initial draft of capistrano benchmarker

gistfile1.rb

require 'benchmark'

module Capistrano::Benchmark
  def self.included(base)
    base.class_eval do
      alias execute_task_without_benchmark execute_task
      alias execute_task execute_task_with_benchmark
    end
  end

  def self.print
    Report.print Node::TOPLEVEL
  end

  def execute_task_with_benchmark(task)
    Trace.node task.fully_qualified_name do
      execute_task_without_benchmark task
    end
  end

  class Node
    attr_reader :name, :children, :total

    def initialize(name)
      @name = name
      @children = []
      @total = 0
    end

    def benchmark
      @total = Benchmark.realtime { @result = yield }
      @result
    end

    def time
      total - nested
    end

    def nested
      children.map(&:total).inject(:+).to_f
    end

    def create_child(name)
      self.class.new(name).tap {|it| @children << it }
    end
  end

  Node::TOPLEVEL = Node.new 'toplevel'

  module Trace
    extend self
    @trace = [Node::TOPLEVEL]

    def node(name, &block)
      new_node = current_node.create_child name
      with(new_node) { current_node.benchmark &block }
    end

    private

    def current_node
      @trace.last
    end

    def with(task)
      @trace.push task
      yield
    ensure
      @trace.pop
    end
  end

  module Report
    extend self
    NUMBERS_MARGIN = 45

    def print(node, level=0)
      print_stats node, level unless level == 0
      node.children.each {|it| print it, level+1 }
    end

    private

    def print_stats(node, level)
      puts intro(node,level) + fill_margin(node,level) + time(node)
    end

    def fill_margin(node, level)
      '-' * margin_size(node, level)
    end

    def margin_size(node, level)
      NUMBERS_MARGIN - intro(node, level).size
    end

    def intro(node, level)
      "#{ident level}. #{node.name}"
    end

    def ident(level)
      '  ' * level + level.to_s
    end

    def time(node)
      "-- #{format_time node.total} -- " +
      "-- #{format_time node.nested} -- " +
      "-- #{format_time node.time}"
    end

    def format_time(time)
      '%5.1fs' % time
    end
  end
end

Capistrano::Configuration.send :include, Capistrano::Benchmark
at_exit { Capistrano::Benchmark.print }