Fix helper methods and document metric builder options

lib/gitlab/metrics/concern.rb

@@ -65,28 +65,28 @@ module Gitlab
         # @param [Symbol] name
         # @param [Hash] opts
         def fetch_counter(name, opts = {}, &block)
-          define_metric(:counter, name, opts, &block)
+          fetch_metric(:counter, name, opts, &block)
         end
 
         # DFetch and/or initialize gauge metric
         # @param [Symbol] name
         # @param [Hash] opts
         def fetch_gauge(name, opts = {}, &block)
-          define_metric(:counter, name, opts, &block)
+          fetch_metric(:counter, name, opts, &block)
         end
 
         # Fetch and/or initialize histogram metric
         # @param [Symbol] name
         # @param [Hash] opts
         def fetch_histogram(name, opts = {}, &block)
-          define_metric(:histogram, name, opts, &block)
+          fetch_metric(:histogram, name, opts, &block)
         end
 
         # Fetch and/or initialize summary metric
         # @param [Symbol] name
         # @param [Hash] opts
         def fetch_summary(name, opts = {}, &block)
-          define_metric(:summary, name, opts, &block)
+          fetch_metric(:summary, name, opts, &block)
         end
 
         # Define metric accessor method for a Counter

lib/gitlab/metrics/concern/metric_options.rb

@@ -10,30 +10,39 @@ module Gitlab
           @with_feature = options[:with_feature]
         end
 
+        # Documentation describing metric in metrics endpoint '/-/metrics'
         def docstring(docstring = nil)
           @docstring = docstring unless docstring.nil?
 
           @docstring
         end
 
+        # Gauge aggregation mode for multiprocess metrics
+        # - :all (default) returns each gauge for every process
+        # - :livesum all process'es gauges summed up
+        # - :max maximum value of per process gauges
+        # - :min minimum value of per process gauges
         def multiprocess_mode(mode = nil)
           @multiprocess_mode = mode unless mode.nil?
 
           @multiprocess_mode
         end
 
+        # Measurement buckets for histograms
         def buckets(buckets = nil)
           @buckets = buckets unless buckets.nil?
 
           @buckets
         end
 
+        # Base labels are merged with per metric labels
         def base_labels(base_labels = nil)
           @base_labels = base_labels unless base_labels.nil?
 
           @base_labels
         end
 
+        # Use feature toggle to control whether certain metric is enabled/disabled
         def with_feature(name = nil)
           @feature_name = name unless name.nil?