WIP exchangeable value types

example.rb

@@ -0,0 +1,30 @@
+$LOAD_PATH.unshift("./lib")
+
+require 'prometheus/client'
+require 'prometheus/client/formats/text.rb'
+
+prometheus = Prometheus::Client.registry
+
+counter = Prometheus::Client::Counter.new(:counter, 'Example counter')
+gauge = Prometheus::Client::Gauge.new(:gauge, 'Example gauge')
+histogram = Prometheus::Client::Histogram.new(:histogram, 'Example histogram', {}, [0, 1, 2])
+summary = Prometheus::Client::Histogram.new(:summary, 'Example summary', {})
+prometheus.register(counter)
+prometheus.register(gauge)
+prometheus.register(histogram)
+prometheus.register(summary)
+
+counter.increment({'foo': 'bar'}, 2)
+counter.increment({'foo': 'biz'}, 4)
+gauge.set({'foo': 'bar'}, 3)
+gauge.set({'foo': 'biz'}, 3)
+histogram.observe({'foo': 'bar'}, 0.5)
+histogram.observe({'foo': 'biz'}, 0.5)
+histogram.observe({'foo': 'bar'}, 1.5)
+histogram.observe({'foo': 'biz'}, 2)
+summary.observe({'foo': 'bar'}, 0.5)
+summary.observe({'foo': 'biz'}, 0.5)
+summary.observe({'foo': 'bar'}, 1.5)
+summary.observe({'foo': 'biz'}, 2)
+
+puts Prometheus::Client::Formats::Text.marshal(prometheus)

lib/prometheus/client/counter.rb

@@ -1,6 +1,7 @@
 # encoding: UTF-8
 
 require 'prometheus/client/metric'
+require 'prometheus/client/valuetype'
 
 module Prometheus
   module Client
@@ -14,13 +15,13 @@ def increment(labels = {}, by = 1)
         raise ArgumentError, 'increment must be a non-negative number' if by < 0
 
         label_set = label_set_for(labels)
-        synchronize { @values[label_set] += by }
+        synchronize { @values[label_set].increment(by) }
       end
 
       private
 
-      def default
-        0
+      def default(labels)
+        Prometheus::Client::ValueType.new(type, @name, @name, labels)
       end
     end
   end

lib/prometheus/client/formats/text.rb

@@ -47,29 +47,29 @@ def representation(metric, label_set, value, &block)
             elsif metric.type == :histogram
               histogram(metric.name, set, value, &block)
             else
-              yield metric(metric.name, labels(set), value)
+              yield metric(metric.name, labels(set), value.get)
             end
           end
 
           def summary(name, set, value)
             value.each do |q, v|
-              yield metric(name, labels(set.merge(quantile: q)), v)
+              yield metric(name, labels(set.merge(quantile: q)), v.get)
             end
 
             l = labels(set)
-            yield metric("#{name}_sum", l, value.sum)
-            yield metric("#{name}_count", l, value.total)
+            yield metric("#{name}_sum", l, value.sum.get)
+            yield metric("#{name}_count", l, value.total.get)
           end
 
           def histogram(name, set, value)
             value.each do |q, v|
-              yield metric(name, labels(set.merge(le: q)), v)
+              yield metric(name, labels(set.merge(le: q)), v.get)
             end
-            yield metric(name, labels(set.merge(le: '+Inf')), value.total)
+            yield metric(name, labels(set.merge(le: '+Inf')), value.total.get)
 
             l = labels(set)
-            yield metric("#{name}_sum", l, value.sum)
-            yield metric("#{name}_count", l, value.total)
+            yield metric("#{name}_sum", l, value.sum.get)
+            yield metric("#{name}_count", l, value.total.get)
           end
 
           def metric(name, labels, value)

lib/prometheus/client/gauge.rb

@@ -13,7 +13,7 @@ def type
 
       # Sets the value for the given label set
       def set(labels, value)
-        @values[label_set_for(labels)] = value
+        @values[label_set_for(labels)].set(value)
       end
     end
   end

lib/prometheus/client/histogram.rb

@@ -12,21 +12,22 @@ class Histogram < Metric
       class Value < Hash
         attr_accessor :sum, :total
 
-        def initialize(buckets)
-          @sum = 0.0
-          @total = 0
+        def initialize(type, name, labels, buckets)
+          @sum = ValueType.new(type, name, name.to_s + '_sum', labels)
+          # TODO: get rid of total and use +Inf bucket instead.
+          @total = ValueType.new(type, name, name.to_s + '_count', labels)
 
           buckets.each do |bucket|
-            self[bucket] = 0
+            self[bucket] = ValueType.new(type, name, name.to_s + '_count', labels)
           end
         end
 
         def observe(value)
-          @sum += value
-          @total += 1
+          @sum.increment(value)
+          @total.increment()
 
           each_key do |bucket|
-            self[bucket] += 1 if value <= bucket
+            self[bucket].increment() if value <= bucket
           end
         end
       end
@@ -61,8 +62,9 @@ def observe(labels, value)
 
       private
 
-      def default
-        Value.new(@buckets)
+      def default(labels)
+        # TODO: default function needs to know key of hash info (label names and values)
+        Value.new(type, @name, labels, @buckets)
       end
 
       def sorted?(bucket)

lib/prometheus/client/metric.rb

@@ -12,7 +12,7 @@ class Metric
       def initialize(name, docstring, base_labels = {})
         @mutex = Mutex.new
         @validator = LabelSetValidator.new
-        @values = Hash.new { |hash, key| hash[key] = default }
+        @values = Hash.new { |hash, key| hash[key] = default(key) }
 
         validate_name(name)
         validate_docstring(docstring)
@@ -27,7 +27,7 @@ def initialize(name, docstring, base_labels = {})
       def get(labels = {})
         @validator.valid?(labels)
 
-        @values[labels]
+        @values[labels].get
       end
 
       # Returns all label sets with their values
@@ -41,8 +41,8 @@ def values
 
       private
 
-      def default
-        nil
+      def default(labels)
+        ValueType.new(@name, @name, labels, nil)
       end
 
       def validate_name(name)

lib/prometheus/client/summary.rb

@@ -14,12 +14,12 @@ class Summary < Metric
       class Value < Hash
         attr_accessor :sum, :total
 
-        def initialize(estimator)
-          @sum = estimator.sum
-          @total = estimator.observations
+        def initialize(name, labels, estimator)
+          @sum = ValueType.new(name, name + '_sum', labels, estimator.sum)
+          @total = ValueType.new(name, name + '_count', labels, estimator.observations)
 
           estimator.invariants.each do |invariant|
-            self[invariant.quantile] = estimator.query(invariant.quantile)
+            self[invariant.quantile] = ValueType.new(name, labels, estimator.query(invariant.quantile), nil)
           end
         end
       end

lib/prometheus/client/valuetype.rb

@@ -0,0 +1,25 @@
+# encoding: UTF-8
+
+module Prometheus
+  module Client
+    class SimpleValue
+      def initialize(type, metric_name, name, labels, value = 0)
+        @value = value
+      end
+
+      def set(value)
+        @value = value
+      end
+
+      def increment(by = 1)
+        @value += by
+      end
+
+      def get()
+        @value
+      end
+    end
+
+    ValueType = SimpleValue
+  end
+end