From 146576d3686baf35502fc0ac047017f7619482f2 Mon Sep 17 00:00:00 2001
From: Oleg Zhurakousky <ozhurakousky@pivotal.io>
Date: Wed, 13 Jun 2018 14:25:01 -0400
Subject: [PATCH] GH-1385 Enhance bean registration error

Enhanced bean registration error message in the event  multiple bindings point to the same destination
Resolves #1385
Resolves #1390
---
 .../binder/AbstractMessageChannelBinder.java  | 24 ++++++++++++++-----
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/binder/AbstractMessageChannelBinder.java b/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/binder/AbstractMessageChannelBinder.java
index a98c70318..930a3da67 100644
--- a/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/binder/AbstractMessageChannelBinder.java
+++ b/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/binder/AbstractMessageChannelBinder.java
@@ -444,7 +444,7 @@ public abstract class AbstractMessageChannelBinder<C extends ConsumerProperties,
 		}
 		else {
 			errorChannel = new PublishSubscribeChannel();
-			beanFactory.registerSingleton(errorChannelName, errorChannel);
+			this.registerComponentWithBeanFactory(errorChannelName, errorChannel);
 			errorChannel = (PublishSubscribeChannel) beanFactory.initializeBean(errorChannel, errorChannelName);
 		}
 		MessageChannel defaultErrorChannel = null;
@@ -457,7 +457,7 @@ public abstract class AbstractMessageChannelBinder<C extends ConsumerProperties,
 			errorBridge.setOutputChannel(defaultErrorChannel);
 			errorChannel.subscribe(errorBridge);
 			String errorBridgeHandlerName = getErrorBridgeName(destination);
-			beanFactory.registerSingleton(errorBridgeHandlerName, errorBridge);
+			this.registerComponentWithBeanFactory(errorBridgeHandlerName, errorBridge);
 			beanFactory.initializeBean(errorBridge, errorBridgeHandlerName);
 		}
 		return errorChannel;
@@ -505,7 +505,7 @@ public abstract class AbstractMessageChannelBinder<C extends ConsumerProperties,
 		}
 		else {
 			errorChannel = new BinderErrorChannel();
-			beanFactory.registerSingleton(errorChannelName, errorChannel);
+			this.registerComponentWithBeanFactory(errorChannelName, errorChannel);
 			errorChannel = (LastSubscriberAwareChannel) beanFactory.initializeBean(errorChannel, errorChannelName);
 		}
 		ErrorMessageSendingRecoverer recoverer;
@@ -516,7 +516,7 @@ public abstract class AbstractMessageChannelBinder<C extends ConsumerProperties,
 			recoverer = new ErrorMessageSendingRecoverer(errorChannel, errorMessageStrategy);
 		}
 		String recovererBeanName = getErrorRecovererName(destination, group, consumerProperties);
-		beanFactory.registerSingleton(recovererBeanName, recoverer);
+		this.registerComponentWithBeanFactory(recovererBeanName, recoverer);
 		beanFactory.initializeBean(recoverer, recovererBeanName);
 		MessageHandler handler;
 		if (polled) {
@@ -535,7 +535,7 @@ public abstract class AbstractMessageChannelBinder<C extends ConsumerProperties,
 		}
 		String errorMessageHandlerName = getErrorMessageHandlerName(destination, group, consumerProperties);
 		if (handler != null) {
-			beanFactory.registerSingleton(errorMessageHandlerName, handler);
+			this.registerComponentWithBeanFactory(errorMessageHandlerName, handler);
 			beanFactory.initializeBean(handler, errorMessageHandlerName);
 			errorChannel.subscribe(handler);
 		}
@@ -544,7 +544,7 @@ public abstract class AbstractMessageChannelBinder<C extends ConsumerProperties,
 			errorBridge.setOutputChannel(defaultErrorChannel);
 			errorChannel.subscribe(errorBridge);
 			String errorBridgeHandlerName = getErrorBridgeName(destination, group, consumerProperties);
-			beanFactory.registerSingleton(errorBridgeHandlerName, errorBridge);
+			this.registerComponentWithBeanFactory(errorBridgeHandlerName, errorBridge);
 			beanFactory.initializeBean(errorBridge, errorBridgeHandlerName);
 		}
 		return new ErrorInfrastructure(errorChannel, recoverer, handler);
@@ -698,6 +698,18 @@ public abstract class AbstractMessageChannelBinder<C extends ConsumerProperties,
 		}
 	}
 
+	private void registerComponentWithBeanFactory(String name, Object component) {
+		if (getApplicationContext().getBeanFactory().containsBean(name)) {
+			throw new IllegalStateException("Failed to register bean with name '" + name + "', since bean with the same name already exists. Possible reason: "
+					+ "You may have multiple bindings with the same 'destination' and 'group' name (consumer side) "
+					+ "and multiple bindings with the same 'destination' name (producer side). Solution: ensure each binding uses different group name (consumer side) "
+					+ "or 'destination' name (producer side)." );
+		}
+		else {
+			getApplicationContext().getBeanFactory().registerSingleton(name, component);
+		}
+	}
+
 	private final class SendingHandler extends AbstractMessageHandler implements Lifecycle {
 
 		private final boolean embedHeaders;