benchmark block - a prototype to benchmark a block without the block overhead

benchmark-block

#!/usr/bin/env ruby

private def benchmark(name = nil, &block)
  raise "needs a block" unless block
  binding = block.binding

  file, line = block.source_location
  start_line = line - 1
  lines = File.readlines(file)
  indent = lines.fetch(start_line)[/^(\s+)/, 1]
  end_line = start_line + 1
  until lines[end_line] =~ /^#{indent}end/
    unless lines[end_line] =~ /^#{indent}/
      raise "Line #{end_line+1} doesn't start with #{indent.inspect}: #{lines[end_line].inspect}"
    end
    end_line += 1
  end
  code = lines[start_line+1...end_line].join("\n").strip

  unless name
    vars = binding.local_variables.select { |var| code =~ /\b#{Regexp.escape var}\b/ }
    if vars.empty?
      name = code
    else
      pairs = vars.map { |var| [var, binding.local_variable_get(var).inspect] }.to_h
      # name = "#{code} with #{pairs.map { |k,v| "#{k}=#{v}" }.join(", ")}"
      name = code
      pairs.each_pair do |var, value|
        name = name.gsub(/\b#{Regexp.escape var}\b/, value)
      end
    end
  end

  STDOUT.print "#{name}    "
  STDOUT.flush

  timings = binding.eval <<-RUBY
  i = 0
  timings = []
  while i < 5 # TODO warmup, inner loop, etc
    t0 = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    #{code}
    t1 = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    timings << (t1 - t0)
    i += 1
  end
  timings
  RUBY

  avg = timings.sum / timings.size
  ips = 1.0 / avg
  STDOUT.puts "#{"%.3f" % ips} i/s    (#{"%.3f" % avg}s/i)"
end

ARGV.each { |arg| Kernel.load(arg) }

fib.rb

def fib n
  if n < 3
    1
  else
    fib(n-1) + fib(n-2)
  end
end

(28..32).each do |n|
  benchmark do
    fib(n)
  end
end

output.txt

$ ./benchmark-block fib.rb
fib(28)    72.505 i/s    (0.014s/i)
fib(29)    44.902 i/s    (0.022s/i)
fib(30)    27.826 i/s    (0.036s/i)
fib(31)    17.258 i/s    (0.058s/i)
fib(32)    10.591 i/s    (0.094s/i)