GH-1225: Fix Log4j2 Appender Termination

Replaces #1225

`manager.stop()` was never called to destroy the connection factory, preventing
JVM exit.

Also protect for re-connecting after stop (both appenders).

Tested with a Spring Boot application.

**cherry-pick to 2.2.x, 2.1.x, 1.7.x**

Author: garyrussell

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/log4j2/AmqpAppender.java

@@ -53,6 +53,7 @@
 import org.apache.logging.log4j.core.layout.PatternLayout;
 import org.apache.logging.log4j.core.util.Integers;
 
+import org.springframework.amqp.AmqpApplicationContextClosedException;
 import org.springframework.amqp.AmqpException;
 import org.springframework.amqp.core.DirectExchange;
 import org.springframework.amqp.core.Exchange;
@@ -72,6 +73,9 @@
 import org.springframework.amqp.rabbit.core.RabbitTemplate;
 import org.springframework.amqp.rabbit.support.RabbitExceptionTranslator;
 import org.springframework.amqp.utils.JavaUtils;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.event.ContextClosedEvent;
+import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
 import org.springframework.retry.RetryPolicy;
@@ -354,6 +358,9 @@ protected void doSend(Event event, LogEvent logEvent, MessageProperties amqpProp
 			message = postProcessMessageBeforeSend(message, event);
 			this.rabbitTemplate.send(this.manager.exchangeName, routingKey, message);
 		}
+		catch (AmqpApplicationContextClosedException e) {
+			getHandler().error("Could not send log message " + logEvent.getMessage() + " appender is stopped");
+		}
 		catch (AmqpException e) {
 			int retries = event.incrementRetries();
 			if (this.manager.async && retries < this.manager.maxSenderRetries) {
@@ -380,7 +387,7 @@ public void run() {
 	@Override
 	protected boolean stop(long timeout, TimeUnit timeUnit, boolean changeLifeCycleState) {
 		boolean stopped = super.stop(timeout, timeUnit, changeLifeCycleState);
-		return stopped || this.manager.stop(timeout, timeUnit);
+		return this.manager.stop(timeout, timeUnit) || stopped;
 	}
 
 	/**
@@ -449,6 +456,8 @@ protected static class AmqpManager extends AbstractManager {
 
 		private static final int DEFAULT_MAX_SENDER_RETRIES = 30;
 
+		private final ApplicationContext context = new GenericApplicationContext();
+
 		/**
 		 * True to send events on separate threads.
 		 */
@@ -656,6 +665,7 @@ private boolean activateOptions() {
 						.withNoConsoleNoAnsi(true)
 						.build();
 				this.connectionFactory = new CachingConnectionFactory(rabbitConnectionFactory);
+				this.connectionFactory.setApplicationContext(this.context);
 				if (StringUtils.hasText(this.connectionName)) {
 					this.connectionFactory.setConnectionNameStrategy(cf -> this.connectionName);
 				}
@@ -745,6 +755,7 @@ protected boolean releaseSub(long timeout, TimeUnit timeUnit) {
 			this.retryTimer.cancel();
 			this.senderPool.shutdownNow();
 			this.connectionFactory.destroy();
+			this.connectionFactory.onApplicationEvent(new ContextClosedEvent(this.context));
 			try {
 				return this.senderPool.awaitTermination(timeout, timeUnit);
 			}

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/logback/AmqpAppender.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2019 the original author or authors.
+ * Copyright 2014-2020 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.
@@ -32,6 +32,7 @@
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
 
+import org.springframework.amqp.AmqpApplicationContextClosedException;
 import org.springframework.amqp.AmqpException;
 import org.springframework.amqp.core.DirectExchange;
 import org.springframework.amqp.core.Exchange;
@@ -51,6 +52,9 @@
 import org.springframework.amqp.rabbit.core.RabbitTemplate;
 import org.springframework.amqp.rabbit.support.RabbitExceptionTranslator;
 import org.springframework.amqp.utils.JavaUtils;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.event.ContextClosedEvent;
+import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
 import org.springframework.util.StringUtils;
@@ -120,6 +124,8 @@ public class AmqpAppender extends AppenderBase<ILoggingEvent> {
 	 */
 	public static final String THREAD_NAME = "thread";
 
+	private final ApplicationContext context = new GenericApplicationContext();
+
 	/**
 	 * Name of the exchange to publish log events to.
 	 */
@@ -682,6 +688,7 @@ public void start() {
 			this.locationLayout.setContext(getContext());
 			this.locationLayout.start();
 			this.connectionFactory = new CachingConnectionFactory(rabbitConnectionFactory);
+			this.connectionFactory.setApplicationContext(this.context);
 			if (StringUtils.hasText(this.connectionName)) {
 				this.connectionFactory.setConnectionNameStrategy(cf -> this.connectionName);
 			}
@@ -797,6 +804,7 @@ public void stop() {
 		}
 		if (null != this.connectionFactory) {
 			this.connectionFactory.destroy();
+			this.connectionFactory.onApplicationEvent(new ContextClosedEvent(this.context));
 		}
 		this.retryTimer.cancel();
 		this.routingKeyLayout.stop();
@@ -956,6 +964,9 @@ private void doSend(RabbitTemplate rabbitTemplate, final Event event, ILoggingEv
 				message = postProcessMessageBeforeSend(message, event);
 				rabbitTemplate.send(AmqpAppender.this.exchangeName, routingKey, message);
 			}
+			catch (AmqpApplicationContextClosedException e) {
+				addError("Could not send log message " + logEvent.getMessage() + " appender is stopped");
+			}
 			catch (AmqpException e) {
 				int retries = event.incrementRetries();
 				if (retries < AmqpAppender.this.maxSenderRetries) {