Throw the target exception instead of InvocationTargetException (#1093)

Fixes gh-1092

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

@@ -16,6 +16,7 @@
 
 package org.springframework.cloud.sleuth.instrument.async;
 
+import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.util.concurrent.Executor;
@@ -38,6 +39,8 @@ import org.springframework.util.ReflectionUtils;
  * method or is final.
  *
  * @author Marcin Grzejszczak
+ * @author Jesus Alonso
+ * @author Denys Ivano
  * @since 1.1.4
  */
 class ExecutorBeanPostProcessor implements BeanPostProcessor {
@@ -124,7 +127,13 @@ class ExecutorMethodInterceptor<T extends Executor> implements MethodInterceptor
 		Executor executor = executor(this.beanFactory, this.delegate);
 		Method methodOnTracedBean = getMethod(invocation, executor);
 		if (methodOnTracedBean != null) {
-			return methodOnTracedBean.invoke(executor, invocation.getArguments());
+			try {
+				return methodOnTracedBean.invoke(executor, invocation.getArguments());
+			} catch (InvocationTargetException ex) {
+				// gh-1092: throw the target exception (if present)
+				Throwable cause = ex.getCause();
+				throw (cause != null) ? cause : ex;
+			}
 		}
 		return invocation.proceed();
 	}

spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/async/ExecutorBeanPostProcessorTests.java

@@ -18,14 +18,20 @@ package org.springframework.cloud.sleuth.instrument.async;
 
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
+import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.ScheduledExecutorService;
 
+import brave.Tracing;
+import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.Mock;
+import org.mockito.Mockito;
 import org.mockito.junit.MockitoJUnitRunner;
 import org.springframework.aop.framework.AopConfigException;
 import org.springframework.beans.factory.BeanFactory;
+import org.springframework.cloud.sleuth.DefaultSpanNamer;
+import org.springframework.cloud.sleuth.SpanNamer;
 import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
 import org.springframework.util.ClassUtils;
 
@@ -34,6 +40,7 @@ import static org.assertj.core.api.BDDAssertions.thenThrownBy;
 
 /**
  * @author Marcin Grzejszczak
+ * @author Denys Ivano
  */
 @RunWith(MockitoJUnitRunner.class)
 public class ExecutorBeanPostProcessorTests {
@@ -110,4 +117,28 @@ public class ExecutorBeanPostProcessorTests {
 				.hasMessage("foo");
 	}
 
+	@Test
+	public void should_throw_real_exception_when_using_proxy() throws Exception {
+		// for LazyTraceExecutor
+		Mockito.when(this.beanFactory.getBean(Tracing.class))
+			.thenReturn(Tracing.newBuilder().build());
+		Mockito.when(this.beanFactory.getBean(SpanNamer.class))
+			.thenReturn(new DefaultSpanNamer());
+
+		Object o = new ExecutorBeanPostProcessor(this.beanFactory)
+			.postProcessAfterInitialization(new RejectedExecutionExecutor(), "fooExecutor");
+
+		then(o).isInstanceOf(RejectedExecutionExecutor.class);
+		then(ClassUtils.isCglibProxy(o)).isTrue();
+		thenThrownBy(() -> ((RejectedExecutionExecutor) o).execute(() -> {}))
+			.isInstanceOf(RejectedExecutionException.class)
+			.hasMessage("rejected");
+	}
+
+	class RejectedExecutionExecutor implements Executor {
+		@Override public void execute(Runnable task) {
+			throw new RejectedExecutionException("rejected");
+		}
+	}
+
 }