Refactored: Runtime::Metrics into Metrics class.

docs/GettingStarted.md

@@ -1757,20 +1757,17 @@ If metrics are configured, the trace library will automatically collect and send
 
 These include:
 
-| Name                                  | Type    | Description                        |
-| ------------------------------------- | ------- | ---------------------------------- |
-| `datadog.tracer.runtime.class_count`  | `gauge` | Number of classes in memory space. |
-| `datadog.tracer.runtime.heap_size`.   | `gauge` | Size of memory heap, in bytes.     |
-| `datadog.tracer.runtime.thread_count` | `gauge` | Number of threads.                 |
+| Name                        | Type    | Description                                              |
+| --------------------------  | ------- | -------------------------------------------------------- |
+| `runtime.ruby.class_count`  | `gauge` | Number of classes in memory space.                       |
+| `runtime.ruby.thread_count` | `gauge` | Number of threads.                                       |
+| `runtime.ruby.gc.*`.        | `gauge` | Garbage collection statistics (one per value in GC.stat) |
 
 In addition, all metrics will include the following tags:
 
-| Name                              | Description                                                         |
-| --------------------------------- | ------------------------------------------------------------------- |
-| `datadog.tracer.lang`             | Programming language traced. (e.g. `ruby`)                          |
-| `datadog.tracer.lang_interpreter` | Language interpreter used, if available. (e.g. `ruby-x86_64-linux`) |
-| `datadog.tracer.lang_version`     | Version of language traced. (e.g. `2.3.7`)                          |
-| `datadog.tracer.version`          | Version of tracer library/module. (e.g. `0.16.1` )                  |
+| Name       | Description                                |
+| ---------- | ------------------------------------------ |
+| `language` | Programming language traced. (e.g. `ruby`) |
 
 ### OpenTracing
 

lib/ddtrace/configuration.rb

@@ -23,6 +23,10 @@ def metrics
       configuration.metrics
     end
 
+    def runtime_metrics
+      configuration.runtime_metrics
+    end
+
     def tracer
       configuration.tracer
     end

lib/ddtrace/configuration/settings.rb

@@ -17,6 +17,7 @@ class Settings
               lazy: true
 
       option :metrics, default: Metrics.new
+      option :runtime_metrics, default: Runtime::Metrics.new
       option :tracer, default: Tracer.new
 
       def initialize(options = {})
@@ -32,14 +33,24 @@ def configure(options = {})
         yield(self) if block_given?
       end
 
+      remove_method :metrics
       def metrics(options = nil)
         metrics = get_option(:metrics)
         return metrics if options.nil?
 
         metrics.configure(options)
       end
 
+      remove_method :runtime_metrics
+      def runtime_metrics(options = nil)
+        runtime_metrics = get_option(:runtime_metrics)
+        return runtime_metrics if options.nil?
+
+        runtime_metrics.configure(options)
+      end
+
       # Backwards compatibility for configuring tracer e.g. `c.tracer debug: true`
+      remove_method :tracer
       def tracer(options = nil)
         tracer = options && options.key?(:instance) ? set_option(:tracer, options[:instance]) : get_option(:tracer)
 

lib/ddtrace/ext/runtime.rb

@@ -15,10 +15,17 @@ module Runtime
       LANG_VERSION = RUBY_VERSION
       TRACER_VERSION = Datadog::VERSION::STRING
 
+      TAG_LANG = 'language'.freeze
+      TAG_RUNTIME_ID = 'runtime-id'.freeze
+
       # Metrics
-      METRIC_CLASS_COUNT = 'datadog.tracer.runtime.class_count'.freeze
-      METRIC_HEAP_SIZE = 'datadog.tracer.runtime.heap_size'.freeze
-      METRIC_THREAD_COUNT = 'datadog.tracer.runtime.thread_count'.freeze
+      module Metrics
+        METRIC_CLASS_COUNT = 'runtime.ruby.class_count'.freeze
+        METRIC_GC_PREFIX = 'runtime.ruby.gc'.freeze
+        METRIC_THREAD_COUNT = 'runtime.ruby.thread_count'.freeze
+
+        TAG_SERVICE = 'service'.freeze
+      end
     end
   end
 end

lib/ddtrace/metrics.rb

@@ -1,5 +1,6 @@
 require 'ddtrace/ext/metrics'
 
