Implement TracerFactory (#114)

api/lib/opentelemetry.rb

@@ -17,13 +17,14 @@
 module OpenTelemetry
   extend self
 
-  attr_writer :tracer, :meter, :distributed_context_manager
+  attr_writer :tracer_factory, :meter, :distributed_context_manager
 
   attr_accessor :logger
-  # @return [Object, Trace::Tracer] registered tracer or a default no-op
-  #   implementation of the tracer
-  def tracer
-    @tracer ||= Trace::Tracer.new
+
+  # @return [Object, Trace::TracerFactory] registered tracer factory or a
+  #   default no-op implementation of the tracer factory.
+  def tracer_factory
+    @tracer_factory ||= Trace::TracerFactory.new
   end
 
   # @return [Object, Metrics::Meter] registered meter or a default no-op

api/lib/opentelemetry/trace.rb

@@ -50,3 +50,4 @@ def self.generate_span_id
 require 'opentelemetry/trace/sampling_hint'
 require 'opentelemetry/trace/status'
 require 'opentelemetry/trace/tracer'
+require 'opentelemetry/trace/tracer_factory'

api/lib/opentelemetry/trace/tracer_factory.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+module OpenTelemetry
+  module Trace
+    # No-op implementation of a tracer factory.
+    class TracerFactory
+      # Returns a {Tracer} instance.
+      #
+      # @param [optional String] name Instrumentation package name
+      # @param [optional String] version Instrumentation package version
+      #
+      # @return [Tracer]
+      def tracer(name = nil, version = nil)
+        @tracer ||= Tracer.new
+      end
+    end
+  end
+end

api/test/opentelemetry/trace/tracer_factory_test.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+require 'test_helper'
+
+describe OpenTelemetry::Trace::TracerFactory do
+  let(:tracer_factory) { OpenTelemetry::Trace::TracerFactory.new }
+
+  describe '.tracer' do
+    it 'returns the same tracer for the same arguments' do
+      tracer1 = tracer_factory.tracer('component', 'semver:1.0')
+      tracer2 = tracer_factory.tracer('component', 'semver:1.0')
+      _(tracer1).must_equal(tracer2)
+    end
+  end
+end

api/test/opentelemetry_test.rb

@@ -8,25 +8,25 @@
 require 'tempfile'
 
 describe OpenTelemetry do
-  describe '.tracer' do
+  describe '.tracer_factory' do
     after do
-      # Ensure we don't leak custom tracers to other tests
-      OpenTelemetry.tracer = nil
+      # Ensure we don't leak custom tracer factories and tracers to other tests
+      OpenTelemetry.tracer_factory = nil
     end
 
-    it 'returns instance of Trace::Tracer by default' do
-      tracer = OpenTelemetry.tracer
-      tracer.must_be_instance_of(OpenTelemetry::Trace::Tracer)
+    it 'returns instance of Trace::TracerFactory by default' do
+      tracer_factory = OpenTelemetry.tracer_factory
+      _(tracer_factory).must_be_instance_of(OpenTelemetry::Trace::TracerFactory)
     end
 
     it 'returns the same instance when accessed multiple times' do
-      OpenTelemetry.tracer.must_equal(OpenTelemetry.tracer)
+      _(OpenTelemetry.tracer_factory).must_equal(OpenTelemetry.tracer_factory)
     end
 
-    it 'returns user specified tracer' do
-      custom_tracer = 'a custom tracer'
-      OpenTelemetry.tracer = custom_tracer
-      OpenTelemetry.tracer.must_equal(custom_tracer)
+    it 'returns user specified tracer factory' do
+      custom_tracer_factory = 'a custom tracer factory'
+      OpenTelemetry.tracer_factory = custom_tracer_factory
+      _(OpenTelemetry.tracer_factory).must_equal(custom_tracer_factory)
     end
   end
 

sdk/lib/opentelemetry/sdk/trace.rb

@@ -21,3 +21,4 @@ module Trace
 require 'opentelemetry/sdk/trace/span_data'
 require 'opentelemetry/sdk/trace/span'
 require 'opentelemetry/sdk/trace/tracer'
+require 'opentelemetry/sdk/trace/tracer_factory'

sdk/lib/opentelemetry/sdk/trace/tracer.rb

@@ -11,11 +11,20 @@ module Trace
       class Tracer < OpenTelemetry::Trace::Tracer
         attr_accessor :active_trace_config
         attr_accessor :resource # TODO: should this be read-only? If not, how should exporters know when it is updated?
+        attr_reader :name
+        attr_reader :version
 
