge pull request #46 from byroot/use-forward-send" #51
Merged

byroot added a commit that referenced this pull request Dec 17, 2025
Reapply "Merge pull request#46from byroot/use-forward-send"
119c58a
This reverts commit fc2bd04. Co-authored-by: Jean Boussier <byroot@ruby-lang.org>

byroot added a commit that referenced this pull request Dec 17, 2025
Reapply "Merge pull request#46from byroot/use-forward-send"
7d5c1e0
This reverts commit fc2bd04. Co-authored-by: Jean Boussier <byroot@ruby-lang.org>

hsbt added a commit that referenced this pull request Dec 18, 2025
Merge pull request#51from ruby/reapply-gh-46
d1c82ca
Reapply "Merge pull request #46 from byroot/use-forward-send"

hsbt added a commit to luke-gruber/delegate that referenced this pull request Dec 18, 2025
Reapply "Merge pull requestruby#46from byroot/use-forward-send"
ea601ee
This reverts commit fc2bd04. Co-authored-by: Jean Boussier <byroot@ruby-lang.org>

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Optimize DelegateClass using `...` delegation - #46

Optimize DelegateClass using `...` delegation#46
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	normal,special=instance_methods.partition{ \|m\| m.match?(/\A[a-zA-Z]\w*!?\z/)}
	normal,special=instance_methods.partition{ \|m\| m.match?(/\A[a-zA-Z]\w*[!?]?\z/)}

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