FFL-1273 Add NativeEvaluator

Author: dd-oleksii

lib/datadog/open_feature/evaluation_engine.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 require_relative 'ext'
-require_relative 'noop_evaluator'
+require_relative 'native_evaluator'
 require_relative 'resolution_details'
 
 module Datadog
@@ -17,7 +17,7 @@ def initialize(reporter, telemetry:, logger:)
         @telemetry = telemetry
         @logger = logger
 
-        @evaluator = NoopEvaluator.new(nil)
+        @evaluator = NativeEvaluator.new(nil)
       end
 
       def fetch_value(flag_key:, default_value:, expected_type:, evaluation_context: nil)
@@ -45,7 +45,7 @@ def fetch_value(flag_key:, default_value:, expected_type:, evaluation_context: n
       def reconfigure!(configuration)
         @logger.debug('OpenFeature: Removing configuration') if configuration.nil?
 
-        @evaluator = NoopEvaluator.new(configuration)
+        @evaluator = NativeEvaluator.new(configuration)
       rescue => e
         message = 'OpenFeature: Failed to reconfigure, reverting to the previous configuration'
 

lib/datadog/open_feature/native_evaluator.rb

@@ -0,0 +1,73 @@
+# frozen_string_literal: true
+
+require 'json'
+require_relative 'ext'
+require_relative 'resolution_details'
+
+module Datadog
+  module OpenFeature
+    # Evaluation using native extension
+    class NativeEvaluator
+      def initialize(configuration)
+        @libdatadog_api_failure = Datadog::Core::LIBDATADOG_API_FAILURE
+        if configuration && !@libdatadog_api_failure
+          @configuration = Datadog::Core::FeatureFlags::Configuration.new(configuration)
+        end
+      end
+
+      def get_assignment(flag_key, default_value, context, expected_type)
+        return build_fatal_error(default_value) if @libdatadog_api_failure
+
+        configuration = @configuration
+        return build_not_ready_error(default_value) if configuration.nil?
+
+        native_details = configuration.get_assignment(flag_key, expected_type.to_sym, context)
+
+        variant = native_details.variant
+        value = native_details.value
+        if expected_type == 'object' && value.is_a?(String)
+          # JSON flags return value as string. We need to parse it.
+          value = JSON.parse(value)
+        elsif variant.nil?
+          value = default_value
+        end
+
+        ResolutionDetails.new(
+          value: value,
+          variant: variant,
+          allocation_key: native_details.allocation_key,
+          reason: native_details.reason,
+          error?: native_details.error?,
+          error_code: native_details.error_code,
+          error_message: native_details.error_message,
+          log?: native_details.log?,
+          flag_metadata: native_details.flag_metadata,
+        )
+      rescue JSON::ParserError => e
+        ResolutionDetails.build_error(
+          value: default_value,
+          error_code: 'PARSE_ERROR',
+          error_message: "Failed to parse JSON value: #{e.message}"
+        )
+      end
+
+      private
+
+      def build_fatal_error(default_value)
+        ResolutionDetails.build_error(
+          value: default_value,
+          error_code: Ext::PROVIDER_FATAL,
+          error_message: "libdatadog is not available: #{@libdatadog_api_failure}"
+        )
+      end
+
+      def build_not_ready_error(default_value)
+        ResolutionDetails.build_error(
+          value: default_value,
+          error_code: Ext::PROVIDER_NOT_READY,
+          error_message: 'Configuration not available'
+        )
+      end
+    end
+  end
+end

sig/datadog/open_feature/native_evaluator.rbs

@@ -0,0 +1,19 @@
+module Datadog
+  module OpenFeature
+    # Evaluation using native extension
+    class NativeEvaluator
+      @libdatadog_api_failure: String?
+      @configuration: Core::FeatureFlags::Configuration?
+
+      def initialize: (String? configuration) -> void
+
+      def get_assignment: (String flag_key, untyped default_value, Hash[String, untyped] context, String expected_type) -> ResolutionDetails
+
+      private
+
+      def build_fatal_error: (untyped default_value) -> ResolutionDetails
+
+      def build_not_ready_error: (untyped default_value) -> ResolutionDetails
+    end
+  end
+end