Construct path_parameters from merged hash

This saves a hash allocation as well as the time to copy the
path_parameters from the temporary hash to the final hash.

Author: skipkayhil

actionpack/lib/action_dispatch/journey/router.rb

@@ -38,9 +38,7 @@ def serve(req)
             req.path_info = "/" + req.path_info unless req.path_info.start_with? "/"
           end
 
-          tmp_params = set_params.merge route.defaults, parameters
-
-          req.path_parameters = tmp_params
+          req.path_parameters = parameters
           req.route = route
 
           _, headers, _ = response = route.app.serve(req)
@@ -66,7 +64,6 @@ def recognize(rails_req)
             rails_req.path_info   = "/" + rails_req.path_info unless rails_req.path_info.start_with? "/"
           end
 
-          parameters = route.defaults.merge parameters
           yield(route, parameters)
         end
       end
@@ -124,7 +121,9 @@ def find_routes(req)
 
           routes.each do |r|
             match_data = r.path.match(path_info)
-            path_parameters = {}
+
+            path_parameters = req.path_parameters.merge r.defaults
+
             index = 1
             match_data.names.each do |name|
               if val = match_data[index]

actionpack/lib/action_dispatch/routing/route_set.rb

@@ -932,6 +932,7 @@ def recognize_path_with_request(req, path, extras, raise_on_missing: true)
               params[key] = URI::RFC2396_PARSER.unescape(value)
             end
           end
+          original_path_parameters = req.path_parameters
           req.path_parameters = params
           app = route.app
           if app.matches?(req) && app.dispatcher?
@@ -945,6 +946,8 @@ def recognize_path_with_request(req, path, extras, raise_on_missing: true)
           elsif app.matches?(req) && app.engine?
             path_parameters = app.rack_app.routes.recognize_path_with_request(req, path, extras, raise_on_missing: false)
             return path_parameters if path_parameters
+          else
+            req.path_parameters = original_path_parameters
           end
         end