Changed the way the default executor is picked; fixes gh-1212

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/async/AsyncDefaultAutoConfiguration.java

@@ -20,8 +20,13 @@ import java.util.concurrent.Executor;
 
 import brave.Tracer;
 import brave.Tracing;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 
+import org.springframework.aop.interceptor.AsyncExecutionAspectSupport;
 import org.springframework.beans.factory.BeanFactory;
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
+import org.springframework.beans.factory.NoUniqueBeanDefinitionException;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
@@ -32,6 +37,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Role;
 import org.springframework.core.task.SimpleAsyncTaskExecutor;
+import org.springframework.core.task.TaskExecutor;
 import org.springframework.scheduling.annotation.AsyncConfigurer;
 import org.springframework.scheduling.annotation.AsyncConfigurerSupport;
 
@@ -70,12 +76,71 @@ public class AsyncDefaultAutoConfiguration {
 	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
 	static class DefaultAsyncConfigurerSupport extends AsyncConfigurerSupport {
 
+		private static final Log log = LogFactory
+				.getLog(DefaultAsyncConfigurerSupport.class);
+
 		@Autowired
 		private BeanFactory beanFactory;
 
 		@Override
 		public Executor getAsyncExecutor() {
-			return new LazyTraceExecutor(this.beanFactory, new SimpleAsyncTaskExecutor());
+			Executor delegate = getDefaultExecutor();
+			return new LazyTraceExecutor(this.beanFactory, delegate);
+		}
+
+		/**
+		 * Retrieve or build a default executor for this advice instance. An executor
+		 * returned from here will be cached for further use.
+		 * <p>
+		 * The default implementation searches for a unique {@link TaskExecutor} bean in
+		 * the context, or for an {@link Executor} bean named "taskExecutor" otherwise. If
+		 * neither of the two is resolvable, this implementation will return {@code null}.
+		 * @return the default executor, or {@code null} if none available
+		 * @see AsyncExecutionAspectSupport#getDefaultExecutor(org.springframework.beans.factory.BeanFactory)
+		 */
+		private Executor getDefaultExecutor() {
+			try {
+				// Search for TaskExecutor bean... not plain Executor since that would
+				// match with ScheduledExecutorService as well, which is unusable for
+				// our purposes here. TaskExecutor is more clearly designed for it.
+				return this.beanFactory.getBean(TaskExecutor.class);
+			}
+			catch (NoUniqueBeanDefinitionException ex) {
+				log.debug("Could not find unique TaskExecutor bean", ex);
+				try {
+					return this.beanFactory.getBean(
+							AsyncExecutionAspectSupport.DEFAULT_TASK_EXECUTOR_BEAN_NAME,
+							Executor.class);
+				}
+				catch (NoSuchBeanDefinitionException ex2) {
+					if (log.isInfoEnabled()) {
+						log.info(
+								"More than one TaskExecutor bean found within the context, and none is named "
+										+ "'taskExecutor'. Mark one of them as primary or name it 'taskExecutor' (possibly "
+										+ "as an alias) in order to use it for async processing: "
+										+ ex.getBeanNamesFound());
+					}
+				}
+			}
+			catch (NoSuchBeanDefinitionException ex) {
+				log.debug("Could not find default TaskExecutor bean", ex);
+				try {
+					return this.beanFactory.getBean(
+							AsyncExecutionAspectSupport.DEFAULT_TASK_EXECUTOR_BEAN_NAME,
+							Executor.class);
+				}
+				catch (NoSuchBeanDefinitionException ex2) {
+					log.info("No task executor bean found for async processing: "
+							+ "no bean of type TaskExecutor and no bean named 'taskExecutor' either");
+				}
+				// Giving up -> either using local default executor or none at all...
+			}
+			// backward compatibility
+			if (log.isInfoEnabled()) {
+				log.info(
+						"For backward compatibility, will fallback to the default, SimpleAsyncTaskExecutor implementation");
+			}
+			return new SimpleAsyncTaskExecutor();
 		}
 
 	}

spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/async/issues/issue1212/GH1212Tests.java

