require 'benchmark/ips'
require 'redis'
class MethodProfiler
  def self.patch(klass, methods, name)
    patches = methods.map do |method_name|
      <<~RUBY
      unless defined?(#{method_name}__mp_unpatched)
        alias_method :#{method_name}__mp_unpatched, :#{method_name}
        def #{method_name}(*args, &blk)
          unless prof = Thread.current[:_method_profiler]
            return #{method_name}__mp_unpatched(*args, &blk)
          end
          begin
            start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
            #{method_name}__mp_unpatched(*args, &blk)
          ensure
            data = (prof[:#{name}] ||= {duration: 0.0, calls: 0})
            data[:duration] += Process.clock_gettime(Process::CLOCK_MONOTONIC) - start
            data[:calls] += 1
          end
        end
      end
      RUBY
    end.join("\n")

    klass.class_eval patches
  end

  def self.start
    Thread.current[:_method_profiler] = {
      __start: Process.clock_gettime(Process::CLOCK_MONOTONIC)
    }
  end

  def self.stop
    finish = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    if data = Thread.current[:_method_profiler]
      Thread.current[:_method_profiler] = nil
      start = data.delete(:__start)
      data[:total_duration] = finish - start
      data
    end
  end
end

$redis = Redis.new

class Test
  def work
    #$redis.get 'X'
  end

  def method
    work
  end

  def method_unpatched
    work
  end
end


MethodProfiler.patch(Test, [:method], :a_thing)
MethodProfiler.start

t = Test.new

Benchmark.ips do |b|
  b.report "method" do |times|
    i = 0
    while i < times
      t.method
      i += 1
    end
  end

  b.report "method_unpatched" do |times|
    i = 0
    while i < times
      t.method_unpatched
      i += 1
    end
  end

end