Add ActionDispatch::Notifications middleware.

1 files changed, 24 insertions, 0 deletions

diff --git a/actionpack/lib/action_dispatch/middleware/notifications.rb b/actionpack/lib/action_dispatch/middleware/notifications.rb
new file mode 100644
index 0000000000..01d2cbb435
--- /dev/null
+++ b/actionpack/lib/action_dispatch/middleware/notifications.rb
@@ -0,0 +1,24 @@
+module ActionDispatch
+  # Provide notifications in the middleware stack. Notice that for the before_dispatch
+  # and after_dispatch notifications, we just send the original env, so we don't pile
+  # up large env hashes in the queue. However, in exception cases, the whole env hash
+  # is actually useful, so we send it all.
+  class Notifications
+    def initialize(app)
+      @app = app
+    end
+
+    def call(stack_env)
+      env = stack_env.dup
+      ActiveSupport::Notifications.instrument("action_dispatch.before_dispatch", :env => env)
+
+      ActiveSupport::Notifications.instrument!("action_dispatch.after_dispatch", :env => env) do
+        @app.call(stack_env)
+      end
+    rescue Exception => exception
+      ActiveSupport::Notifications.instrument('action_dispatch.exception',
+        :env => stack_env, :exception => exception)
+      raise exception
+    end
+  end
+end
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