Merge pull request #228 from lostisland/instrumentation

add instrumentation middleware.

lib/faraday/request.rb

@@ -18,7 +18,8 @@ class Request < Struct.new(:method, :path, :params, :headers, :body, :options)
       :retry => [:Retry, 'retry'],
       :authorization => [:Authorization, 'authorization'],
       :basic_auth => [:BasicAuthentication, 'basic_authentication'],
-      :token_auth => [:TokenAuthentication, 'token_authentication']
+      :token_auth => [:TokenAuthentication, 'token_authentication'],
+      :instrumentation => [:Instrumentation, 'instrumentation']
 
     def self.create(request_method)
       new(request_method).tap do |request|

lib/faraday/request/instrumentation.rb

@@ -0,0 +1,38 @@
+module Faraday
+  class Request::Instrumentation < Faraday::Middleware
+    class Options < Faraday::Options.new(:name, :instrumenter)
+      def name
+        self[:name] ||= 'request.faraday'
+      end
+
+      def instrumenter
+        self[:instrumenter] ||= ActiveSupport::Notifications
+      end
+    end
+
+    # Public: Instruments requests using Active Support.
+    #
+    # Measures time spent only for synchronous requests.
+    #
+    # Examples
+    #
+    #   ActiveSupport::Notifications.subscribe('request.faraday') do |name, starts, ends, _, env|
+    #     url = env[:url]
+    #     http_method = env[:method].to_s.upcase
+    #     duration = ends - starts
+    #     $stderr.puts '[%s] %s %s (%.3f s)' % [url.host, http_method, url.request_uri, duration]
+    #   end
+    def initialize(app, options = nil)
+      super(app)
+      @name, @instrumenter = Options.from(options).values
+    end
+
+    def call(env)
+      @instrumenter.instrument(@name, env) do
+        @app.call(env)
+      end
+    end
+  end
+end
+
+

test/middleware/instrumentation_test.rb

@@ -0,0 +1,75 @@
+require File.expand_path("../../helper", __FILE__)
+
+module Middleware
+  class InstrumentationTest < Faraday::TestCase
+    def setup
+      @instrumenter = FakeInstrumenter.new
+    end
+
+    def test_default_name
+      assert_equal 'request.faraday', options.name
+    end
+
+    def test_default_instrumenter
+      begin
+        instrumenter = options.instrumenter
+      rescue NameError => err
+        assert_equal :ActiveSupport, err.name
+      else
+        assert_equal ActiveSupport::Notifications, instrumenter
+      end
+    end
+
+    def test_name
+      assert_equal 'booya', options(:name => 'booya').name
+    end
+
+    def test_instrumenter
+      assert_equal :boom, options(:instrumenter => :boom).instrumenter
+    end
+
+    def test_instrumentation
+      assert_equal 0, @instrumenter.instrumentations.size
+
+      faraday = conn :name => 'booya'
+      res = faraday.get '/'
+      assert_equal 'ok', res.body
+
+      assert_equal 1, @instrumenter.instrumentations.size
+      name, env = @instrumenter.instrumentations.first
+      assert_equal 'booya', name
+      assert_equal '/', env[:url].path
+    end
+
+    class FakeInstrumenter
+      attr_reader :instrumentations
+
+      def initialize
+        @instrumentations = []
+      end
+
+      def instrument(name, env)
+        @instrumentations << [name, env]
+        yield
+      end
+    end
+
+    def options(hash = nil)
+      Faraday::Request::Instrumentation::Options.from hash
+    end
+
+    def conn(hash = nil)
+      hash ||= {}
+      hash[:instrumenter] = @instrumenter
+
+      Faraday.new do |f|
+        f.request :instrumentation, hash
+        f.adapter :test do |stub|
+          stub.get '/' do
+            [200, {}, 'ok']
+          end
+        end
+      end
+    end
+  end
+end