Busted

Disclaimers

• Requires MRI Ruby 2.1.0dev at trunk

--

Find code that busts the Ruby 2.1+ cache.

• Report when code invalidates Ruby's internal cache
• Uses RubyVM.stat

Usage

Any Cache

Busted.cache? do
  class Beer
  end
end
#=> true

Busted.run do
  class Pizza
  end
end
#=> {:invalidations=>{:method=>0, :constant=>1}}

Busted.start
class Pie
end
Busted.finish
#=> {:invalidations=>{:method=>0, :constant=>1}}

Method Cache

Busted.method_cache? do
  def beer
  end
end
#=> true

Busted.method_cache_invalidations do
  def pizza
  end
end
#=> 1

Busted.run do
  def pie
  end
end
#=> {:invalidations=>{:method=>1, :constant=>0}}

Busted.start
def smoothie
end
Busted.finish
#=> {:invalidations=>{:method=>1, :constant=>0}}

Constant Cache

Busted.constant_cache? do
  STOUT = "stout"
end
#=> true

Busted.constant_cache_invalidations do
  CHEESE = "cheese"
end
#=> 1

Busted.run do
  PIE = "pumpkin"
end
#=> {:invalidations=>{:method=>0, :constant=>1}}

Busted.start
SMOOTHIE = "blueberry"
Busted.finish
#=> {:invalidations=>{:method=>0, :constant=>1}}

No Cache Busted

Busted.cache? do
  beer = "beer"
end
#=> false

Busted.run do
  pizza = "pizza"
end
#=> {:invalidations=>{:method=>0, :constant=>0}}

Busted.start
pie = "pie"
Busted.finish
#=> {:invalidations=>{:method=>0, :constant=>0}}

Advanced Usage

Busted can report method cache invalidation locations via dtrace. The running process must have root privileges, and dtrace must be installed.

trace.rb

require "busted"
require "pp"

report = Busted.run(trace: true) do
  def cookie
  end
end
pp report

$ whoami
simeon

$ id simeon
uid=501(simeon) gid=20(staff) groups=20(staff),80(admin)

# simeon is an admin; sudo does not require a password
$ sudo grep admin /etc/sudoers
%admin  ALL=(ALL) NOPASSWD: ALL

$ sudo dtrace -V
dtrace: Sun D 1.6.2

# No need to sudo
# Busted runs dtrace in a child process with root privileges
$ ruby trace.rb
{:invalidations=>{:method=>1, :constant=>0},
 :traces=>
  {:method=>[{:class=>"global", :sourcefile=>"trace.rb", :lineno=>"5"}]}}

start_finish_trace.rb

require "busted"
require "pp"

Busted.start trace: true
def ice_cream
end
pp Busted.finish

$ ruby start_finish_trace.rb
{:invalidations=>{:method=>1, :constant=>0},
 :traces=>
  {:method=>
    [{:class=>"global", :sourcefile=>"start_finish_trace.rb", :lineno=>"5"}]}}

Busted includes an example dtrace probe for use on the command line or an application. See the probe for usage.

Installation

Requires MRI Ruby 2.1.0dev

Add this line to your application's Gemfile:

gem "busted"

And then execute:

$ bundle

Or install it yourself as:

$ gem install busted

Contributing

Check out this guide if you'd like to contribute.

License

This project is licensed under the MIT License.

Standing On The Shoulders Of Giants

A big thank you to Charlie Somerville and Aman Gupta for helping flesh out RubyVM.stat and committing it to Ruby core!