cleanup initialization process to better support Rails 3

lib/rpm_contrib.rb

@@ -1,34 +1,43 @@
-
 RPM_CONTRIB_LIB = File.dirname(__FILE__)
 
 module RPMContrib
   VERSION = File.read(RPM_CONTRIB_LIB+"/../CHANGELOG")[/Version ([\d\.]+)$/, 1]
-end
 
-# Perform any framework/dispatcher detection before loading the rpm
-# gem.
+  def self.init_sequence
+    Proc.new do
+      # Tell the agent to load all the files in the
+      # rpm_contrib/instrumentation directory.
+      NewRelic::Agent.add_instrumentation(RPM_CONTRIB_LIB+"/rpm_contrib/instrumentation/**/*.rb")
+
+      # Load all the Sampler class definitions.  These will register
+      # automatically with the agent.
+      Dir.glob(RPM_CONTRIB_LIB + "/rpm_contrib/samplers/**/*.rb") { |file| require file }
+    end
+  end
 
+end
+
+# Perform any framework/dispatcher detection before loading the rpm gem.
 raise "The rpm_contrib gem must be loaded before the newrelic_rpm gem." if defined?(::NewRelic)
 
 Dir.glob(RPM_CONTRIB_LIB + "/rpm_contrib/detection/**/*.rb") { |file| require file }
 
 require 'newrelic_rpm'
 
-init_sequence = Proc.new do
-
-  # Tell the agent to load all the files in the
-  # rpm_contrib/instrumentation directory.
-  NewRelic::Agent.add_instrumentation(RPM_CONTRIB_LIB+"/rpm_contrib/instrumentation/**/*.rb")
-
-  # Load all the Sampler class definitions.  These will register
-  # automatically with the agent.
-  Dir.glob(RPM_CONTRIB_LIB + "/rpm_contrib/samplers/**/*.rb") { |file| require file }
-end
-
-if defined?(Rails.configuration)
-  Rails.configuration.after_initialize &init_sequence
+if defined? Rails
+  # Rails 3.x+
+  if Rails.respond_to?(:version) && Rails.version =~ /^3/
+    module NewRelic
+      class Railtie < Rails::Railtie
+        initializer("rpm_contrib.start_plugin", &RPMContrib.init_sequence)
+      end
+    end
+  # Rails 2.x
+  elsif defined?(Rails) && Rails.respond_to?(:configuration)
+    Rails.configuration.after_initialize &RPMContrib.init_sequence
+  else
+    raise "The rpm_contrib gem supports Rails 2.2+ only."
+  end
 else
-  init_sequence.call
-end
-
-
+  RPMContrib.init_sequence.call
+end