From dbf57a28701856a0aa0058e364d3c15c59fcdd25 Mon Sep 17 00:00:00 2001
From: Jonatan Ivanov <jonatan.ivanov@gmail.com>
Date: Fri, 29 Jan 2021 20:52:00 -0800
Subject: [PATCH] Fixing infinite wrapping of LazyTracingFeignClient, see:
 gh-1824 (#1837)

---
 .../client/feign/TraceFeignObjectWrapper.java |  3 +-
 .../feign/TracingFeignObjectWrapperTests.java | 46 +++++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/client/feign/TraceFeignObjectWrapper.java b/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/client/feign/TraceFeignObjectWrapper.java
index fcf0f9d64..f54af344c 100644
--- a/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/client/feign/TraceFeignObjectWrapper.java
+++ b/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/client/feign/TraceFeignObjectWrapper.java
@@ -83,7 +83,8 @@ final class TraceFeignObjectWrapper {
 	}
 
 	Object wrap(Object bean) {
-		if (bean instanceof Client && !(bean instanceof TracingFeignClient)) {
+		if (bean instanceof Client && !(bean instanceof TracingFeignClient)
+				&& !(bean instanceof LazyTracingFeignClient)) {
 			if (ribbonPresent && bean instanceof LoadBalancerFeignClient
 					&& !(bean instanceof TraceLoadBalancerFeignClient)) {
 				return instrumentedFeignRibbonClient(bean);
diff --git a/spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/client/feign/TracingFeignObjectWrapperTests.java b/spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/client/feign/TracingFeignObjectWrapperTests.java
index d355f36dc..1705b77c1 100644
--- a/spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/client/feign/TracingFeignObjectWrapperTests.java
+++ b/spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/client/feign/TracingFeignObjectWrapperTests.java
@@ -30,6 +30,8 @@ import org.springframework.cloud.client.loadbalancer.LoadBalancedRetryFactory;
 import org.springframework.cloud.loadbalancer.blocking.client.BlockingLoadBalancerClient;
 import org.springframework.cloud.openfeign.loadbalancer.FeignBlockingLoadBalancerClient;
 import org.springframework.cloud.openfeign.loadbalancer.RetryableFeignBlockingLoadBalancerClient;
+import org.springframework.cloud.openfeign.ribbon.LoadBalancerFeignClient;
+import org.springframework.test.util.ReflectionTestUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.BDDAssertions.then;
@@ -61,6 +63,19 @@ public class TracingFeignObjectWrapperTests {
 				.isSameAs(notFeignRelatedObject);
 	}
 
+	// gh-1824
+	@Test
+	public void should_not_wrap_nor_modify_lazy_tracing_feign_client() {
+		Client delegate = mock(Client.class);
+		LazyTracingFeignClient lazyTracingFeignClient = new LazyTracingFeignClient(
+				beanFactory, delegate);
+
+		assertThat(traceFeignObjectWrapper.wrap(lazyTracingFeignClient))
+				.isSameAs(lazyTracingFeignClient);
+		assertThat(ReflectionTestUtils.getField(lazyTracingFeignClient, "delegate"))
+				.isSameAs(delegate);
+	}
+
 	// gh-1528
 	@Test
 	public void should_wrap_feign_loadbalancer_client() {
@@ -128,6 +143,29 @@ public class TracingFeignObjectWrapperTests {
 				.isInstanceOf(TraceRetryableFeignBlockingLoadBalancerClient.class);
 	}
 
+	// gh-1824, multiwrap should be ok too
+	@Test
+	public void should_wrap_subclass_of_load_balancer_feign_client() {
+		Client delegate = mock(Client.class);
+		TestLoadBalancerFeignClient testLoadBalancerFeignClient = new TestLoadBalancerFeignClient(
+				delegate);
+
+		traceFeignObjectWrapper.wrap(testLoadBalancerFeignClient);
+		traceFeignObjectWrapper.wrap(testLoadBalancerFeignClient);
+		Object wrapped = traceFeignObjectWrapper.wrap(testLoadBalancerFeignClient);
+		assertThat(wrapped).isExactlyInstanceOf(TraceLoadBalancerFeignClient.class);
+		TraceLoadBalancerFeignClient wrappedClient = (TraceLoadBalancerFeignClient) wrapped;
+		assertThat(wrappedClient.getDelegate()).isSameAs(testLoadBalancerFeignClient);
+		TestLoadBalancerFeignClient firstDelegate = (TestLoadBalancerFeignClient) wrappedClient
+				.getDelegate();
+		assertThat(firstDelegate.getDelegate())
+				.isExactlyInstanceOf(LazyTracingFeignClient.class);
+		LazyTracingFeignClient secondDelegate = (LazyTracingFeignClient) firstDelegate
+				.getDelegate();
+		assertThat(ReflectionTestUtils.getField(secondDelegate, "delegate"))
+				.isSameAs(delegate);
+	}
+
 	static class TestFeignBlockingLoadBalancerClient
 			extends FeignBlockingLoadBalancerClient {
 
@@ -149,4 +187,12 @@ public class TracingFeignObjectWrapperTests {
 
 	}
 
+	static class TestLoadBalancerFeignClient extends LoadBalancerFeignClient {
+
+		TestLoadBalancerFeignClient(Client delegate) {
+			super(delegate, null, null);
+		}
+
+	}
+
 }