Fix DelegatingServiceInstanceListSupplier must (#1226)

spring-cloud-loadbalancer/src/main/java/org/springframework/cloud/loadbalancer/core/DelegatingServiceInstanceListSupplier.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2023 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.
@@ -18,6 +18,7 @@ package org.springframework.cloud.loadbalancer.core;
 
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.cloud.client.ServiceInstance;
 import org.springframework.util.Assert;
 
 /**
@@ -26,9 +27,10 @@ import org.springframework.util.Assert;
  *
  * @author Spencer Gibb
  * @author Olga Maciaszek-Sharma
+ * @author Jürgen Kreitler
  */
 public abstract class DelegatingServiceInstanceListSupplier
-		implements ServiceInstanceListSupplier, InitializingBean, DisposableBean {
+		implements ServiceInstanceListSupplier, SelectedInstanceCallback, InitializingBean, DisposableBean {
 
 	protected final ServiceInstanceListSupplier delegate;
 
@@ -46,6 +48,13 @@ public abstract class DelegatingServiceInstanceListSupplier
 		return this.delegate.getServiceId();
 	}
 
+	@Override
+	public void selectedServiceInstance(ServiceInstance serviceInstance) {
+		if (delegate instanceof SelectedInstanceCallback selectedInstanceCallbackDelegate) {
+			selectedInstanceCallbackDelegate.selectedServiceInstance(serviceInstance);
+		}
+	}
+
 	@Override
 	public void afterPropertiesSet() throws Exception {
 		if (delegate instanceof InitializingBean) {

spring-cloud-loadbalancer/src/main/java/org/springframework/cloud/loadbalancer/core/SameInstancePreferenceServiceInstanceListSupplier.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2023 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.
@@ -30,6 +30,7 @@ import org.springframework.cloud.client.ServiceInstance;
  * chosen instance if it's available.
  *
  * @author Olga Maciaszek-Sharma
+ * @author Jürgen Kreitler
  * @since 2.2.7
  */
 public class SameInstancePreferenceServiceInstanceListSupplier extends DelegatingServiceInstanceListSupplier
@@ -72,6 +73,7 @@ public class SameInstancePreferenceServiceInstanceListSupplier extends Delegatin
 
 	@Override
 	public void selectedServiceInstance(ServiceInstance serviceInstance) {
+		super.selectedServiceInstance(serviceInstance);
 		if (previouslyReturnedInstance == null || !previouslyReturnedInstance.equals(serviceInstance)) {
 			previouslyReturnedInstance = serviceInstance;
 		}

spring-cloud-loadbalancer/src/test/java/org/springframework/cloud/loadbalancer/core/RetryAwareServiceInstanceListSupplierTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2023 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.
@@ -27,11 +27,16 @@ import org.springframework.cloud.client.loadbalancer.RetryableRequestContext;
 import org.springframework.cloud.loadbalancer.support.ServiceInstanceListSuppliers;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
 
 /**
  * Tests for {@link RetryAwareServiceInstanceListSupplier}.
  *
  * @author Olga Maciaszek-Sharma
+ * @author Jürgen Kreitler
  */
 class RetryAwareServiceInstanceListSupplierTests {
 
@@ -78,4 +83,12 @@ class RetryAwareServiceInstanceListSupplierTests {
 		assertThat(returnedInstances).containsExactly(firstInstance);
 	}
 
+	@Test
+	void shouldCallSelectedServiceInstanceOnItsDelegate() {
+		ServiceInstance firstInstance = instance(serviceId, "1host", false);
+		TestSelectedServiceInstanceSupplier delegate = mock(TestSelectedServiceInstanceSupplier.class);
+		DelegatingServiceInstanceListSupplier supplier = new RetryAwareServiceInstanceListSupplier(delegate);
+		supplier.selectedServiceInstance(firstInstance);
+		verify(delegate, times(1)).selectedServiceInstance(any(ServiceInstance.class));
+	}
 }

spring-cloud-loadbalancer/src/test/java/org/springframework/cloud/loadbalancer/core/RoundRobinLoadBalancerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2023 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.
@@ -32,10 +32,13 @@ import static java.lang.Integer.MIN_VALUE;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
 /**
  * @author Zhuozhi JI
+ * @author Jürgen Kreitler
  */
 class RoundRobinLoadBalancerTests {
 
@@ -68,6 +71,18 @@ class RoundRobinLoadBalancerTests {
 		assertThat(loadBalancer.position).hasValue(0);
 	}
 
+	@Test
+	void shouldCallSelectedServiceInstanceIfSupplierOrItsDelegateIsInstanceOf() {
+		TestSelectedServiceInstanceSupplier delegate = mock(TestSelectedServiceInstanceSupplier.class);
+		DelegatingServiceInstanceListSupplier supplier = new RetryAwareServiceInstanceListSupplier(delegate);
+		when(delegate.get(any())).thenReturn(Flux.just(Collections.singletonList(new DefaultServiceInstance())));
+		RoundRobinLoadBalancer loadBalancer = new RoundRobinLoadBalancer(new SimpleObjectProvider<>(supplier),
+				"shouldNotMovePositionIfOnlyOneInstance", 0);
+
+		loadBalancer.choose().block();
+		verify(delegate, times(1)).selectedServiceInstance(any(ServiceInstance.class));
+	}
+
 	@SuppressWarnings("all")
 	void assertOrderEnforced(int seed) {
 		List<ServiceInstance> instances = new ArrayList<>();

spring-cloud-loadbalancer/src/test/java/org/springframework/cloud/loadbalancer/core/SameInstancePreferenceServiceInstanceListSupplierTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2023 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.
@@ -26,13 +26,17 @@ import org.springframework.cloud.client.DefaultServiceInstance;
 import org.springframework.cloud.client.ServiceInstance;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
 /**
  * Tests for {@link SameInstancePreferenceServiceInstanceListSupplier}.
  *
  * @author Olga Maciaszek-Sharma
+ * @author Jürgen Kreitler
  */
 class SameInstancePreferenceServiceInstanceListSupplierTests {
 
@@ -78,6 +82,15 @@ class SameInstancePreferenceServiceInstanceListSupplierTests {
 		assertThat(instances).hasSize(2);
 	}
 
+	@Test
+	void shouldCallSelectedServiceInstanceOnItsDelegate() {
+		ServiceInstance firstInstance = serviceInstance("test-4");
+		TestSelectedServiceInstanceSupplier delegate = mock(TestSelectedServiceInstanceSupplier.class);
+		DelegatingServiceInstanceListSupplier supplier = new SameInstancePreferenceServiceInstanceListSupplier(delegate);
+		supplier.selectedServiceInstance(firstInstance);
+		verify(delegate, times(1)).selectedServiceInstance(any(ServiceInstance.class));
+	}
+
 	private DefaultServiceInstance serviceInstance(String instanceId) {
 		return new DefaultServiceInstance(instanceId, "test", "http://test.test", 9080, false);
 	}

spring-cloud-loadbalancer/src/test/java/org/springframework/cloud/loadbalancer/core/TestSelectedServiceInstanceSupplier.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2012-2023 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
+ *
+ *      https://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.loadbalancer.core;
+
+/**
+ * Test supplier interface extending {@link ServiceInstanceListSupplier} and {@link SelectedInstanceCallback}.
+ * Useful if you need to verify certain behavior happened on a mock for example.
+ *
+ * @author Jürgen Kreitler
+ */
+public interface TestSelectedServiceInstanceSupplier extends ServiceInstanceListSupplier, SelectedInstanceCallback {
+}