feat: Emit provider events from LaunchDarkly client status

lib/ldclient-openfeature.rb

@@ -2,6 +2,7 @@
 
 require_relative "ldclient-openfeature/impl/context_converter"
 require_relative "ldclient-openfeature/impl/details_converter"
+require_relative "ldclient-openfeature/impl/event_listeners"
 require_relative "ldclient-openfeature/provider"
 require_relative "ldclient-openfeature/version"
 

lib/ldclient-openfeature/impl/event_listeners.rb

@@ -0,0 +1,82 @@
+# frozen_string_literal: true
+
+require 'ldclient-rb'
+require 'open_feature/sdk'
+
+module LaunchDarkly
+  module OpenFeature
+    module Impl
+      #
+      # Translates LaunchDarkly data source status changes into OpenFeature provider events.
+      #
+      class DataSourceStatusListener
+        #
+        # @param provider [LaunchDarkly::OpenFeature::Provider]
+        #
+        def initialize(provider)
+          @provider = provider
+        end
+
+        #
+        # @param status [LaunchDarkly::Interfaces::DataSource::Status]
+        #
+        # @return [void]
+        #
+        def update(status)
+          case status.state
+          when ::LaunchDarkly::Interfaces::DataSource::Status::VALID
+            @provider.emit_event(::OpenFeature::SDK::ProviderEvent::PROVIDER_READY)
+          when ::LaunchDarkly::Interfaces::DataSource::Status::INTERRUPTED
+            @provider.emit_event(
+              ::OpenFeature::SDK::ProviderEvent::PROVIDER_STALE,
+              message: message(status, "the data source has been interrupted")
+            )
+          when ::LaunchDarkly::Interfaces::DataSource::Status::OFF
+            @provider.emit_event(
+              ::OpenFeature::SDK::ProviderEvent::PROVIDER_ERROR,
+              error_code: ::OpenFeature::SDK::Provider::ErrorCode::GENERAL,
+              message: message(status, "the data source has been permanently shut down")
+            )
+          end
+        end
+
+        #
+        # @param status [LaunchDarkly::Interfaces::DataSource::Status]
+        # @param fallback [String]
+        #
+        # @return [String]
+        #
+        private def message(status, fallback)
+          error = status.last_error
+          return fallback if error.nil?
+
+          "#{fallback}: #{error.kind} #{error.status_code} #{error.message}".strip
+        end
+      end
+
+      #
+      # Translates LaunchDarkly flag change events into OpenFeature configuration changed events.
+      #
+      class FlagChangeListener
+        #
+        # @param provider [LaunchDarkly::OpenFeature::Provider]
+        #
+        def initialize(provider)
+          @provider = provider
+        end
+
+        #
+        # @param flag_change [LaunchDarkly::Interfaces::FlagChange]
+        #
+        # @return [void]
+        #
+        def update(flag_change)
+          @provider.emit_event(
+            ::OpenFeature::SDK::ProviderEvent::PROVIDER_CONFIGURATION_CHANGED,
+            flags_changed: [flag_change.key]
+          )
+        end
+      end
+    end
+  end
+end

lib/ldclient-openfeature/provider.rb

@@ -6,6 +6,8 @@
 module LaunchDarkly
   module OpenFeature
     class Provider
+      include ::OpenFeature::SDK::Provider::EventEmitter
+
       #
       # Retrieve metadata information describing this provider.
       #
@@ -37,6 +39,9 @@ def initialize(sdk_key, config = LaunchDarkly::Config.default, wait_for_seconds
         @details_converter = Impl::ResolutionDetailsConverter.new
 
         @metadata = ::OpenFeature::SDK::Provider::ProviderMetadata.new(name: "launchdarkly-openfeature-server").freeze
+
+        @client.data_source_status_provider.add_listener(Impl::DataSourceStatusListener.new(self))
+        @client.flag_tracker.add_listener(Impl::FlagChangeListener.new(self))
       end
 
       def fetch_boolean_value(flag_key:, default_value:, evaluation_context: nil)

spec/impl/data_source_status_listener_spec.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+RSpec.describe LaunchDarkly::OpenFeature::Impl::DataSourceStatusListener do
+  let(:provider) { double(emit_event: nil) }
+  let(:listener) { described_class.new(provider) }
+
+  def status(state, error = nil)
+    LaunchDarkly::Interfaces::DataSource::Status.new(state, Time.now, error)
+  end
+
+  it "a valid data source is ready" do
+    listener.update(status(LaunchDarkly::Interfaces::DataSource::Status::VALID))
+
+    expect(provider).to have_received(:emit_event).with(OpenFeature::SDK::ProviderEvent::PROVIDER_READY)
+  end
+
+  it "an interrupted data source is stale" do
+    listener.update(status(LaunchDarkly::Interfaces::DataSource::Status::INTERRUPTED))
+
+    expect(provider).to have_received(:emit_event)
+      .with(OpenFeature::SDK::ProviderEvent::PROVIDER_STALE, hash_including(:message))
+  end
+
+  it "a shut down data source is an error" do
+    error = LaunchDarkly::Interfaces::DataSource::ErrorInfo.new(
+      LaunchDarkly::Interfaces::DataSource::ErrorInfo::ERROR_RESPONSE, 401, "Unauthorized", Time.now
+    )
+
+    listener.update(status(LaunchDarkly::Interfaces::DataSource::Status::OFF, error))
+
+    expect(provider).to have_received(:emit_event).with(
+      OpenFeature::SDK::ProviderEvent::PROVIDER_ERROR,
+      hash_including(error_code: OpenFeature::SDK::Provider::ErrorCode::GENERAL, message: /401/)
+    )
+  end
+
+  it "an initializing data source does not emit an event" do
+    listener.update(status(LaunchDarkly::Interfaces::DataSource::Status::INITIALIZING))
+
+    expect(provider).not_to have_received(:emit_event)
+  end
+end

spec/impl/flag_change_listener_spec.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+RSpec.describe LaunchDarkly::OpenFeature::Impl::FlagChangeListener do
+  let(:provider) { double(emit_event: nil) }
+
+  it "a flag change is a configuration change" do
+    described_class.new(provider).update(LaunchDarkly::Interfaces::FlagChange.new("flag-key"))
+
+    expect(provider).to have_received(:emit_event).with(
+      OpenFeature::SDK::ProviderEvent::PROVIDER_CONFIGURATION_CHANGED,
+      flags_changed: ["flag-key"]
+    )
+  end
+end