@@ -0,0 +1,181 @@
+/*
+ * Copyright 2013-2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.sleuth.instrument.async.issues.issue1212;
+
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.Executor;
+
+import org.junit.Test;
+import org.slf4j.LoggerFactory;
+
+import org.springframework.aop.interceptor.AsyncExecutionAspectSupport;
+import org.springframework.boot.SpringBootConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Primary;
+import org.springframework.core.task.SimpleAsyncTaskExecutor;
+import org.springframework.core.task.TaskExecutor;
+import org.springframework.scheduling.annotation.Async;
+import org.springframework.scheduling.annotation.AsyncConfigurer;
+import org.springframework.scheduling.annotation.AsyncConfigurerSupport;
+import org.springframework.scheduling.annotation.EnableAsync;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Bertrand Renuart
+ */
+public class GH1212Tests {
+
+	@Test
+	public void defaultTaskExecutor() throws Exception {
+		try (ConfigurableApplicationContext ctx = new SpringApplicationBuilder(App.class,
+				DefaultTaskExecutorConfig.class).run()) {
+			String asyncThreadName = getAsyncThreadName(ctx);
+			assertThat(asyncThreadName).startsWith("defaultTaskExecutor");
+		}
+	}
+
+	@Test
+	public void singleTaskExecutor() throws Exception {
+		try (ConfigurableApplicationContext ctx = new SpringApplicationBuilder(App.class,
+				SingleTaskExecutorConfig.class).run()) {
+			String asyncThreadName = getAsyncThreadName(ctx);
+			assertThat(asyncThreadName).startsWith("singleTaskExecutor");
+		}
+	}
+
+	@Test
+	public void multipleTaskExecutors() throws Exception {
+		try (ConfigurableApplicationContext ctx = new SpringApplicationBuilder(App.class,
+				MultipleTaskExecutorConfig.class).run()) {
+			String asyncThreadName = getAsyncThreadName(ctx);
+			assertThat(asyncThreadName).doesNotStartWith("multipleTaskExecutor");
+			assertThat(asyncThreadName).startsWith("SimpleAsyncTaskExecutor"); // <--
+																				// comes
+																				// from
+																				// Sleuth's
+																				// own
+																				// AsyncConfigurer
+		}
+	}
+
+	@Test
+	public void customAsyncConfigurer() throws Exception {
+		try (ConfigurableApplicationContext ctx = new SpringApplicationBuilder(App.class,
+				CustomAsyncConfigurerConfig.class).run()) {
+			String asyncThreadName = getAsyncThreadName(ctx);
+			assertThat(asyncThreadName).startsWith("customAsyncConfigurer");
+		}
+	}
+
+	private String getAsyncThreadName(ApplicationContext ctx) throws Exception {
+		return ctx.getBean(AsyncComponent.class).asyncMethod().get();
+	}
+
+	@SpringBootConfiguration
+	@EnableAutoConfiguration
+	@EnableAsync
+	static class App {
+
+		@Bean
+		AsyncComponent asyncComponent() {
+			return new AsyncComponent();
+		}
+
+	}
+
+	static class AsyncComponent {
+
+		@Async
+		public CompletableFuture<String> asyncMethod() {
+			LoggerFactory.getLogger("test").info("asyncMethod invoked");
+			return CompletableFuture.completedFuture(Thread.currentThread().getName());
+		}
+
+	}
+
+	/*
+	 * Configuration with a single Executor named `taskExecutor`
+	 */
+	@Configuration
+	static class DefaultTaskExecutorConfig {
+
+		@Bean(name = AsyncExecutionAspectSupport.DEFAULT_TASK_EXECUTOR_BEAN_NAME)
+		public Executor taskExecutor() {
+			return new SimpleAsyncTaskExecutor("defaultTaskExecutor");
+		}
+
+	}
+
+	/*
+	 * Configuration with a single TaskExecutor
+	 */
+	@Configuration
+	static class SingleTaskExecutorConfig {
+
+		@Bean
+		// there's the task
+		@Primary
+		public TaskExecutor singleTaskExecutor() {
+			return new SimpleAsyncTaskExecutor("singleTaskExecutor");
+		}
+
+	}
+
+	/*
+	 * Configuration with a multiple TaskExecutors --> Spring won't pick any unless one
+	 * is @Primary
+	 */
+	@Configuration
+	static class MultipleTaskExecutorConfig {
+
+		@Bean
+		public TaskExecutor multipleTaskExecutor1() {
+			return new SimpleAsyncTaskExecutor("multipleTaskExecutor1");
+		}
+
+		@Bean
+		public TaskExecutor multipleTaskExecutor2() {
+			return new SimpleAsyncTaskExecutor("multipleTaskExecutor2");
+		}
+
+	}
+
+	/*
+	 * Configuration where a custom AsyncConfigurer is provided
+	 */
+	@Configuration
+	static class CustomAsyncConfigurerConfig {
+
+		@Bean
+		public AsyncConfigurer customAsyncConfigurer() {
+			return new AsyncConfigurerSupport() {
+				@Override
+				public Executor getAsyncExecutor() {
+					return new SimpleAsyncTaskExecutor("customAsyncConfigurer");
+				}
+			};
+		}
+
+	}
+
+}