Add request env to tracing ActionDispatch contrib

ruby 3.3.5 (2024-09-03 revision ef084cc8f4) [arm64-darwin23]
Warming up --------------------------------------
             w: gsub    72.280k i/100ms
              w: sub    81.689k i/100ms
    w: delete_suffix   502.700k i/100ms
           w/o: gsub   116.580k i/100ms
            w/o: sub   195.557k i/100ms
  w/o: delete_suffix   225.558k i/100ms
Calculating -------------------------------------
             w: gsub      1.609M (±68.8%) i/s  (621.46 ns/i) -     10.914M in  30.723566s
              w: sub      3.185M (±65.6%) i/s  (313.95 ns/i) -     17.481M in  30.198337s
    w: delete_suffix      4.903M (±118.8%) i/s  (203.97 ns/i) -     45.746M in  31.428342s
           w/o: gsub      4.935M (±64.8%) i/s  (202.61 ns/i) -     46.632M in  30.271821s
            w/o: sub      4.876M (±63.5%) i/s  (205.09 ns/i) -     46.934M in  30.233153s
  w/o: delete_suffix     10.564M (±78.8%) i/s   (94.66 ns/i) -     48.495M in  30.639072s

Author: Strech

lib/datadog/tracing/contrib/action_pack/action_dispatch/instrumentation.rb

@@ -9,20 +9,24 @@ module ActionPack
         module ActionDispatch
           # Instrumentation for ActionDispatch components
           module Instrumentation
+            HTTP_ROUTE_KEY = 'datadog.http.route'
+            SCRIPT_NAME_KEY = 'SCRIPT_NAME'
+            FORMAT_SUFFIX = '(.:format)'
+
             module_function
 
-            def set_http_route_tags(route_spec, script_name)
+            def set_http_route_tags(route_spec, route_path)
               return unless Tracing.enabled?
 
               return unless route_spec
 
               request_trace = Tracing.active_trace
               return unless request_trace
 
-              request_trace.set_tag(Tracing::Metadata::Ext::HTTP::TAG_ROUTE, route_spec.to_s.gsub(/\(.:format\)\z/, ''))
+              request_trace.set_tag(Tracing::Metadata::Ext::HTTP::TAG_ROUTE, route_spec)
 
-              if script_name && !script_name.empty?
-                request_trace.set_tag(Tracing::Metadata::Ext::HTTP::TAG_ROUTE_PATH, script_name)
+              if route_path && !route_path.empty?
+                request_trace.set_tag(Tracing::Metadata::Ext::HTTP::TAG_ROUTE_PATH, route_path)
               end
             end
 
@@ -40,16 +44,18 @@ module Journey
               # Instrumentation for ActionDispatch::Journey::Router for Rails versions older than 7.1
               module Router
                 def find_routes(req)
+                  # result is an array of [match, parameters, route] tuples
                   result = super
+                  result.each do |_, _, route|
+                    next unless Instrumentation.dispatcher_route?(route)
 
-                  # result is an array of [match, parameters, route] tuples
-                  routes = result.map(&:last)
+                    http_route = route.path.spec.to_s
+                    http_route.delete_suffix!(FORMAT_SUFFIX)
 
-                  routes.each do |route|
-                    if Instrumentation.dispatcher_route?(route)
-                      Instrumentation.set_http_route_tags(route.path.spec, req.env['SCRIPT_NAME'])
-                      break
-                    end
+                    req.env[HTTP_ROUTE_KEY] = http_route
+                    Instrumentation.set_http_route_tags(http_route, req.env[SCRIPT_NAME_KEY])
+
+                    break
                   end
 
                   result
@@ -62,7 +68,11 @@ module LazyRouter
                 def find_routes(req)
                   super do |match, parameters, route|
                     if Instrumentation.dispatcher_route?(route)
-                      Instrumentation.set_http_route_tags(route.path.spec, req.env['SCRIPT_NAME'])
+                      http_route = route.path.spec.to_s
+                      http_route.delete_suffix!(FORMAT_SUFFIX)
+
+                      req.env[HTTP_ROUTE_KEY] = http_route
+                      Instrumentation.set_http_route_tags(http_route, req.env[SCRIPT_NAME_KEY])
                     end
 
                     yield [match, parameters, route]