Benchmark of using different methods to convert complex Mash to Hash

1_notes.md

Using the following Gem versions:

• benchmark-ips (2.1.0)
• chef (11.16.4), which includes:
  • erubis (2.7.0)
  • json (1.8.1)

Ruby 1.9.3:

Calculating -------------------------------------
         monkeypatch    75.000  i/100ms
      mash2json2yaml    73.000  i/100ms
-------------------------------------------------
         monkeypatch    745.984  (± 9.9%) i/s -      3.750k
      mash2json2yaml    761.028  (± 7.9%) i/s -      3.796k

Comparison:
      mash2json2yaml:      761.0 i/s
         monkeypatch:      746.0 i/s - 1.02x slower

Ruby 2.1.5:

Calculating -------------------------------------
         monkeypatch    88.000  i/100ms
      mash2json2yaml    86.000  i/100ms
-------------------------------------------------
         monkeypatch    884.203  (± 4.0%) i/s -      4.488k
      mash2json2yaml    865.697  (± 3.8%) i/s -      4.386k

Comparison:
         monkeypatch:      884.2 i/s
      mash2json2yaml:      865.7 i/s - 1.02x slower

2_benchmark.rb

require 'benchmark/ips'

require 'chef'
require 'erubis'

HASHDATA = {
  'conf' => [
    {
      'exclude' => [
        {
          'domain' => 'evil_domain'
        }
      ],
      'include' => {
        'attribute' => {
          'bytesReceived' => { 'metric_type' => 'counter', 'alias' => 'tomcat.bytes_rcvd' },
          'maxThreads' => { 'metric_type' => 'gauge', 'alias' => 'tomcat.threads.max' }
        },
        'bean' => 'tomcat_bean',
        'domain' => 'domain0',
        'type' => 'ThreadPool'
      },
      'include' => {
        'attributes' => [
          'BloomFilterDiskSpaceUsed',
          'Capacity'
        ],
        'bean_name' => 'com.datadoghq.test:type=BeanType,tag1=my_bean_name',
        'domain' => 'org.apache.cassandra.db',
        'foo' => 'bar'
      }
    }
  ],
  'extra_key' => 'extra_val',
  'host' => 'localhost',
  'port' => 9999
}

# Simulate Attribute loading by creating the Mash directly
MASH1 = Chef::Node::ImmutableMash.new(HASHDATA)
MASH2 = Chef::Node::ImmutableMash.new(HASHDATA)

@mash_array = Chef::Node::ImmutableArray.new [MASH1, MASH2]

# Monkeypatching of Chef classes to provide `deep` class conversion
class Chef
  class Node
    class ImmutableMash
      def deep_to_hash
        h = {}
        self.each do |k,v|
          if v.respond_to?('deep_to_hash')
            h[k] = v.deep_to_hash
          elsif v.respond_to?('deep_to_a')
            h[k] = v.deep_to_a
          else
            h[k] = v
          end
        end
        return h
      end
    end

    class ImmutableArray
      def deep_to_a
        a = []
        self.each do |v|
          if v.respond_to?('deep_to_hash')
            a << v.deep_to_hash
          elsif v.respond_to?('deep_to_a')
            a << v.deep_to_a
          else
            a << v
          end
        end
        return a
      end
    end
  end
end

# Common render method for benchmarks
def render(template)
  eruby = Erubis::Eruby.new(template)
  output = eruby.evaluate(Erubis::Context)
end

def monkeypatch
  render("<%= YAML.dump({ 'instances' => #{@mash_array.deep_to_a} }) %>")
end

def mash2json2yaml
  render("<%= JSON.parse(({ 'instances' => #{@mash_array}.to_a }).to_json).to_yaml %>")
end

Benchmark.ips do |x|
  x.report('monkeypatch')    { monkeypatch }
  x.report('mash2json2yaml') { mash2json2yaml }
  x.compare!
end