Move Prometheus presentation logic to PrometheusText

+ Use NullMetrics to mock metrics when unused
+ Use method_missing in NullMetrics mocking
+ Update prometheus gem to version that correctly uses transitive dependencies
+ Ensure correct folders are used in Multiprocess prometheus client tests.
+ rename Sessions controller's metric

1 files changed, 6 insertions, 16 deletions

diff --git a/lib/gitlab/metrics/dummy_metric.rb b/lib/gitlab/metrics/null_metric.rb
index d27bb83854a..1501cd38676 100644
--- a/lib/gitlab/metrics/dummy_metric.rb
+++ b/lib/gitlab/metrics/null_metric.rb
@@ -1,7 +1,12 @@
 module Gitlab
   module Metrics
     # Mocks ::Prometheus::Client::Metric and all derived metrics
-    class DummyMetric
+    class NullMetric
+      def method_missing(name, *args, &block)
+        nil
+      end
+
+      # these methods shouldn't be called when metrics are disabled
       def get(*args)
         raise NotImplementedError
       end
@@ -9,21 +14,6 @@ module Gitlab
       def values(*args)
         raise NotImplementedError
       end
-
-      # counter
-      def increment(*args)
-        # noop
-      end
-
-      # gauge
-      def set(*args)
-        # noop
-      end
-
-      # histogram / summary
-      def observe(*args)
-        # noop
-      end
     end
   end
 end