Implement Resque integration configuration (#546)

* Changed: ConfigurationHelpers#remove_patch! to work with Integration patchers.

* Refactored: Resque to use Datadog::Contrib::Integration.

lib/ddtrace.rb

@@ -65,7 +65,7 @@ def configure(target = configuration, opts = {})
 require 'ddtrace/contrib/rails/integration'
 require 'ddtrace/contrib/rake/patcher'
 require 'ddtrace/contrib/redis/patcher'
-require 'ddtrace/contrib/resque/patcher'
+require 'ddtrace/contrib/resque/integration'
 require 'ddtrace/contrib/rest_client/integration'
 require 'ddtrace/contrib/sequel/integration'
 require 'ddtrace/contrib/sidekiq/integration'

lib/ddtrace/contrib/resque/configuration/settings.rb

@@ -0,0 +1,15 @@
+require 'ddtrace/contrib/configuration/settings'
+
+module Datadog
+  module Contrib
+    module Resque
+      module Configuration
+        # Custom settings for the Resque integration
+        class Settings < Contrib::Configuration::Settings
+          option :service_name, default: 'resque'
+          option :workers, default: []
+        end
+      end
+    end
+  end
+end

lib/ddtrace/contrib/resque/integration.rb

@@ -0,0 +1,39 @@
+require 'ddtrace/contrib/integration'
+require 'ddtrace/contrib/resque/configuration/settings'
+require 'ddtrace/contrib/resque/patcher'
+
+module Datadog
+  module Contrib
+    module Resque
+      # Description of Resque integration
+      class Integration
+        include Contrib::Integration
+
+        APP = 'resque'.freeze
+
+        register_as :resque, auto_patch: true
+
+        def self.version
+          Gem.loaded_specs['resque'] && Gem.loaded_specs['resque'].version
+        end
+
+        def self.present?
+          super && defined?(::Resque)
+        end
+
+        def default_configuration
+          Configuration::Settings.new
+        end
+
+        def patcher
+          Patcher
+        end
+
+        class << self
+          # Globally-acccesible reference for pre-forking optimization
+          attr_accessor :sync_writer
+        end
+      end
+    end
+  end
+end

lib/ddtrace/contrib/resque/patcher.rb

@@ -1,49 +1,39 @@
+require 'ddtrace/contrib/patcher'
+require 'ddtrace/ext/app_types'
+
 module Datadog
   module Contrib
-    # Namespace for `resque` integration
     module Resque
-      SERVICE = 'resque'.freeze
-
-      class << self
-        # Globally-acccesible reference for pre-forking optimization
-        attr_accessor :sync_writer
-      end
-
-      # Patcher for Resque integration - sets up the pin for the integration
+      # Patcher enables patching of 'resque' module.
       module Patcher
-        include Base
-        register_as :resque, auto_patch: true
-        option :service_name, default: SERVICE
-
-        @patched = false
-        option :workers, default: []
-
-        class << self
-          def patch
-            return @patched if patched? || !defined?(::Resque)
+        include Contrib::Patcher
 
-            require 'ddtrace/ext/app_types'
-            require_relative 'resque_job'
+        module_function
 
-            add_pin
-            get_option(:workers).each { |worker| worker.extend(ResqueJob) }
-            @patched = true
-          rescue => e
-            Tracer.log.error("Unable to apply Resque integration: #{e}")
-            @patched
-          end
+        def patched?
+          done?(:resque)
+        end
 
-          def patched?
-            @patched
+        def patch
+          do_once(:resque) do
+            begin
+              require_relative 'resque_job'
+              add_pin
+              get_option(:workers).each { |worker| worker.extend(ResqueJob) }
+            rescue StandardError => e
+              Datadog::Tracer.log.error("Unable to apply Resque integration: #{e}")
+            end
           end
+        end
 
-          private
+        def add_pin
+          Pin
+            .new(get_option(:service_name), app: Integration::APP, app_type: Ext::AppTypes::WORKER)
+            .onto(::Resque)
+        end
 
-          def add_pin
-            Pin
-              .new(get_option(:service_name), app: 'resque', app_type: Ext::AppTypes::WORKER)
-              .onto(::Resque)
-          end
+        def get_option(option)
+          Datadog.configuration[:resque].get_option(option)
         end
       end
     end

spec/support/configuration_helpers.rb

@@ -1,7 +1,15 @@
 module ConfigurationHelpers
   def remove_patch!(integration)
-    Datadog
-      .registry[integration]
-      .instance_variable_set('@patched', false)
+    if Datadog.registry[integration].respond_to?(:patcher)
+      Datadog.registry[integration].patcher.tap do |patcher|
+        if patcher.instance_variable_defined?(:@done_once)
+          patcher.instance_variable_get(:@done_once).delete(integration)
+        end
+      end
+    else
+      Datadog
+        .registry[integration]
+        .instance_variable_set('@patched', false)
+    end
   end
 end