+        # @api private
+        #
         # Returns a new {Tracer} instance.
         #
+        # @param [String] name Instrumentation package name
+        # @param [String] version Instrumentation package version
+        #
         # @return [Tracer]
-        def initialize
+        def initialize(name, version)
+          @name = name
+          @version = version
           @active_span_processor = NoopSpanProcessor.instance
           @active_trace_config = Config::TraceConfig::DEFAULT
           @registered_span_processors = []

sdk/lib/opentelemetry/sdk/trace/tracer_factory.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+module OpenTelemetry
+  module SDK
+    module Trace
+      # No-op implementation of a tracer factory.
+      class TracerFactory
+        Key = Struct.new(:name, :version)
+        private_constant(:Key)
+
+        # Returns a new {TracerFactory} instance.
+        #
+        # @return [TracerFactory]
+        def initialize
+          @mutex = Mutex.new
+          @registry = {}
+        end
+
+        # Returns a {Tracer} instance.
+        #
+        # @param [optional String] name Instrumentation package name
+        # @param [optional String] version Instrumentation package version
+        #
+        # @return [Tracer]
+        def tracer(name = nil, version = nil)
+          name ||= ''
+          version ||= ''
+          @mutex.synchronize { @registry[Key.new(name, version)] ||= Tracer.new(name, version) }
+        end
+      end
+    end
+  end
+end

sdk/test/opentelemetry/sdk/trace/tracer_factory_test.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+require 'test_helper'
+
+describe OpenTelemetry::SDK::Trace::TracerFactory do
+  let(:tracer_factory) { OpenTelemetry::SDK::Trace::TracerFactory.new }
+
+  describe '.tracer' do
+    it 'returns the same tracer for the same arguments' do
+      tracer1 = tracer_factory.tracer('component', 'semver:1.0')
+      tracer2 = tracer_factory.tracer('component', 'semver:1.0')
+      _(tracer1).must_equal(tracer2)
+    end
+
+    it 'returns a default name-less version-less tracer' do
+      tracer = tracer_factory.tracer
+      _(tracer.name).must_equal('')
+      _(tracer.version).must_equal('')
+    end
+
+    it 'returns different tracers for different names' do
+      tracer1 = tracer_factory.tracer('component1', 'semver:1.0')
+      tracer2 = tracer_factory.tracer('component2', 'semver:1.0')
+      _(tracer1).wont_equal(tracer2)
+    end
+
+    it 'returns different tracers for different versions' do
+      tracer1 = tracer_factory.tracer('component', 'semver:1.0')
+      tracer2 = tracer_factory.tracer('component', 'semver:2.0')
+      _(tracer1).wont_equal(tracer2)
+    end
+  end
+end

sdk/test/opentelemetry/sdk/trace/tracer_test.rb

@@ -9,18 +9,30 @@
 describe OpenTelemetry::SDK::Trace::Tracer do
   Tracer = OpenTelemetry::SDK::Trace::Tracer
 
-  let(:tracer) { Tracer.new }
+  let(:tracer) { Tracer.new('', '') }
   let(:record_sampler) do
     ->(trace_id:, span_id:, parent_context:, hint:, links:, name:, kind:, attributes:) { Result.new(decision: Decision::RECORD) } # rubocop:disable Lint/UnusedBlockArgument
   end
 
   describe '#initialize' do
     it 'installs a Resource' do
-      Tracer.new.resource.wont_be_nil
+      _(Tracer.new(nil, nil).resource).wont_be_nil
     end
 
     it 'activates a default TraceConfig' do
-      Tracer.new.active_trace_config.must_equal(TraceConfig::DEFAULT)
+      _(Tracer.new(nil, nil).active_trace_config).must_equal(TraceConfig::DEFAULT)
+    end
+  end
+
+  describe '#name' do
+    it 'reflects the name passed in' do
+      _(Tracer.new('component', nil).name).must_equal('component')
+    end
+  end
+
+  describe '#version' do
+    it 'reflects the version passed in' do
+      _(Tracer.new(nil, 'semver:1.0').version).must_equal('semver:1.0')
     end
   end