statsd_middleware.rb in salestation-3.5.0

- old
+ new

@@ -1,19 +1,22 @@
 # frozen_string_literal: true
 
 module Salestation
   class Web < Module
     class StatsdMiddleware
+      EXTRA_TAGS_ENV_KEY = 'salestation.statsd.tags'
 
+      DURATION_PRECISION = 6
+
       def initialize(app, statsd, metric:)
         @app = app
         @statsd = statsd
         @metric = metric
       end
 
       def call(env)
-        start = Time.now
+        start = system_monotonic_time
 
         status, header, body = @app.call env
 
         method = env['REQUEST_METHOD']
         path =
@@ -21,16 +24,28 @@
             route.split(' ').last
           else
             'unknown-route'
           end
 
-        @statsd.timing(@metric, (Time.now - start) * 1000, tags: [
+        tags = [
           "path:#{ path }",
           "method:#{ method }",
           "status:#{ status }"
-        ])
+        ] + env.fetch(EXTRA_TAGS_ENV_KEY, [])
 
+        @statsd.timing(@metric, duration(from: start), tags: tags)
+
         [status, header, body]
+      end
+
+      private
+
+      def duration(from:)
+        (system_monotonic_time - from).round(DURATION_PRECISION)
+      end
+
+      def system_monotonic_time
+        Process.clock_gettime(Process::CLOCK_MONOTONIC)
       end
     end
   end
 end