Allow @async qualifier to be declared with a placeholder or SpEL expression

Closes gh-27818

Author: terminux

spring-aop/src/main/java/org/springframework/aop/interceptor/AsyncExecutionAspectSupport.java

@@ -34,13 +34,16 @@
 import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.beans.factory.NoUniqueBeanDefinitionException;
 import org.springframework.beans.factory.annotation.BeanFactoryAnnotationUtils;
+import org.springframework.beans.factory.config.ConfigurableBeanFactory;
+import org.springframework.beans.factory.config.EmbeddedValueResolver;
 import org.springframework.core.task.AsyncListenableTaskExecutor;
 import org.springframework.core.task.AsyncTaskExecutor;
 import org.springframework.core.task.TaskExecutor;
 import org.springframework.core.task.support.TaskExecutorAdapter;
 import org.springframework.lang.Nullable;
 import org.springframework.util.ReflectionUtils;
 import org.springframework.util.StringUtils;
+import org.springframework.util.StringValueResolver;
 import org.springframework.util.concurrent.ListenableFuture;
 import org.springframework.util.function.SingletonSupplier;
 
@@ -208,6 +211,11 @@ protected Executor findQualifiedExecutor(@Nullable BeanFactory beanFactory, Stri
 			throw new IllegalStateException("BeanFactory must be set on " + getClass().getSimpleName() +
 					" to access qualified executor '" + qualifier + "'");
 		}
+		if (beanFactory instanceof ConfigurableBeanFactory configurableBeanFactory) {
+			StringValueResolver embeddedValueResolver = new EmbeddedValueResolver(configurableBeanFactory);
+			String resolvedValue = embeddedValueResolver.resolveStringValue(qualifier);
+			qualifier = resolvedValue != null ? resolvedValue : "";
+		}
 		return BeanFactoryAnnotationUtils.qualifiedBeanOfType(beanFactory, Executor.class, qualifier);
 	}
 

spring-context/src/main/java/org/springframework/scheduling/annotation/Async.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -57,6 +57,8 @@
 
 	/**
 	 * A qualifier value for the specified asynchronous operation(s).
+	 * <p>The value support expression such as <code>#{systemProperties.myExecutor}</code>
+	 * or property placeholder such as <code>${my.app.myExecutor}</code>.
 	 * <p>May be used to determine the target executor to be used when executing
 	 * the asynchronous operation(s), matching the qualifier value (or the bean
 	 * name) of a specific {@link java.util.concurrent.Executor Executor} or

spring-context/src/test/java/org/springframework/scheduling/annotation/EnableAsyncTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -21,6 +21,7 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 import java.lang.reflect.Method;
+import java.util.Properties;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
@@ -47,6 +48,7 @@
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.context.annotation.Lazy;
+import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
 import org.springframework.core.Ordered;
 import org.springframework.lang.Nullable;
 import org.springframework.scheduling.concurrent.CustomizableThreadFactory;
@@ -130,6 +132,29 @@ public void withAsyncBeanWithExecutorQualifiedByName() throws ExecutionException
 		ctx.close();
 	}
 
+	@Test
+	public void withAsyncBeanWithExecutorQualifiedByExpression() throws ExecutionException, InterruptedException {
+		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+		System.getProperties().put("myExecutor", "myExecutor1");
+		PropertySourcesPlaceholderConfigurer placeholderConfigurer = new PropertySourcesPlaceholderConfigurer();
+		placeholderConfigurer.setProperties(new Properties() {{
+			put("my.app.myExecutor", "myExecutor2");
+		}});
+		placeholderConfigurer.postProcessBeanFactory(context.getBeanFactory());
+
+		context.register(AsyncWithExecutorQualifiedByExpressionConfig.class);
+		context.refresh();
+
+		AsyncBeanWithExecutorQualifiedByExpression asyncBean = context.getBean(AsyncBeanWithExecutorQualifiedByExpression.class);
+		Future<Thread> workerThread1 = asyncBean.myWork1();
+		assertThat(workerThread1.get().getName()).doesNotStartWith("myExecutor2-").startsWith("myExecutor1-");
+
+		Future<Thread> workerThread2 = asyncBean.myWork2();
+		assertThat(workerThread2.get().getName()).startsWith("myExecutor2-");
+
+		context.close();
+	}
+
 	@Test
 	public void asyncProcessorIsOrderedLowestPrecedenceByDefault() {
 		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
@@ -346,6 +371,19 @@ public Future<Thread> work3() {
 		}
 	}
 
+	static class AsyncBeanWithExecutorQualifiedByExpression {
+
+		@Async("#{systemProperties.myExecutor}")
+		public Future<Thread> myWork1() {
+			return new AsyncResult<>(Thread.currentThread());
+		}
+
+		@Async("${my.app.myExecutor}")
+		public Future<Thread> myWork2() {
+			return new AsyncResult<>(Thread.currentThread());
+		}
+	}
+
 
 	static class AsyncBean {
 
@@ -475,6 +513,27 @@ public Executor otherExecutor() {
 		}
 	}
 
+	@Configuration
+	@EnableAsync
+	static class AsyncWithExecutorQualifiedByExpressionConfig {
+
+		@Bean
+		public AsyncBeanWithExecutorQualifiedByExpression asyncBean() {
+			return new AsyncBeanWithExecutorQualifiedByExpression();
+		}
+
+		@Bean
+		public Executor myExecutor1() {
+			return new ThreadPoolTaskExecutor();
+		}
+
+		@Bean
+		@Qualifier("myExecutor")
+		public Executor myExecutor2() {
+			return new ThreadPoolTaskExecutor();
+		}
+	}
+
 
 	@Configuration
 	@EnableAsync