chore: Create FDv1 datasystem implementation

Author: jsonbailey

lib/ldclient-rb/impl/datasource/null_processor.rb

@@ -0,0 +1,53 @@
+require 'concurrent'
+
+module LaunchDarkly
+  module Impl
+    module DataSource
+      #
+      # A minimal UpdateProcessor implementation used when the SDK is in offline mode
+      # or daemon (LDD) mode. It does nothing except mark itself as initialized.
+      #
+      # @private
+      #
+      class NullUpdateProcessor
+        include LaunchDarkly::Interfaces::DataSource
+
+        #
+        # Creates a new NullUpdateProcessor.
+        #
+        def initialize
+          @ready = Concurrent::Event.new
+        end
+
+        #
+        # Starts the data source. Since this is a null implementation, it immediately
+        # sets the ready event to indicate initialization is complete.
+        #
+        # @return [Concurrent::Event] The ready event
+        #
+        def start
+          @ready.set
+          @ready
+        end
+
+        #
+        # Stops the data source. This is a no-op for the null implementation.
+        #
+        # @return [void]
+        #
+        def stop
+          # Nothing to do
+        end
+
+        #
+        # Checks if the data source has been initialized.
+        #
+        # @return [Boolean] Always returns true since this is a null implementation
+        #
+        def initialized?
+          true
+        end
+      end
+    end
+  end
+end

lib/ldclient-rb/impl/datasystem.rb

@@ -19,13 +19,12 @@ module DataSystem
       #
       # Starts the data system.
       #
-      # This method will return immediately. The provided event will be set when the system
+      # This method will return immediately. The returned event will be set when the system
       # has reached an initial state (either permanently failed, e.g. due to bad auth, or succeeded).
       #
-      # @param ready_event [Concurrent::Event] Event to set when initialization is complete
-      # @return [void]
+      # @return [Concurrent::Event] Event that will be set when initialization is complete
       #
-      def start(ready_event)
+      def start
         raise NotImplementedError, "#{self.class} must implement #start"
       end
 
@@ -117,6 +116,17 @@ def set_flag_value_eval_fn(eval_fn)
         raise NotImplementedError, "#{self.class} must implement #set_flag_value_eval_fn"
       end
 
+      #
+      # Sets the diagnostic accumulator for streaming initialization metrics.
+      # This should be called before start() to ensure metrics are collected.
+      #
+      # @param diagnostic_accumulator [DiagnosticAccumulator] The diagnostic accumulator
+      # @return [void]
+      #
+      def set_diagnostic_accumulator(diagnostic_accumulator)
+        raise NotImplementedError, "#{self.class} must implement #set_diagnostic_accumulator"
+      end
+
       #
       # Represents the availability of data in the SDK.
       #

