feat: Make API's NoopTextMapPropagator private (#841)

* feat: Make API's NoopTextMapPropagator private

To do so, we wholesale duplicate it into the SDK.

* Shroud our private APIs in mystery

* Move SDK private NoopTextMapPropagator directly into Configurator

Co-authored-by: Francis Bogsanyi <[email protected]>

Author: ahayworth

api/lib/opentelemetry/context/propagation/noop_text_map_propagator.rb

@@ -7,41 +7,17 @@
 module OpenTelemetry
   class Context
     module Propagation
-      # A no-op text map propagator implementation
+      # @api private
       class NoopTextMapPropagator
         EMPTY_LIST = [].freeze
         private_constant(:EMPTY_LIST)
 
-        # Injects the provided context into a carrier.
-        #
-        # @param [Object] carrier A mutable carrier to inject context into.
-        # @param [optional Context] context Context to be injected into carrier. Defaults
-        #   to +Context.current+.
-        # @param [optional Setter] setter If the optional setter is provided, it
-        #   will be used to write context into the carrier, otherwise the default
-        #   setter will be used.
         def inject(carrier, context: Context.current, setter: Context::Propagation.text_map_setter); end
 
-        # Extracts and returns context from a carrier. Returns the provided
-        # context and logs a warning if an error if extraction fails.
-        #
-        # @param [Object] carrier The carrier to extract context from.
-        # @param [optional Context] context Context to be updated with the state
-        #   extracted from the carrier. Defaults to +Context.current+.
-        # @param [optional Getter] getter If the optional getter is provided, it
-        #   will be used to read the header from the carrier, otherwise the default
-        #   getter will be used.
-        #
-        # @return [Context] a new context updated with state extracted from the
-        #   carrier
         def extract(carrier, context: Context.current, getter: Context::Propagation.text_map_getter)
           context
         end
 
-        # Returns the predefined propagation fields. If your carrier is reused, you
-        # should delete the fields returned by this method before calling +inject+.
-        #
-        # @return [Array<String>] a list of fields that will be used by this propagator.
         def fields
           EMPTY_LIST
         end

sdk/lib/opentelemetry/sdk/configurator.rb

@@ -9,6 +9,22 @@ module SDK
     # The configurator provides defaults and facilitates configuring the
     # SDK for use.
     class Configurator # rubocop:disable Metrics/ClassLength
+      # @api private
+      class NoopTextMapPropagator
+        EMPTY_LIST = [].freeze
+        private_constant(:EMPTY_LIST)
+
+        def inject(carrier, context: Context.current, setter: Context::Propagation.text_map_setter); end
+
+        def extract(carrier, context: Context.current, getter: Context::Propagation.text_map_getter)
+          context
+        end
+
+        def fields
+          EMPTY_LIST
+        end
+      end
+
       USE_MODE_UNSPECIFIED = 0
       USE_MODE_ONE = 1
       USE_MODE_ALL = 2
@@ -179,7 +195,7 @@ def configure_propagation # rubocop:disable Metrics/CyclomaticComplexity
           when 'ottrace' then fetch_propagator(propagator, 'OpenTelemetry::Propagator::OTTrace')
           else
             OpenTelemetry.logger.warn "The #{propagator} propagator is unknown and cannot be configured"
-            Context::Propagation::NoopTextMapPropagator.new
+            NoopTextMapPropagator.new
           end
         end
         OpenTelemetry.propagation = Context::Propagation::CompositeTextMapPropagator.compose_propagators((@propagators || propagators).compact)

sdk/test/opentelemetry/sdk/configurator_test.rb

@@ -146,7 +146,7 @@
       end
 
       it 'is user settable' do
-        propagator = OpenTelemetry::Context::Propagation::NoopTextMapPropagator.new
+        propagator = OpenTelemetry::SDK::Configurator::NoopTextMapPropagator.new
         configurator.propagators = [propagator]
         configurator.configure
 
@@ -167,7 +167,7 @@
         end
 
         _(OpenTelemetry.propagation).must_be_instance_of(
-          Context::Propagation::NoopTextMapPropagator
+          OpenTelemetry::SDK::Configurator::NoopTextMapPropagator
         )
       end
     end