Optimize ServerRSocketConnector connection

When RSocket client connects to the server there is no reason to wrap
a `ConnectionSetupPayload` into a `Message` since we are not going to
send it downstream

* Refactor `IntegrationRSocket.handleConnectionSetupPayload()` just
return a `Mono<DataBuffer>` for converted `ConnectionSetupPayload`
* Ask for a `destination` and `RSocketRequester` from the
`IntegrationRSocket` instead of message headers

Author: artembilan

spring-integration-rsocket/src/main/java/org/springframework/integration/rsocket/IntegrationRSocket.java

@@ -110,18 +110,20 @@ class IntegrationRSocket extends AbstractRSocket {
 		this.bufferFactory = bufferFactory;
 	}
 
+	RSocketRequester getRequester() {
+		return this.requester;
+	}
+
 	/**
 	 * Wrap the {@link ConnectionSetupPayload} with a {@link Message} and
 	 * delegate to {@link #handle(Payload)} for handling.
 	 * @param payload the connection payload
 	 * @return completion handle for success or error
 	 */
-	Mono<Message<DataBuffer>> handleConnectionSetupPayload(ConnectionSetupPayload payload) {
-		String destination = getDestination(payload);
-		MessageHeaders headers = createHeaders(destination, null);
+	Mono<DataBuffer> handleConnectionSetupPayload(ConnectionSetupPayload payload) {
 		DataBuffer dataBuffer = retainDataAndReleasePayload(payload);
 		int refCount = refCount(dataBuffer);
-		return Mono.just(MessageBuilder.createMessage(dataBuffer, headers))
+		return Mono.just(dataBuffer)
 				.doFinally(s -> {
 					if (refCount(dataBuffer) == refCount) {
 						DataBufferUtils.release(dataBuffer);

spring-integration-rsocket/src/main/java/org/springframework/integration/rsocket/ServerRSocketConnector.java

@@ -29,12 +29,8 @@
 import org.springframework.context.ApplicationEventPublisherAware;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.lang.Nullable;
-import org.springframework.messaging.MessageHeaders;
-import org.springframework.messaging.handler.DestinationPatternsMessageCondition;
 import org.springframework.messaging.rsocket.RSocketRequester;
-import org.springframework.messaging.rsocket.annotation.support.RSocketRequesterMethodArgumentResolver;
 import org.springframework.util.Assert;
-import org.springframework.util.RouteMatcher;
 
 import io.rsocket.RSocketFactory;
 import io.rsocket.SocketAcceptor;
@@ -181,17 +177,10 @@ public SocketAcceptor serverAcceptor() {
 			return (setupPayload, sendingRSocket) -> {
 				IntegrationRSocket rsocket = createRSocket(setupPayload, sendingRSocket);
 				return rsocket.handleConnectionSetupPayload(setupPayload)
-						.doOnNext((message) -> {
-							MessageHeaders messageHeaders = message.getHeaders();
-							DataBuffer dataBuffer = message.getPayload();
-							String destination =
-									messageHeaders.get(DestinationPatternsMessageCondition.LOOKUP_DESTINATION_HEADER,
-											RouteMatcher.Route.class)
-											.value();
+						.doOnNext((dataBuffer) -> {
+							String destination = rsocket.getDestination(setupPayload);
 							Object rsocketRequesterKey = this.clientRSocketKeyStrategy.apply(destination, dataBuffer);
-							RSocketRequester rsocketRequester =
-									messageHeaders.get(RSocketRequesterMethodArgumentResolver.RSOCKET_REQUESTER_HEADER,
-											RSocketRequester.class);
+							RSocketRequester rsocketRequester = rsocket.getRequester();
 							this.clientRSocketRequesters.put(rsocketRequesterKey, rsocketRequester);
 							RSocketConnectedEvent rSocketConnectedEvent =
 									new RSocketConnectedEvent(rsocket, destination, dataBuffer, rsocketRequester);