From 71ee26b0a1264329fb8a63c4b9df38c9bc0c041f Mon Sep 17 00:00:00 2001
From: Chris Bono <chris.bono@gmail.com>
Date: Wed, 17 Aug 2022 00:07:29 -0500
Subject: [PATCH] Use empty context for AOT binder child context

Previously, when running in AOT mode the binder child context
was created w/ the same beans as when in JVM mode. The whole
point of the former is to static initialize an empty fresh context
using the AOT generated initializer.
---
 .../binder/BinderChildContextInitializer.java |  2 +-
 .../stream/binder/DefaultBinderFactory.java   | 47 +++++++++++++++++--
 2 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/core/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/binder/BinderChildContextInitializer.java b/core/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/binder/BinderChildContextInitializer.java
index 93c89d9f1..29a9ba46a 100644
--- a/core/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/binder/BinderChildContextInitializer.java
+++ b/core/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/binder/BinderChildContextInitializer.java
@@ -153,7 +153,7 @@ public class BinderChildContextInitializer implements ApplicationContextAware, B
 							this.logger.debug(() -> "Generating AOT child context initializer for " + name);
 							GenerationContext childGenerationContext = generationContext.withName(name + "Binder");
 							ClassName initializerClassName = aotGenerator.processAheadOfTime(context, childGenerationContext);
-							method.addStatement("$T<? extends $T>" + name + "Initializer = new $L()", ApplicationContextInitializer.class,
+							method.addStatement("$T<? extends $T> " + name + "Initializer = new $L()", ApplicationContextInitializer.class,
 									ConfigurableApplicationContext.class, initializerClassName);
 							method.addStatement("initializers.put($S," + name + "Initializer)", name);
 						});
diff --git a/core/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/binder/DefaultBinderFactory.java b/core/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/binder/DefaultBinderFactory.java
index 0c7a20336..f18d11d89 100644
--- a/core/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/binder/DefaultBinderFactory.java
+++ b/core/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/binder/DefaultBinderFactory.java
@@ -265,9 +265,7 @@ public class DefaultBinderFactory implements BinderFactory, DisposableBean, Appl
 			ConfigurableApplicationContext binderProducingContext;
 			if (this.binderChildContextInitializers.containsKey(configurationName)) {
 				this.logger.info("Using AOT pre-prepared initializer to construct binder child context for " + configurationName);
-				binderProducingContext = this.initializeBinderContextSimple(configurationName, binderProperties,
-						binderType, binderConfiguration, false);
-				GenericApplicationContext c = null;
+				binderProducingContext = this.createUnitializedContextForAOT(configurationName, binderProperties, binderConfiguration);
 				this.binderChildContextInitializers.get(configurationName).initialize(binderProducingContext);
 				binderProducingContext.refresh();
 			}
@@ -447,6 +445,49 @@ public class DefaultBinderFactory implements BinderFactory, DisposableBean, Appl
 		return binderProducingContext;
 	}
 
+	/**
+	 * Creates a bare minimum application context that can be initialized by AOT.
+	 *
+	 * @param configurationName binder configuration name
+	 * @param binderProperties binder properties
+	 * @param binderConfiguration binder configuration
+	 * @return a binder child application context suitable for AOT initialization
+	 */
+	GenericApplicationContext createUnitializedContextForAOT(String configurationName,
+			Map<String, Object> binderProperties, BinderConfiguration binderConfiguration) {
+
+		GenericApplicationContext binderContext = new GenericApplicationContext();
+
+		MapPropertySource binderPropertySource = new MapPropertySource(configurationName, binderProperties);
+		binderContext.getEnvironment().getPropertySources().addFirst(binderPropertySource);
+		binderContext.setDisplayName(configurationName + "_context");
+		boolean useApplicationContextAsParent = binderProperties.isEmpty() && this.context != null;
+		ConfigurableEnvironment environment = this.context != null ? this.context.getEnvironment() : null;
+		if (useApplicationContextAsParent) {
+			binderContext.setParent(this.context);
+		}
+		else if (this.context != null) {
+			binderContext.addApplicationListener(event -> {
+				if (context != null) {
+					try {
+						context.publishEvent(event);
+					}
+					catch (Exception e) {
+						logger.warn("Failed to publish " + event, e);
+					}
+				}
+			});
+			if (environment != null && (useApplicationContextAsParent || binderConfiguration.isInheritEnvironment())) {
+				binderContext.getEnvironment().merge(environment);
+				binderContext.getEnvironment().getPropertySources().remove("configurationProperties");
+				binderContext.getEnvironment().getPropertySources()
+						.addFirst(new MapPropertySource("defaultBinderFactoryProperties",
+								Collections.singletonMap("spring.main.web-application-type", "NONE")));
+			}
+		}
+		return binderContext;
+	}
+
 	/**
 	 * Ensures that nested properties are flattened (i.e., foo.bar=baz instead of
 	 * foo={bar=baz}).