Simplify ReactorNettyTcpClient input

Create a ReactorNettyCodec to hold the decoding and encoding function
and consumer along with a package-private sub-class that delegates to
StompDecoder and StompEncoder.

Issue: SPR-14531

Author: rstoyanchev

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/ReactorNettyTcpStompClient.java

@@ -16,16 +16,9 @@
 
 package org.springframework.messaging.simp.stomp;
 
-import java.util.List;
-import java.util.function.BiConsumer;
-import java.util.function.Function;
-
-import io.netty.buffer.ByteBuf;
-import reactor.core.scheduler.Schedulers;
-
-import org.springframework.messaging.Message;
 import org.springframework.messaging.tcp.TcpOperations;
 import org.springframework.messaging.tcp.reactor.ReactorNettyTcpClient;
+import org.springframework.util.Assert;
 import org.springframework.util.concurrent.ListenableFuture;
 
 /**
@@ -38,28 +31,29 @@ public class ReactorNettyTcpStompClient extends StompClientSupport {
 
 	private final TcpOperations<byte[]> tcpClient;
 
+
 	/**
 	 * Create an instance with host "127.0.0.1" and port 61613.
 	 */
 	public ReactorNettyTcpStompClient() {
 		this("127.0.0.1", 61613);
 	}
 
-
 	/**
 	 * Create an instance with the given host and port.
 	 * @param host the host
 	 * @param port the port
 	 */
-	public ReactorNettyTcpStompClient(final String host, final int port) {
-		this.tcpClient = create(host, port, new StompDecoder());
+	public ReactorNettyTcpStompClient(String host, int port) {
+		this.tcpClient = new ReactorNettyTcpClient<byte[]>(host, port, new StompReactorNettyCodec());
 	}
 
 	/**
 	 * Create an instance with a pre-configured TCP client.
 	 * @param tcpClient the client to use
 	 */
 	public ReactorNettyTcpStompClient(TcpOperations<byte[]> tcpClient) {
+		Assert.notNull(tcpClient, "'tcpClient' is required");
 		this.tcpClient = tcpClient;
 	}
 
@@ -94,49 +88,4 @@ public void shutdown() {
 		this.tcpClient.shutdown();
 	}
 
-	/**
-	 * Create a new {@link ReactorNettyTcpClient} with Stomp specific configuration for
-	 * encoding, decoding and hand-off.
-	 *
-	 * @param host target host
-	 * @param port target port
-	 * @param decoder {@link StompDecoder} to use
-	 * @return a new {@link TcpOperations}
-	 */
-	protected static TcpOperations<byte[]> create(String host, int port, StompDecoder decoder) {
-		return new ReactorNettyTcpClient<>(host, port,
-				new ReactorNettyTcpClient.MessageHandlerConfiguration<>(
-						new DecodingFunction(decoder),
-						new EncodingConsumer(new StompEncoder()),
-						128,
-						Schedulers.newParallel("StompClient")));
-	}
-
-	private static final class EncodingConsumer implements BiConsumer<ByteBuf, Message<byte[]>> {
-
-		private final StompEncoder encoder;
-
-		public EncodingConsumer(StompEncoder encoder) {
-			this.encoder = encoder;
-		}
-
-		@Override
-		public void accept(ByteBuf byteBuf, Message<byte[]> message) {
-			byteBuf.writeBytes(this.encoder.encode(message));
-		}
-	}
-
-	private static final class DecodingFunction implements Function<ByteBuf, List<Message<byte[]>>> {
-
-		private final StompDecoder decoder;
-
-		public DecodingFunction(StompDecoder decoder) {
-			this.decoder = decoder;
-		}
-
-		@Override
-		public List<Message<byte[]>> apply(ByteBuf buffer) {
-			return this.decoder.decode(buffer.nioBuffer());
-		}
-	}
 }

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompBrokerRelayMessageHandler.java

@@ -40,6 +40,7 @@
 import org.springframework.messaging.tcp.TcpConnection;
 import org.springframework.messaging.tcp.TcpConnectionHandler;
 import org.springframework.messaging.tcp.TcpOperations;
+import org.springframework.messaging.tcp.reactor.ReactorNettyCodec;
 import org.springframework.messaging.tcp.reactor.ReactorNettyTcpClient;
 import org.springframework.util.Assert;
 import org.springframework.util.concurrent.ListenableFuture;
@@ -387,8 +388,8 @@ protected void startInternal() {
 		if (this.tcpClient == null) {
 			StompDecoder decoder = new StompDecoder();
 			decoder.setHeaderInitializer(getHeaderInitializer());
-
-			this.tcpClient = ReactorNettyTcpStompClient.create(this.relayHost, this.relayPort, decoder);
+			ReactorNettyCodec<byte[]> codec = new StompReactorNettyCodec(decoder);
+			this.tcpClient = new ReactorNettyTcpClient<>(this.relayHost, this.relayPort, codec);
 		}
 
 		if (logger.isInfoEnabled()) {

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompReactorNettyCodec.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2002-2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.messaging.simp.stomp;
+
+import org.springframework.messaging.tcp.reactor.ReactorNettyCodec;
+
+/**
+ * {@code ReactorNettyCodec} that delegates to {@link StompDecoder} and
+ * {@link StompEncoder}.
+ *
+ * @author Rossen Stoyanchev
+ * @since 5.0
+ */
+class StompReactorNettyCodec extends ReactorNettyCodec<byte[]> {
+
+	public StompReactorNettyCodec() {
+		this(new StompDecoder(), new StompEncoder());
+	}
+
+	public StompReactorNettyCodec(StompDecoder decoder) {
+		this(decoder, new StompEncoder());
+	}
+
+	public StompReactorNettyCodec(StompDecoder decoder, StompEncoder encoder) {
+		super(byteBuf -> decoder.decode(byteBuf.nioBuffer()),
+				(byteBuf, message) -> byteBuf.writeBytes(encoder.encode(message)));
+	}
+
+}

spring-messaging/src/main/java/org/springframework/messaging/tcp/reactor/ReactorNettyCodec.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2002-2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.messaging.tcp.reactor;
+
+import java.util.Collection;
+import java.util.function.BiConsumer;
+import java.util.function.Function;
+
+import io.netty.buffer.ByteBuf;
+
+import org.springframework.messaging.Message;
+import org.springframework.util.Assert;
+
+/**
+ * Simple holder for a decoding {@link Function} and an encoding
+ * {@link BiConsumer} to use with Reactor Netty.
+ *
+ * @author Rossen Stoyanchev
+ * @since 5.0
+ */
+public class ReactorNettyCodec<P> {
+
+	private final Function<? super ByteBuf, ? extends Collection<Message<P>>> decoder;
+
+	private final BiConsumer<? super ByteBuf, ? super Message<P>> encoder;
+
+
+	public ReactorNettyCodec(Function<? super ByteBuf, ? extends Collection<Message<P>>> decoder,
+			BiConsumer<? super ByteBuf, ? super Message<P>> encoder) {
+
+		Assert.notNull(decoder, "'decoder' is required");
+		Assert.notNull(encoder, "'encoder' is required");
+		this.decoder = decoder;
+		this.encoder = encoder;
+	}
+
+	public Function<? super ByteBuf, ? extends Collection<Message<P>>> getDecoder() {
+		return this.decoder;
+	}
+
+	public BiConsumer<? super ByteBuf, ? super Message<P>> getEncoder() {
+		return this.encoder;
+	}
+
+}