1 files changed, 80 insertions, 0 deletions
diff --git a/railties/lib/rails/rack/logger.rb b/railties/lib/rails/rack/logger.rb
new file mode 100644
index 0000000000..3a95b55811
--- /dev/null
+++ b/railties/lib/rails/rack/logger.rb
@@ -0,0 +1,80 @@
+# frozen_string_literal: true
+
+require "active_support/core_ext/time/conversions"
+require "active_support/core_ext/object/blank"
+require "active_support/log_subscriber"
+require "action_dispatch/http/request"
+require "rack/body_proxy"
+
+module Rails
+  module Rack
+    # Sets log tags, logs the request, calls the app, and flushes the logs.
+    #
+    # Log tags (+taggers+) can be an Array containing: methods that the +request+
+    # object responds to, objects that respond to +to_s+ or Proc objects that accept
+    # an instance of the +request+ object.
+    class Logger < ActiveSupport::LogSubscriber
+      def initialize(app, taggers = nil)
+        @app          = app
+        @taggers      = taggers || []
+      end
+
+      def call(env)
+        request = ActionDispatch::Request.new(env)
+
+        if logger.respond_to?(:tagged)
+          logger.tagged(compute_tags(request)) { call_app(request, env) }
+        else
+          call_app(request, env)
+        end
+      end
+
+      private
+
+        def call_app(request, env) # :doc:
+          instrumenter = ActiveSupport::Notifications.instrumenter
+          instrumenter.start "request.action_dispatch", request: request
+          logger.info { started_request_message(request) }
+          status, headers, body = @app.call(env)
+          body = ::Rack::BodyProxy.new(body) { finish(request) }
+          [status, headers, body]
+        rescue Exception
+          finish(request)
+          raise
+        ensure
+          ActiveSupport::LogSubscriber.flush_all!
+        end
+
+        # Started GET "/session/new" for 127.0.0.1 at 2012-09-26 14:51:42 -0700
+        def started_request_message(request) # :doc:
+          'Started %s "%s" for %s at %s' % [
+            request.request_method,
+            request.filtered_path,
+            request.remote_ip,
+            Time.now.to_default_s ]
+        end
+
+        def compute_tags(request) # :doc:
+          @taggers.collect do |tag|
+            case tag
+            when Proc
+              tag.call(request)
+            when Symbol
+              request.send(tag)
+            else
+              tag
+            end
+          end
+        end
+
+        def finish(request)
+          instrumenter = ActiveSupport::Notifications.instrumenter
+          instrumenter.finish "request.action_dispatch", request: request
+        end
+
+        def logger
+          Rails.logger
+        end
+    end
+  end
+end