lib/ldclient-rb/impl/datasystem/fdv1.rb

@@ -0,0 +1,227 @@
+require 'concurrent'
+require 'ldclient-rb/impl/datasystem'
+require 'ldclient-rb/impl/data_source'
+require 'ldclient-rb/impl/data_store'
+require 'ldclient-rb/impl/datasource/null_processor'
+require 'ldclient-rb/impl/flag_tracker'
+require 'ldclient-rb/impl/broadcaster'
+
+module LaunchDarkly
+  module Impl
+    module DataSystem
+      #
+      # FDv1 wires the existing v1 data source and store behavior behind the
+      # generic DataSystem surface.
+      #
+      # @private
+      #
+      class FDv1
+        include LaunchDarkly::Impl::DataSystem
+
+        #
+        # Creates a new FDv1 data system.
+        #
+        # @param sdk_key [String] The SDK key
+        # @param config [LaunchDarkly::Config] The SDK configuration
+        #
+        def initialize(sdk_key, config)
+          @sdk_key = sdk_key
+          @config = config
+          @shared_executor = Concurrent::SingleThreadExecutor.new
+
+          # Set up data store plumbing
+          @data_store_broadcaster = LaunchDarkly::Impl::Broadcaster.new(@shared_executor, @config.logger)
+          @data_store_update_sink = LaunchDarkly::Impl::DataStore::UpdateSink.new(
+            @data_store_broadcaster
+          )
+
+          # Wrap the data store with client wrapper (must be created before status provider)
+          @store_wrapper = LaunchDarkly::Impl::FeatureStoreClientWrapper.new(
+            @config.feature_store,
+            @data_store_update_sink,
+            @config.logger
+          )
+
+          # Create status provider with store wrapper
+          @data_store_status_provider = LaunchDarkly::Impl::DataStore::StatusProvider.new(
+            @store_wrapper,
+            @data_store_update_sink
+          )
+
+          # Set up data source plumbing
+          @data_source_broadcaster = LaunchDarkly::Impl::Broadcaster.new(@shared_executor, @config.logger)
+          @flag_change_broadcaster = LaunchDarkly::Impl::Broadcaster.new(@shared_executor, @config.logger)
+          @flag_tracker_impl = LaunchDarkly::Impl::FlagTracker.new(
+            @flag_change_broadcaster,
+            lambda { |_key, _context| nil } # Replaced by client to use its evaluation method
+          )
+          @data_source_update_sink = LaunchDarkly::Impl::DataSource::UpdateSink.new(
+            @store_wrapper,
+            @data_source_broadcaster,
+            @flag_change_broadcaster
+          )
+          @data_source_status_provider = LaunchDarkly::Impl::DataSource::StatusProvider.new(
+            @data_source_broadcaster,
+            @data_source_update_sink
+          )
+
+          # Ensure v1 processors can find the sink via config for status updates
+          @config.data_source_update_sink = @data_source_update_sink
+
+          # Update processor created in start(), because it needs the ready event
+          @update_processor = nil
+
+          # Diagnostic accumulator provided by client for streaming metrics
+          @diagnostic_accumulator = nil
+        end
+
+        #
+        # Starts the v1 update processor and returns immediately. The returned event
+        # will be set by the processor upon first successful initialization or upon permanent failure.
+        #
+        # @return [Concurrent::Event] Event that will be set when initialization is complete
+        #
+        def start
+          @update_processor = make_update_processor
+          @update_processor.start
+        end
+
+        #
+        # Halts the data system, stopping the update processor and shutting down the executor.
+        #
+        # @return [void]
+        #
+        def stop
+          @update_processor&.stop
+          @shared_executor.shutdown
+        end
+
+        #
+        # Returns the feature store wrapper used by this data system.
+        #
+        # @return [LaunchDarkly::Impl::DataStore::ClientWrapper]
+        #
+        def store
+          @store_wrapper
+        end
+
+        #
+        # Injects the flag value evaluation function used by the flag tracker to
+        # compute FlagValueChange events. The function signature should be
+        # (key, context) -> value.
+        #
+        # @param eval_fn [Proc] The evaluation function
+        # @return [void]
+        #
+        def set_flag_value_eval_fn(eval_fn)
+          @flag_tracker_impl = LaunchDarkly::Impl::FlagTracker.new(@flag_change_broadcaster, eval_fn)
+        end
+
+        #
+        # Sets the diagnostic accumulator for streaming initialization metrics.
+        # This should be called before start() to ensure metrics are collected.
+        #
+        # @param diagnostic_accumulator [DiagnosticAccumulator] The diagnostic accumulator
+        # @return [void]
+        #
+        def set_diagnostic_accumulator(diagnostic_accumulator)
+          @diagnostic_accumulator = diagnostic_accumulator
+        end
+
+        #
+        # Returns the data source status provider.
+        #
+        # @return [LaunchDarkly::Interfaces::DataSource::StatusProvider]
+        #
+        def data_source_status_provider
+          @data_source_status_provider
+        end
+
+        #
+        # Returns the data store status provider.
+        #
+        # @return [LaunchDarkly::Interfaces::DataStore::StatusProvider]
+        #
+        def data_store_status_provider
+          @data_store_status_provider
+        end
+
+        #
+        # Returns the flag tracker.
+        #
+        # @return [LaunchDarkly::Interfaces::FlagTracker]
+        #
+        def flag_tracker
+          @flag_tracker_impl
+        end
+
+        #
+        # Indicates what form of data is currently available.
+        #
+        # This is calculated dynamically based on current system state.
+        #
+        # @return [Symbol] One of DataAvailability constants
+        #
+        def data_availability
+          if @config.offline?
+            return DataAvailability::DEFAULTS
+          end
+
+          if @update_processor && @update_processor.initialized?
+            return DataAvailability::REFRESHED
+          end
+
+          if @store_wrapper.initialized?
+            return DataAvailability::CACHED
+          end
+
+          DataAvailability::DEFAULTS
+        end
+
+        #
+        # Indicates the ideal form of data attainable given the current configuration.
+        #
+        # @return [Symbol] One of DataAvailability constants
+        #
+        def target_availability
+          if @config.offline?
+            return DataAvailability::DEFAULTS
+          end
+          # In LDD mode or normal connected modes, the ideal is to be refreshed
+          DataAvailability::REFRESHED
+        end
+
+        #
+        # Creates the appropriate update processor based on the configuration.
+        #
+        # @return [Object] The update processor
+        #
+        private def make_update_processor
+          # Handle custom data source (factory or instance)
+          if @config.data_source
+            return @config.data_source unless @config.data_source.respond_to?(:call)
+
+            # Factory - call with appropriate arity
+            return @config.data_source.arity == 3 ?
+              @config.data_source.call(@sdk_key, @config, @diagnostic_accumulator) :
+              @config.data_source.call(@sdk_key, @config)
+          end
+
+          # Create default data source based on config
+          return LaunchDarkly::Impl::DataSource::NullUpdateProcessor.new if @config.offline? || @config.use_ldd?
+
+          if @config.stream?
+            require 'ldclient-rb/stream'
+            return LaunchDarkly::StreamProcessor.new(@sdk_key, @config, @diagnostic_accumulator)
+          end
+
+          # Polling processor
+          require 'ldclient-rb/polling'
+          requestor = LaunchDarkly::Requestor.new(@sdk_key, @config)
+          LaunchDarkly::PollingProcessor.new(@config, requestor)
+        end
+      end
+    end
+  end
+end
+

