Merge 6bc415d into 733408e

lib/prometheus/client/formats/json.rb

@@ -24,10 +24,6 @@ def self.marshal(registry)
             }
           end.to_json
         end
-
-        def self.unmarshal(*)
-          fail NotImplementedError
-        end
       end
     end
   end

lib/prometheus/client/formats/text.rb

@@ -0,0 +1,57 @@
+# encoding: UTF-8
+
+module Prometheus
+  module Client
+    module Formats
+      # Text format is human readable mainly used for manual inspection.
+      module Text
+        VERSION = '0.0.4'
+        TYPE    = 'text/plain; version=' + VERSION
+
+        METRIC_LINE = '%s%s %s'
+        TYPE_LINE   = '# TYPE %s %s'
+        HELP_LINE   = '# HELP %s %s'
+
+        LABEL     = '%s="%s"'
+        SEPARATOR = ','
+        DELIMITER = "\n"
+
+        REGEX   = { doc: /[\n\\]/, label: /[\n\\"]/ }
+        REPLACE = { "\n" => '\n', '\\' => '\\\\', '"' => '\"' }
+
+        def self.marshal(registry)
+          lines = []
+
+          registry.metrics.each do |metric|
+            lines << format(TYPE_LINE, metric.name, metric.type)
+            lines << format(HELP_LINE, metric.name, escape(metric.docstring))
+
+            metric.values.each do |label_set, value|
+              set = metric.base_labels.merge(label_set)
+              lines << format(METRIC_LINE, metric.name, labels(set), value)
+            end
+          end
+
+          # there must be a trailing delimiter
+          (lines << nil).join(DELIMITER)
+        end
+
+        private
+
+        def self.labels(set)
+          return if set.empty?
+
+          strings = set.reduce([]) do |memo, (key, value)|
+            memo << format(LABEL, key, escape(value, :label))
+          end
+
+          "{#{strings.join(SEPARATOR)}}"
+        end
+
+        def self.escape(string, format = :doc)
+          string.to_s.gsub(REGEX[format], REPLACE)
+        end
+      end
+    end
+  end
+end

spec/prometheus/client/formats/text_spec.rb

@@ -0,0 +1,47 @@
+# encoding: UTF-8
+
+require 'prometheus/client/formats/text'
+
+describe Prometheus::Client::Formats::Text do
+  let(:registry) do
+    double(metrics: [
+      double(
+        name: :foo,
+        docstring: 'foo description',
+        base_labels: {},
+        type: :counter,
+        values: { { code: 'red' } => 42 },
+      ),
+      double(
+        name: :bar,
+        docstring: "bar description\nwith newline",
+        base_labels: { status: 'success' },
+        type: :gauge,
+        values: { { code: 'pink' } => 15 },
+      ),
+      double(
+        name: :baz,
+        docstring: 'baz "description" \\escaping',
+        base_labels: {},
+        type: :counter,
+        values: { { text: %Q(with "quotes", \\escape \n and newline) } => 15 },
+      ),
+    ],)
+  end
+
+  describe '.marshal' do
+    it 'returns a Text format version 0.0.4 compatible representation' do
+      expect(subject.marshal(registry)).to eql <<-'TEXT'
+# TYPE foo counter
+# HELP foo foo description
+foo{code="red"} 42
+# TYPE bar gauge
+# HELP bar bar description\nwith newline
+bar{status="success",code="pink"} 15
+# TYPE baz counter
+# HELP baz baz "description" \\escaping
+baz{text="with \"quotes\", \\escape \n and newline"} 15
+      TEXT
+    end
+  end
+end