+require 'set'
 require 'ddtrace/utils/time'
 require 'ddtrace/runtime/identity'
 

lib/ddtrace/runtime/gc.rb

@@ -0,0 +1,16 @@
+module Datadog
+  module Runtime
+    # Retrieves garbage collection statistics
+    module GC
+      module_function
+
+      def stat
+        ::GC.stat
+      end
+
+      def available?
+        defined?(::GC) && ::GC.respond_to?(:stat)
+      end
+    end
+  end
+end

lib/ddtrace/runtime/metrics.rb

@@ -1,26 +1,90 @@
 require 'ddtrace/ext/runtime'
+
+require 'ddtrace/metrics'
 require 'ddtrace/runtime/class_count'
-require 'ddtrace/runtime/heap_size'
+require 'ddtrace/runtime/gc'
+require 'ddtrace/runtime/identity'
 require 'ddtrace/runtime/thread_count'
 
 module Datadog
   module Runtime
     # For generating runtime metrics
-    module Metrics
-      module_function
+    class Metrics < Datadog::Metrics
+      def initialize(*args)
+        super
+
+        # Initialize service list
+        @services = Set.new
+        @service_tags = nil
+      end
 
-      # Flush all runtime metrics to a Datadog::Metrics instance.
-      def flush(metrics = Datadog.metrics)
-        try_flush { metrics.gauge(Ext::Runtime::METRIC_CLASS_COUNT, ClassCount.value) if ClassCount.available? }
-        try_flush { metrics.gauge(Ext::Runtime::METRIC_HEAP_SIZE, HeapSize.value) if HeapSize.available? }
-        try_flush { metrics.gauge(Ext::Runtime::METRIC_THREAD_COUNT, ThreadCount.value) if ThreadCount.available? }
+      def associate_with_span(span)
+        return if span.nil?
+
+        # Register service as associated with metrics
+        register_service(span.service) unless span.service.nil?
+
+        # Tag span with language and runtime ID for association with metrics
+        span.set_metric(Ext::Runtime::TAG_LANG, Runtime::Identity.lang)
+        span.set_metric(Ext::Runtime::TAG_RUNTIME_ID, Runtime::Identity.id)
+      end
+
+      # Associate service with runtime metrics
+      def register_service(service)
+        return if service.nil?
+
+        service = service.to_s
+
+        unless @services.include?(service)
+          # Add service to list and update services tag
+          services << service
+
+          # Recompile the service tags
+          compile_service_tags!
+        end
+      end
+
+      # Flush all runtime metrics to Statsd client
+      def flush
+        try_flush { gauge(Ext::Runtime::Metrics::METRIC_CLASS_COUNT, ClassCount.value) if ClassCount.available? }
+        try_flush { gauge(Ext::Runtime::Metrics::METRIC_THREAD_COUNT, ThreadCount.value) if ThreadCount.available? }
+        try_flush { gc_metrics.each { |metric, value| gauge(metric, value) } if GC.available? }
+      end
+
+      def gc_metrics
+        GC.stat.map do |k, v|
+          ["#{Ext::Runtime::Metrics::METRIC_GC_PREFIX}.#{k}", v]
+        end.to_h
       end
 
       def try_flush
         yield
       rescue StandardError => e
         Datadog::Tracer.log.error("Error while sending runtime metric. Cause: #{e.message}")
       end
+
+      def default_metric_options
+        # Return dupes, so that the constant isn't modified,
+        # and defaults are unfrozen for mutation in Statsd.
+        super.tap do |options|
+          options[:tags] = options[:tags].dup
+
+          # Add services dynamically because they might change during runtime.
+          options[:tags].concat(service_tags) unless service_tags.nil?
+        end
+      end
+
+      private
+
+      attr_reader \
+        :service_tags,
+        :services
+
+      def compile_service_tags!
+        @service_tags = services.to_a.collect do |service|
+          "#{Ext::Runtime::Metrics::TAG_SERVICE}:#{service}".freeze
+        end
+      end
     end
   end
 end

lib/ddtrace/workers.rb

@@ -64,10 +64,10 @@ def callback_services
       end
 
       def callback_runtime_metrics
-        return true unless Datadog.metrics.send_stats?
+        return true unless Datadog.runtime_metrics.send_stats?
 
         begin
-          Datadog::Runtime::Metrics.flush(Datadog.metrics)
+          Datadog.runtime_metrics.flush
         rescue StandardError => e
           # ensures that the thread will not die because of an exception.
           # TODO[manu]: findout the reason and reschedule the send if it's not

spec/ddtrace/runtime/gc_spec.rb

@@ -0,0 +1,16 @@
+# encoding: utf-8
+
+require 'spec_helper'
+require 'ddtrace/runtime/gc'
+
+RSpec.describe Datadog::Runtime::GC do
+  describe '::stat' do
+    subject(:stat) { described_class.stat }
+    it { is_expected.to be_a_kind_of(Hash) }
+  end
+
+  describe '::available?' do
+    subject(:available?) { described_class.available? }
+    it { is_expected.to be true }
+  end
+end