Coverband cache ignored files benchmark

coverband-cache-ignored-files-benchmark.rb

require 'benchmark/ips'
require 'benchmark/memory'
require 'set'

SIZE = 10_000

FILES = Array.new(100) do
  dir = rand(2) == 1 ? Dir.pwd : '/other'
  dir << '/gems' unless rand(3) == 1
  name = [*('A'..'Z')].sample(8).join
  "#{dir}/#{name}"
end

def get_file
  FILES.sample
end

def get_number
  rand(200)
end

@ignore_patterns = ['internal:prelude', 'gems']
@project_directory = File.expand_path(Dir.pwd)
def track_file?(file)
  !@ignore_patterns.any?{ |pattern| file.include?(pattern) } && file.start_with?(@project_directory)
end

def reject
  track = {}
  SIZE.times do
    file = get_file
    n = get_number
    track[file] ||= Hash.new(0)
    track[file][n] += 1
  end
  track.reject!{|file, _lines| !track_file?(file) }
end

def without_cache
  track = {}
  SIZE.times do
    file = get_file
    n = get_number
    if track_file?(file)
      track[file] ||= Hash.new(0)
      track[file][n] += 1
    end
  end
end

def with_cache
  track = {}
  ignored = Set.new
  SIZE.times do
    file = get_file
    n = get_number
    if !ignored.include?(file)
      if track_file?(file)
        track[file] ||= Hash.new(0)
        track[file][n] += 1
      else
        ignored << file
      end
    end
  end
end

def benchmark(x)
  x.report("reject: ") { reject }
  x.report("without_cache: ") { without_cache }
  x.report("with_cache: ") { with_cache }

  x.compare!
end

Benchmark.memory(&method(:benchmark))
Benchmark.ips(&method(:benchmark))


# Results
# Memory Comparison:
#     without_cache: :      45392 allocated
#        with_cache: :      52216 allocated - 1.15x more
#            reject: :     413731 allocated - 9.11x more
#
# Speed Comparison:
#        with_cache: :      144.1 i/s
#     without_cache: :       86.1 i/s - 1.67x  slower
#            reject: :       79.4 i/s - 1.81x  slower