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Add benchmarks for threadsafe let block
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As requested in rspec#1858
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@JoshCheek
JoshCheek committed Feb 7, 2015
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require 'rspec/core'

# switches between these implementations - https://github.com/rspec/rspec-core/pull/1858/files
# benchmark requested in this PR - https://github.com/rspec/rspec-core/pull/1858
#
# I ran these by adding "benchmark-ips" to ../Gemfile
# then exported BUNDLE_GEMFILE to point t it
# then ran `bundle exec rspec threadsafe_let_block.rb`
class LetBlockImplementationHelper

MemoizedHelpers = ::RSpec::Core::MemoizedHelpers
Memoized = MemoizedHelpers::Memoized

def title(title)
hr = "#" * (title.length + 6)
blank = "# #{' ' * title.length} #"
[hr, blank, "# #{title} #", blank, hr]
end

def use_non_threadsafe
return if @state == :old
@state = :old
MemoizedHelpers.module_eval do
def subject
__memoized.fetch(:subject) do
__memoized[:subject] = begin
described = described_class || self.class.metadata.fetch(:description_args).first
Class === described ? described.new : described
end
end
end

def __memoized
@__memoized ||= {}
end
end

class << MemoizedHelpers::ContextHookMemoized
alias fetch for
end

MemoizedHelpers::ClassMethods.module_eval do
def let(name, &block)
# We have to pass the block directly to `define_method` to
# allow it to use method constructs like `super` and `return`.
raise "#let or #subject called without a block" if block.nil?
MemoizedHelpers.module_for(self).__send__(:define_method, name, &block)

# Apply the memoization. The method has been defined in an ancestor
# module so we can use `super` here to get the value.
if block.arity == 1
define_method(name) { __memoized.fetch(name) { |k| __memoized[k] = super(RSpec.current_example, &nil) } }
else
define_method(name) { __memoized.fetch(name) { |k| __memoized[k] = super(&nil) } }
end
end
end
end


def use_threadsafe
return if @state == :new
@state = :new
MemoizedHelpers.module_eval do
def subject
__memoized.for(:subject) do
described = described_class || self.class.metadata.fetch(:description_args).first
Class === described ? described.new : described
end
end

def __memoized
@__memoized ||= Memoized.new
end
end

MemoizedHelpers::ClassMethods.module_eval do
def let(name, &block)
# We have to pass the block directly to `define_method` to
# allow it to use method constructs like `super` and `return`.
raise "#let or #subject called without a block" if block.nil?
MemoizedHelpers.module_for(self).__send__(:define_method, name, &block)

# Apply the memoization. The method has been defined in an ancestor
# module so we can use `super` here to get the value.
if block.arity == 1
define_method(name) { __memoized.for(name) { super(RSpec.current_example, &nil) } }
else
define_method(name) { __memoized.for(name) { super(&nil) } }
end
end
end
end
end


require 'benchmark/ips'


# Given
# let(:name) { nil }
# how many iterations per second for
# my branch
# master
# when called
# once
# 10x
# Same thing with a call to super


helper = LetBlockImplementationHelper.new


puts helper.title "versions"
puts "RUBY_VERSION #{RUBY_VERSION}"
puts "ruby -v #{`ruby -v`}"
puts "Benchmark::IPS::VERSION #{Benchmark::IPS::VERSION}"
puts "rspec-core SHA #{`git log --pretty=format:%H -1`}"
puts


puts helper.title "1 call to let -- each sets the value"
Benchmark.ips do |x|
x.report("threadsafe") do |times|
helper.use_threadsafe
group = RSpec::Core::ExampleGroup.describe 'threadsafe1' do
let(:name) { nil }
times.times { example { name } }
end
raise "the run did not succeed!" unless group.run
end

x.report("non-threadsafe") do |times|
helper.use_non_threadsafe
group = RSpec::Core::ExampleGroup.describe 'non-threadsafe1' do
let(:name) { nil }
times.times { example { name } }
end
raise "the run did not succeed!" unless group.run
end

x.compare!
end


puts helper.title "10 calls to let -- 9 will find memoized value"
Benchmark.ips do |x|
x.report("threadsafe") do |times|
helper.use_threadsafe
group = RSpec::Core::ExampleGroup.describe 'threadsafe2' do
let(:name) { nil }
times.times { example { name; name; name; name; name; name; name; name; name; name; } }
end
raise "the run did not succeed!" unless group.run
end

