1 files changed, 31 insertions, 0 deletions
diff --git a/lib/gitlab/graphql/tracers/timer_tracer.rb b/lib/gitlab/graphql/tracers/timer_tracer.rb
new file mode 100644
index 00000000000..326620a22bc
--- /dev/null
+++ b/lib/gitlab/graphql/tracers/timer_tracer.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Graphql
+    module Tracers
+      # This graphql-ruby tracer records duration for trace events and merges
+      # the duration into the trace event's metadata. This way, separate tracers
+      # can all use the same duration information.
+      #
+      # NOTE: TimerTracer should be applied last **after** other tracers, so
+      # that it runs first (similar to function composition)
+      class TimerTracer
+        def self.use(schema)
+          schema.tracer(self.new)
+        end
+
+        def trace(key, data)
+          start_time = Gitlab::Metrics::System.monotonic_time
+
+          result = yield
+
+          duration_s = Gitlab::Metrics::System.monotonic_time - start_time
+
+          data[:duration_s] = duration_s
+
+          result
+        end
+      end
+    end
+  end
+end