feat: support least connection loadbalancer

spring-cloud-starter-tencent-polaris-discovery/src/main/java/com/tencent/cloud/polaris/loadbalancer/PolarisLoadBalancerClientConfiguration.java

@@ -105,6 +105,15 @@ public class PolarisLoadBalancerClientConfiguration {
 	}
 	@Bean
 	@ConditionalOnMissingBean
+	@ConditionalOnProperty(value = "spring.cloud.polaris.loadbalancer.strategy", havingValue = "polarisLeastConnection")
+	public ReactorLoadBalancer<ServiceInstance> polarisLeastConnectionLoadBalancer(Environment environment,
+			LoadBalancerClientFactory loadBalancerClientFactory, PolarisSDKContextManager polarisSDKContextManager) {
+		String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
+		return new PolarisShortestLeastConnectionLoadBalancer(name,
+				loadBalancerClientFactory.getLazyProvider(name, ServiceInstanceListSupplier.class), polarisSDKContextManager.getRouterAPI());
+	}
+	@Bean
+	@ConditionalOnMissingBean
 	@ConditionalOnProperty(value = "spring.cloud.polaris.loadbalancer.strategy", havingValue = "polarisWeightedRoundRobin", matchIfMissing = true)
 	public ReactorLoadBalancer<ServiceInstance> polarisWeightedRoundRobinLoadBalancer(Environment environment,
 			LoadBalancerClientFactory loadBalancerClientFactory, PolarisSDKContextManager polarisSDKContextManager) {
@@ -113,6 +122,7 @@ public class PolarisLoadBalancerClientConfiguration {
 				loadBalancerClientFactory.getLazyProvider(name, ServiceInstanceListSupplier.class), polarisSDKContextManager.getRouterAPI());
 	}
 
+
 	@Configuration(proxyBeanMethods = false)
 	@ConditionalOnReactiveDiscoveryEnabled
 	@Order(REACTIVE_SERVICE_INSTANCE_SUPPLIER_ORDER)

spring-cloud-starter-tencent-polaris-discovery/src/main/java/com/tencent/cloud/polaris/loadbalancer/PolarisShortestLeastConnectionLoadBalancer.java

@@ -0,0 +1,27 @@
+package com.tencent.cloud.polaris.loadbalancer;
+
+import com.tencent.polaris.api.config.consumer.LoadBalanceConfig;
+import com.tencent.polaris.api.rpc.Criteria;
+import com.tencent.polaris.router.api.core.RouterAPI;
+import com.tencent.polaris.router.api.rpc.ProcessLoadBalanceRequest;
+
+import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.cloud.loadbalancer.core.ServiceInstanceListSupplier;
+
+/**
+ * PolarisShortestResponseTimeLoadBalancer.
+ *
+ * @author Yuwei Fu
+ */
+public class PolarisShortestLeastConnectionLoadBalancer extends AbstractPolarisLoadBalancer {
+	public PolarisShortestLeastConnectionLoadBalancer(String serviceId, ObjectProvider<ServiceInstanceListSupplier> supplierObjectProvider, RouterAPI routerAPI) {
+		super(serviceId, supplierObjectProvider, routerAPI);
+	}
+
+	@Override
+	protected ProcessLoadBalanceRequest setProcessLoadBalanceRequest(ProcessLoadBalanceRequest req) {
+		req.setLbPolicy(LoadBalanceConfig.LOAD_BALANCE_LEAST_CONNECTION);
+		req.setCriteria(new Criteria());
+		return req;
+	}
+}

spring-cloud-tencent-rpc-enhancement/src/main/java/com/tencent/cloud/rpc/enhancement/instrument/resttemplate/EnhancedRestTemplateWrapInterceptor.java

@@ -122,6 +122,8 @@ public class EnhancedRestTemplateWrapInterceptor {
 		catch (IOException e) {
 			enhancedPluginContext.setDelay(System.currentTimeMillis() - startMillis);
 			enhancedPluginContext.setThrowable(e);
+			enhancedPluginContext.setTargetServiceInstance((ServiceInstance) MetadataContextHolder.get()
+					.getLoadbalancerMetadata().get(LOAD_BALANCER_SERVICE_INSTANCE), request.getURI());
 			// Run exception enhanced plugins.
 			pluginRunner.run(EnhancedPluginType.Client.EXCEPTION, enhancedPluginContext);
 			throw e;