x.report("non-threadsafe") do |times|
helper.use_non_threadsafe
group = RSpec::Core::ExampleGroup.describe 'non-threadsafe2' do
let(:name) { nil }
times.times { example { name; name; name; name; name; name; name; name; name; name; } }
end
raise "the run did not succeed!" unless group.run
end

x.compare!
end


puts helper.title "1 call to let which invokes super"
Benchmark.ips do |x|
x.report("threadsafe") do |times|
helper.use_threadsafe
group = RSpec::Core::ExampleGroup.describe 'threadsafe3' do
let(:name) { nil }
describe 'child' do
let(:name) { super() }
times.times { example { name } }
end
end
raise "the run did not succeed!" unless group.run
end

x.report("non-threadsafe") do |times|
helper.use_non_threadsafe
group = RSpec::Core::ExampleGroup.describe 'non-threadsafe3' do
let(:name) { nil }
describe 'child' do
let(:name) { super() }
times.times { example { name } }
end
end
raise "the run did not succeed!" unless group.run
end

x.compare!
end


puts helper.title "10 calls to let which invokes super"
Benchmark.ips do |x|
x.report("threadsafe") do |times|
helper.use_threadsafe
group = RSpec::Core::ExampleGroup.describe 'threadsafe4' do
let(:name) { nil }
describe 'child' do
let(:name) { super() }
times.times { example { name; name; name; name; name; name; name; name; name; name; } }
end
end
raise "the run did not succeed!" unless group.run
end

x.report("non-threadsafe") do |times|
helper.use_non_threadsafe
group = RSpec::Core::ExampleGroup.describe 'non-threadsafe4' do
let(:name) { nil }
describe 'child' do
let(:name) { super() }
times.times { example { name; name; name; name; name; name; name; name; name; name; } }
end
end
raise "the run did not succeed!" unless group.run
end

x.compare!
end


__END__

##############
# #
# versions #
# #
##############
RUBY_VERSION 2.2.0
ruby -v ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin13]
Benchmark::IPS::VERSION 2.1.1
rspec-core SHA 9daea3316b07736ac536f104d443d2f29e7ed722

##########################################
# #
# 1 call to let -- each sets the value #
# #
##########################################
Calculating -------------------------------------
threadsafe 120.000 i/100ms
non-threadsafe 121.000 i/100ms
-------------------------------------------------
threadsafe 7.949k (±19.7%) i/s - 35.760k
non-threadsafe 8.541k (±21.7%) i/s - 35.695k

Comparison:
non-threadsafe: 8541.2 i/s
threadsafe: 7948.8 i/s - 1.07x slower

###################################################
# #
# 10 calls to let -- 9 will find memoized value #
# #
###################################################
Calculating -------------------------------------
threadsafe 45.000 i/100ms
non-threadsafe 49.000 i/100ms
-------------------------------------------------
threadsafe 4.894k (±18.7%) i/s - 20.835k
non-threadsafe 5.603k (±17.8%) i/s - 23.128k

Comparison:
non-threadsafe: 5603.0 i/s
threadsafe: 4894.2 i/s - 1.14x slower

#######################################
# #
# 1 call to let which invokes super #
# #
#######################################
Calculating -------------------------------------
threadsafe 23.000 i/100ms
non-threadsafe 25.000 i/100ms
-------------------------------------------------
threadsafe 2.796k (±15.7%) i/s - 12.029k
non-threadsafe 3.313k (±13.3%) i/s - 14.200k

Comparison:
non-threadsafe: 3312.7 i/s
threadsafe: 2795.8 i/s - 1.18x slower

#########################################
# #
# 10 calls to let which invokes super #
# #
#########################################
Calculating -------------------------------------
threadsafe 18.000 i/100ms
non-threadsafe 18.000 i/100ms
-------------------------------------------------
threadsafe 2.283k (±12.3%) i/s - 9.684k
non-threadsafe 2.409k (±12.6%) i/s - 10.890k

Comparison:
non-threadsafe: 2408.8 i/s
threadsafe: 2283.1 i/s - 1.06x slower

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