Improve TCP connection info logging.

After the recent changes to expose configuring TcpOperations, it no
longer makes sense to automatically log the relayHost/Port since that's
mutually exclusive with a custom TcpOperations.

Instead we delegate to TcpOperations.toString().

Issue: SPR-16801

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

@@ -89,4 +89,8 @@ public class ReactorNettyTcpStompClient extends StompClientSupport {
 		this.tcpClient.shutdown();
 	}
 
+	@Override
+	public String toString() {
+		return "ReactorNettyTcpStompClient[" + this.tcpClient + "]";
+	}
 }

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

@@ -82,12 +82,12 @@ public class StompBrokerRelayMessageHandler extends AbstractBrokerMessageHandler
 
 	public static final String SYSTEM_SESSION_ID = "_system_";
 
-	// STOMP recommends error of margin for receiving heartbeats
+	/** STOMP recommended error of margin for receiving heartbeats */
 	private static final long HEARTBEAT_MULTIPLIER = 3;
 
 	/**
-	 * A heartbeat is setup once a CONNECTED frame is received which contains the heartbeat settings
-	 * we need. If we don't receive CONNECTED within a minute, the connection is closed proactively.
+	 * Heartbeat starts once CONNECTED frame with heartbeat settings is received.
+	 * If CONNECTED doesn't arrive within a minute, we'll close the connection.
 	 */
 	private static final int MAX_TIME_TO_CONNECTED_FRAME = 60 * 1000;
 
@@ -403,7 +403,7 @@ public class StompBrokerRelayMessageHandler extends AbstractBrokerMessageHandler
 		}
 
 		if (logger.isInfoEnabled()) {
-			logger.info("Connecting \"system\" session to " + this.relayHost + ":" + this.relayPort);
+			logger.info("Starting \"system\" session, " + toString());
 		}
 
 		StompHeaderAccessor accessor = StompHeaderAccessor.create(StompCommand.CONNECT);
@@ -552,7 +552,11 @@ public class StompBrokerRelayMessageHandler extends AbstractBrokerMessageHandler
 
 	@Override
 	public String toString() {
-		return "StompBrokerRelay[" + this.relayHost + ":" + this.relayPort + "]";
+		return "StompBrokerRelay[" + getTcpClientInfo() + "]";
+	}
+
+	private String getTcpClientInfo() {
+		return this.tcpClient != null ? this.tcpClient.toString() : this.relayHost + ":" + this.relayPort;
 	}
 
 
@@ -987,7 +991,7 @@ public class StompBrokerRelayMessageHandler extends AbstractBrokerMessageHandler
 	private static class VoidCallable implements Callable<Void> {
 
 		@Override
-		public Void call() throws Exception {
+		public Void call() {
 			return null;
 		}
 	}
@@ -1014,7 +1018,7 @@ public class StompBrokerRelayMessageHandler extends AbstractBrokerMessageHandler
 		}
 
 		public String toString() {
-			return (connectionHandlers.size() + " sessions, " + relayHost + ":" + relayPort +
+			return (connectionHandlers.size() + " sessions, " + getTcpClientInfo() +
 					(isBrokerAvailable() ? " (available)" : " (not available)") +
 					", processed CONNECT(" + this.connect.get() + ")-CONNECTED(" +
 					this.connected.get() + ")-DISCONNECT(" + this.disconnect.get() + ")");

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -30,6 +30,8 @@ import io.netty.channel.group.ChannelGroup;
 import io.netty.channel.group.DefaultChannelGroup;
 import io.netty.handler.codec.ByteToMessageDecoder;
 import io.netty.util.concurrent.ImmediateEventExecutor;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.DirectProcessor;
 import reactor.core.publisher.Flux;
@@ -65,6 +67,8 @@ import org.springframework.util.concurrent.SettableListenableFuture;
  */
 public class ReactorNettyTcpClient<P> implements TcpOperations<P> {
 
+	private static Log logger = LogFactory.getLog(ReactorNettyTcpClient.class);
+
 	private static final int PUBLISH_ON_BUFFER_SIZE = 16;
 
 
@@ -201,7 +205,7 @@ public class ReactorNettyTcpClient<P> implements TcpOperations<P> {
 				.doOnNext(updateConnectMono(connectMono))
 				.doOnError(updateConnectMono(connectMono))
 				.doOnError(handler::afterConnectFailure)    // report all connect failures to the handler
-				.flatMap(NettyContext::onClose)                // post-connect issues
+				.flatMap(NettyContext::onClose)             // post-connect issues
 				.retryWhen(reconnectFunction(strategy))
 				.repeatWhen(reconnectFunction(strategy))
 				.subscribe();
@@ -281,6 +285,11 @@ public class ReactorNettyTcpClient<P> implements TcpOperations<P> {
 		});
 	}
 
+	@Override
+	public String toString() {
+		return "ReactorNettyTcpClient[" + this.tcpClient + "]";
+	}
+
 
 	private class ReactorNettyHandler implements BiFunction<NettyInbound, NettyOutbound, Publisher<Void>> {
 
@@ -293,6 +302,9 @@ public class ReactorNettyTcpClient<P> implements TcpOperations<P> {
 		@Override
 		@SuppressWarnings("unchecked")
 		public Publisher<Void> apply(NettyInbound inbound, NettyOutbound outbound) {
+			if (logger.isDebugEnabled()) {
+				logger.debug("Connected to " + inbound.remoteAddress());
+			}
 			DirectProcessor<Void> completion = DirectProcessor.create();
 			TcpConnection<P> connection = new ReactorNettyTcpConnection<>(inbound, outbound,  codec, completion);
 			scheduler.schedule(() -> connectionHandler.afterConnected(connection));
@@ -321,7 +333,7 @@ public class ReactorNettyTcpClient<P> implements TcpOperations<P> {
 		}
 
 		@Override
-		protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
+		protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) {
 			Collection<Message<P>> messages = codec.decode(in);
 			out.addAll(messages);
 		}