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config.go

@@ -216,5 +216,22 @@ type Config struct {
 	//    requests to LaunchDarkly's global CDN (Secondary Synchronizer)
 	// 5. After a period of time, the SDK will swap back to the realtime Flag Delivery Network if it becomes
 	//    available again.
+	//
+	// The default streaming mode configuration is preferred for most use-cases (DataSystem().StreamingPreferred()).
+	// Sometimes streaming connections are blocked by firewalls or proxies. If this is the case, a polling-only mode
+	// can be configured:
+	//
+	//    config := ld.Config{
+	//        DataSystem: ldcomponents.DataSystem().PollingOnly(),
+	//    }
+	//
+	// If you'd like to load data from a local source to provide redundancy if there is a problem
+	// connecting to LaunchDarkly, you can add a custom initializer:
+	//
+	//    config := ld.Config {
+	// 	  		DataSystem: ldcomponents.DataSystem().PrependInitializers(myCustomInitializer),
+	//    }
+	//
+	// The initializer(s) will run before LaunchDarkly's default initializer.
 	DataSystem subsystems.ComponentConfigurer[subsystems.DataSystemConfiguration]
 }

ldcomponents/data_system_configuration_builder.go

@@ -16,12 +16,8 @@ type DataSystemConfigurationBuilder struct {
 }
 
 func DataSystem() *DataSystemConfigurationBuilder {
-	return &DataSystemConfigurationBuilder{
-		primarySyncBuilder:   ldcomponents.StreamingDataSource(),
-		secondarySyncBuilder: ldcomponents.PollingDataSource(),
-		storeBuilder:         nil, // in-memory only
-		initializerBuilders:  []subsystems.ComponentConfigurer[subsystems.Initializer]{ldcomponents.PollingInitializer()},
-	}
+	d := &DataSystemConfigurationBuilder{}
+	return d.StreamingPreferred()
 }
 
 func (d *DataSystemConfigurationBuilder) Store(store subsystems.ComponentConfigurer[subsystems.DataStore]) *DataSystemConfigurationBuilder {
@@ -34,16 +30,29 @@ func (d *DataSystemConfigurationBuilder) Initializers(initializers ...subsystems
 	return d
 }
 
-func (d *DataSystemConfigurationBuilder) PrimarySynchronizer(sync subsystems.ComponentConfigurer[subsystems.Synchronizer]) *DataSystemConfigurationBuilder {
-	d.primarySyncBuilder = sync
+func (d *DataSystemConfigurationBuilder) PrependInitializers(initializers ...subsystems.ComponentConfigurer[subsystems.Initializer]) *DataSystemConfigurationBuilder {
+	d.initializerBuilders = append(initializers, d.initializerBuilders...)
 	return d
 }
 
-func (d *DataSystemConfigurationBuilder) SecondarySynchronizer(sync subsystems.ComponentConfigurer[subsystems.Synchronizer]) *DataSystemConfigurationBuilder {
-	d.secondarySyncBuilder = sync
+func (d *DataSystemConfigurationBuilder) Synchronizers(primary, secondary subsystems.ComponentConfigurer[subsystems.Synchronizer]) *DataSystemConfigurationBuilder {
+	d.primarySyncBuilder = primary
+	d.secondarySyncBuilder = secondary
 	return d
 }
 
+func (d *DataSystemConfigurationBuilder) PollingOnly() *DataSystemConfigurationBuilder {
+	return d.Synchronizer(ldcomponents.PollingDataSource())
+}
+
+func (d *DataSystemConfigurationBuilder) StreamingPreferred() *DataSystemConfigurationBuilder {
+	return d.Initializers(ldcomponents.PollingInitializer()).Synchronizer(ldcomponents.StreamingDataSource(), ldcomponents.PollingDataSource())
+}
+
+func (d *DataSystemConfigurationBuilder) Synchronizer(sync subsystems.ComponentConfigurer[subsystems.Synchronizer]) *DataSystemConfigurationBuilder {
+	return d.Synchronizers(sync, nil)
+}
+
 func (d *DataSystemConfigurationBuilder) Build(
 	context subsystems.ClientContext,
 ) (subsystems.DataSystemConfiguration, error) {

subsystems/datasystem_configuration.go

@@ -21,17 +21,3 @@ type DataSystemConfiguration struct {
 	Initializers  []Initializer
 	Synchronizers SynchronizersConfiguration
 }
-
-/**
-
-DataSystemConfiguration {
-   Store: ldcomponents.Empty(), || ldcomponents.PersistentStore(
-   Initializers: []ldcomponents.Initializer{
-		ldcomponents.PollFDv2()
-   },
-   Synchronizers: ldcomponents.SynchronizersConfiguration{
-		Primary: ldcomponents.StreamingFDv2(),
-		Secondary: ldcomponents.PollFDv2()
-	}
-}
-*/