GH-233: Add KCL polling config support

Fixes https://github.com/spring-projects/spring-integration-aws/issues/233

src/main/java/org/springframework/integration/aws/inbound/kinesis/KclMessageDrivenChannelAdapter.java

@@ -40,7 +40,6 @@ import software.amazon.kinesis.coordinator.Scheduler;
 import software.amazon.kinesis.exceptions.InvalidStateException;
 import software.amazon.kinesis.exceptions.ShutdownException;
 import software.amazon.kinesis.exceptions.ThrottlingException;
-import software.amazon.kinesis.lifecycle.LifecycleConfig;
 import software.amazon.kinesis.lifecycle.events.InitializationInput;
 import software.amazon.kinesis.lifecycle.events.LeaseLostInput;
 import software.amazon.kinesis.lifecycle.events.ProcessRecordsInput;
@@ -54,7 +53,9 @@ import software.amazon.kinesis.processor.ShardRecordProcessorFactory;
 import software.amazon.kinesis.processor.SingleStreamTracker;
 import software.amazon.kinesis.processor.StreamTracker;
 import software.amazon.kinesis.retrieval.KinesisClientRecord;
-import software.amazon.kinesis.retrieval.RetrievalConfig;
+import software.amazon.kinesis.retrieval.RetrievalSpecificConfig;
+import software.amazon.kinesis.retrieval.fanout.FanOutConfig;
+import software.amazon.kinesis.retrieval.polling.PollingConfig;
 
 import org.springframework.context.ApplicationEventPublisher;
 import org.springframework.context.ApplicationEventPublisherAware;
@@ -131,6 +132,8 @@ public class KclMessageDrivenChannelAdapter extends MessageProducerSupport
 
 	private boolean bindSourceRecord;
 
+	private boolean fanOut = true;
+
 	private ApplicationEventPublisher applicationEventPublisher;
 
 	private volatile Scheduler scheduler;
@@ -248,6 +251,15 @@ public class KclMessageDrivenChannelAdapter extends MessageProducerSupport
 		this.bindSourceRecord = bindSourceRecord;
 	}
 
+	/**
+	 * Specify a retrieval strategy: fan-out (true; default) or polling (false).
+	 * @param fanOut false for a polling retrieval strategy.
+	 * @since 3.0.2
+	 */
+	public void setFanOut(boolean fanOut) {
+		this.fanOut = fanOut;
+	}
+
 	@Override
 	protected void onInit() {
 		super.onInit();
@@ -259,6 +271,28 @@ public class KclMessageDrivenChannelAdapter extends MessageProducerSupport
 						this.cloudWatchClient,
 						this.workerId,
 						this.recordProcessorFactory);
+
+		this.config.lifecycleConfig().taskBackoffTimeMillis(this.consumerBackoff);
+
+		RetrievalSpecificConfig retrievalSpecificConfig;
+
+		String singleStreamName = this.streams.length == 1 ? this.streams[0] : null;
+
+		if (this.fanOut) {
+			retrievalSpecificConfig =
+					new FanOutConfig(this.kinesisClient)
+							.applicationName(this.consumerGroup)
+							.streamName(singleStreamName);
+		}
+		else {
+			retrievalSpecificConfig =
+					new PollingConfig(this.kinesisClient)
+							.streamName(singleStreamName);
+		}
+
+		this.config.retrievalConfig()
+				.glueSchemaRegistryDeserializer(this.glueSchemaRegistryDeserializer)
+				.retrievalSpecificConfig(retrievalSpecificConfig);
 	}
 
 	private StreamTracker buildStreamTracker() {
@@ -281,20 +315,16 @@ public class KclMessageDrivenChannelAdapter extends MessageProducerSupport
 					+ "because it does not make sense in case of [ListenerMode.batch].");
 		}
 
-		LifecycleConfig lifecycleConfig = this.config.lifecycleConfig().taskBackoffTimeMillis(this.consumerBackoff);
-		RetrievalConfig retrievalConfig =
-				this.config.retrievalConfig()
-						.glueSchemaRegistryDeserializer(this.glueSchemaRegistryDeserializer);
 
 		this.scheduler =
 				new Scheduler(
 						this.config.checkpointConfig(),
 						this.config.coordinatorConfig(),
 						this.config.leaseManagementConfig(),
-						lifecycleConfig,
+						this.config.lifecycleConfig(),
 						this.config.metricsConfig(),
 						this.config.processorConfig(),
-						retrievalConfig);
+						this.config.retrievalConfig());
 
 		this.executor.execute(this.scheduler);
 	}