feat(lb): deterministic subsetting algorithm to limit the number of i…

…nstances
spring-cloud · Nov 9, 2023 · 6ac12e2 · 6ac12e2
1 parent 75d4691
commit 6ac12e2
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Showing 3 changed files with 31 additions and 8 deletions.
diff --git a/...s/src/main/java/org/springframework/cloud/client/loadbalancer/LoadBalancerProperties.java b/...s/src/main/java/org/springframework/cloud/client/loadbalancer/LoadBalancerProperties.java
@@ -42,6 +42,7 @@
  *
  * @author Olga Maciaszek-Sharma
  * @author Gandhimathi Velusamy
+ * @author Zhuozhi Ji
  * @since 2.2.1
  */
 public class LoadBalancerProperties {
@@ -88,7 +89,8 @@ public class LoadBalancerProperties {
 	private boolean callGetWithRequestOnDelegates = true;
 
 	/**
-	 * Properties for <code>SubsetServiceInstanceListSupplier</code>.
+	 * Properties for
+	 * {@link org.springframework.cloud.loadbalancer.core.SubsetServiceInstanceListSupplier}.
 	 */
 	private Subset subset = new Subset();
 

diff --git a/...va/org/springframework/cloud/loadbalancer/annotation/LoadBalancerClientConfiguration.java b/...va/org/springframework/cloud/loadbalancer/annotation/LoadBalancerClientConfiguration.java
@@ -143,6 +143,15 @@ public ServiceInstanceListSupplier weightedServiceInstanceListSupplier(Configura
 					.build(context);
 		}
 
+		@Bean
+		@ConditionalOnBean(ReactiveDiscoveryClient.class)
+		@ConditionalOnMissingBean
+		@Conditional(SubsetConfigurationCondition.class)
+		public ServiceInstanceListSupplier subsetServiceInstanceListSupplier(ConfigurableApplicationContext context) {
+			return ServiceInstanceListSupplier.builder().withDiscoveryClient().withSubset().withCaching()
+					.build(context);
+		}
+
 	}
 
 	@Configuration(proxyBeanMethods = false)
@@ -353,4 +362,14 @@ public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata)
 
 	}
 
+	static class SubsetConfigurationCondition implements Condition {
+
+		@Override
+		public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
+			return LoadBalancerEnvironmentPropertyUtils.equalToForClientOrDefault(context.getEnvironment(),
+					"configurations", "subset");
+		}
+
+	}
+
 }
diff --git a/...n/java/org/springframework/cloud/loadbalancer/core/SubsetServiceInstanceListSupplier.java b/...n/java/org/springframework/cloud/loadbalancer/core/SubsetServiceInstanceListSupplier.java
@@ -48,13 +48,7 @@ public SubsetServiceInstanceListSupplier(ServiceInstanceListSupplier delegate, P
 			ReactiveLoadBalancer.Factory<ServiceInstance> factory) {
 		super(delegate);
 		LoadBalancerProperties properties = factory.getProperties(getServiceId());
-		String instanceId = properties.getSubset().getInstanceId();
-		if (StringUtils.hasText(instanceId)) {
-			this.instanceId = resolver.resolvePlaceholders(properties.getSubset().getInstanceId());
-		}
-		else {
-			this.instanceId = IdUtils.getDefaultInstanceId(resolver);
-		}
+		this.instanceId = resolveInstanceId(properties, resolver);
 		this.size = properties.getSubset().getSize();
 	}
 
@@ -80,6 +74,14 @@ public Flux<List<ServiceInstance>> get() {
 		});
 	}
 
+	private static String resolveInstanceId(LoadBalancerProperties properties, PropertyResolver resolver) {
+		String instanceId = properties.getSubset().getInstanceId();
+		if (StringUtils.hasText(instanceId)) {
+			return resolver.resolvePlaceholders(properties.getSubset().getInstanceId());
+		}
+		return IdUtils.getDefaultInstanceId(resolver);
+	}
+
 	public String getInstanceId() {
 		return instanceId;
 	}