Log instrument registry

logs_api/lib/opentelemetry/logs/logger.rb

@@ -8,6 +8,11 @@ module OpenTelemetry
   module Logs
     # No-op implementation of logger.
     class Logger
+      def initialize
+        @mutex = Mutex.new
+        @instrument_registry = {}
+      end
+
       # rubocop:disable Style/EmptyMethod
 
       # Emit a {LogRecord} to the processing pipeline.

logs_api/lib/opentelemetry/logs/logger_provider.rb

@@ -9,7 +9,9 @@ module Logs
     # No-op implementation of a logger provider.
     class LoggerProvider
       NOOP_LOGGER = OpenTelemetry::Logs::Logger.new
-      private_constant :NOOP_LOGGER
+      # TODO: Make NOOP_LOGGER private again
+      # NOOP_LOGGER is used in the SDK logger at this time until the ProxyLogger has been created
+      # private_constant :NOOP_LOGGER
 
       # Returns an {OpenTelemetry::Logs::Logger} instance.
       #

logs_sdk/lib/opentelemetry/sdk/logs/logger_provider.rb

@@ -9,6 +9,9 @@ module SDK
     module Logs
       # The SDK implementation of OpenTelemetry::Logs::LoggerProvider.
       class LoggerProvider < OpenTelemetry::Logs::LoggerProvider
+        Key = Struct.new(:name, :version)
+        private_constant(:Key)
+
         UNEXPECTED_ERROR_MESSAGE = 'unexpected error in ' \
           'OpenTelemetry::SDK::Logs::LoggerProvider#%s'
 
@@ -25,6 +28,8 @@ def initialize(resource: OpenTelemetry::SDK::Resources::Resource.create)
           @mutex = Mutex.new
           @resource = resource
           @stopped = false
+          @registry = {}
+          @registry_mutex = Mutex.new
         end
 
         # Returns an {OpenTelemetry::SDK::Logs::Logger} instance.
@@ -34,14 +39,22 @@ def initialize(resource: OpenTelemetry::SDK::Resources::Resource.create)
         #
         # @return [OpenTelemetry::SDK::Logs::Logger]
         def logger(name:, version: nil)
-          version ||= ''
+          if @stopped
+            # TODO: Return a ProxyLogger instead once that's available
+            OpenTelemetry.logger.warn('calling LoggerProvider#logger after shutdown, a noop logger will be returned')
+            OpenTelemetry::Logs::LoggerProvider::NOOP_LOGGER
+          else
+            version ||= ''
+
+            if !name.is_a?(String) || name.empty?
+              OpenTelemetry.logger.warn('LoggerProvider#logger called with an ' \
+                "invalid name. Name provided: #{name.inspect}")
+            end
 
-          if !name.is_a?(String) || name.empty?
-            OpenTelemetry.logger.warn('LoggerProvider#logger called with an ' \
-              "invalid name. Name provided: #{name.inspect}")
+            @registry_mutex.synchronize do
+              @registry[Key.new(name, version)] ||= Logger.new(name, version, self)
+            end
           end
-
-          Logger.new(name, version, self)
         end
 
         # Adds a new log record processor to this LoggerProvider's

logs_sdk/test/opentelemetry/sdk/logs/logger_provider_test.rb

@@ -215,4 +215,40 @@ def mock_context.value(key); OpenTelemetry::Trace::Span::INVALID; end # rubocop:
       end
     end
   end
+
+  describe 'instrument registry' do
+    # On the first call, create a logger with an empty string for name and
+    # version and add to the registry. The second call returns that logger
+    # from the registry instead of creating a new instance.
+    it 'reuses the same logger if called twice when name and version are nil' do
+      logger = logger_provider.logger(name: nil, version: nil)
+      logger2 = logger_provider.logger(name: nil, version: nil)
+
+      assert_instance_of(Logs::Logger, logger)
+      assert_same(logger, logger2)
+    end
+
+    describe 'when stopped' do
+      it 'logs a warning' do
+        logger_provider.instance_variable_set(:@stopped, true)
+
+        OpenTelemetry::TestHelpers.with_test_logger do |log_stream|
+          logger_provider.logger(name: '')
+          assert_match(
+            /calling LoggerProvider#logger after shutdown/,
+            log_stream.string
+          )
+        end
+      end
+
+      it 'does not add a new logger to the registry' do
+        before_stopped_size = logger_provider.instance_variable_get(:@registry).keys.size
+        logger_provider.instance_variable_set(:@stopped, true)
+        logger_provider.logger(name: 'new_logger')
+        after_stopped_size = logger_provider.instance_variable_get(:@registry).keys.size
+
+        assert_equal(before_stopped_size, after_stopped_size)
+      end
+    end
+  end
 end