lib/ldclient-rb/ldclient.rb

@@ -2,6 +2,7 @@
 require "ldclient-rb/impl/broadcaster"
 require "ldclient-rb/impl/data_source"
 require "ldclient-rb/impl/data_store"
+require "ldclient-rb/impl/datasource/null_processor"
 require "ldclient-rb/impl/diagnostic_events"
 require "ldclient-rb/impl/evaluator"
 require "ldclient-rb/impl/evaluation_with_hook_result"
@@ -132,7 +133,7 @@ def postfork(wait_for_sec = 5)
 
       if @config.use_ldd?
         @config.logger.info { "[LDClient] Started LaunchDarkly Client in LDD mode" }
-        @data_source = NullUpdateProcessor.new
+        @data_source = LaunchDarkly::Impl::DataSource::NullUpdateProcessor.new
         return  # requestor and update processor are not used in this mode
       end
 
@@ -710,7 +711,7 @@ def close
 
     def create_default_data_source(sdk_key, config, diagnostic_accumulator)
       if config.offline?
-        return NullUpdateProcessor.new
+        return LaunchDarkly::Impl::DataSource::NullUpdateProcessor.new
       end
       raise ArgumentError, "sdk_key must not be nil" if sdk_key.nil?  # see LDClient constructor comment on sdk_key
       if config.stream?
@@ -877,23 +878,4 @@ def evaluate_internal(key, context, default, with_reasons)
       false
     end
   end
-
-  #
-  # Used internally when the client is offline.
-  # @private
-  #
-  class NullUpdateProcessor
-    def start
-      e = Concurrent::Event.new
-      e.set
-      e
-    end
-
-    def initialized?
-      true
-    end
-
-    def stop
-    end
-  end
 end