Renames ServiceInstanceListSuppliers to ServiceInstanceListSupplierBu…

docs/src/main/asciidoc/spring-cloud-commons.adoc

@@ -959,7 +959,7 @@ public class CustomLoadBalancerConfiguration {
 	@Bean
 	public ServiceInstanceListSupplier discoveryClientServiceInstanceListSupplier(
 			ConfigurableApplicationContext context) {
-		return ServiceInstanceListSuppliers.builder()
+		return ServiceInstanceListSupplier.builder()
 					.withDiscoveryClient()
 					.withHealthChecks()
 					.withCaching()
@@ -968,7 +968,7 @@ public class CustomLoadBalancerConfiguration {
 	}
 ----
 
-TIP:: In order to make working on your own LoadBalancer configuration easier, we have added some utility methods in `ServiceInstanceListSuppliers` class.
+TIP:: In order to make working on your own LoadBalancer configuration easier, we have added a `builder()` method to the `ServiceInstanceListSupplier` class.
 
 TIP:: You can also use our alternative predefined configurations in place of the default ones by setting the value of `spring.cloud.loadbalancer.configurations` property to `zone-preference` to use `ZonePreferenceServiceInstanceListSupplier` with caching or to `health-check` to use `HealthCheckServiceInstanceListSupplier` with caching.
 

spring-cloud-loadbalancer/src/main/java/org/springframework/cloud/loadbalancer/annotation/LoadBalancerClientConfiguration.java

@@ -32,7 +32,6 @@
 import org.springframework.cloud.loadbalancer.core.ReactorLoadBalancer;
 import org.springframework.cloud.loadbalancer.core.RoundRobinLoadBalancer;
 import org.springframework.cloud.loadbalancer.core.ServiceInstanceListSupplier;
-import org.springframework.cloud.loadbalancer.core.ServiceInstanceListSuppliers;
 import org.springframework.cloud.loadbalancer.core.ServiceInstanceSupplier;
 import org.springframework.cloud.loadbalancer.support.LoadBalancerClientFactory;
 import org.springframework.context.ApplicationContext;
@@ -75,7 +74,7 @@ public static class ReactiveSupportConfiguration {
 				havingValue = "default", matchIfMissing = true)
 		public ServiceInstanceListSupplier discoveryClientServiceInstanceListSupplier(
 				ConfigurableApplicationContext context) {
-			return ServiceInstanceListSuppliers.builder().withDiscoveryClient()
+			return ServiceInstanceListSupplier.builder().withDiscoveryClient()
 					.withCaching().build(context);
 		}
 
@@ -86,7 +85,7 @@ public ServiceInstanceListSupplier discoveryClientServiceInstanceListSupplier(
 				havingValue = "zone-preference")
 		public ServiceInstanceListSupplier zonePreferenceDiscoveryClientServiceInstanceListSupplier(
 				ConfigurableApplicationContext context) {
-			return ServiceInstanceListSuppliers.builder().withDiscoveryClient()
+			return ServiceInstanceListSupplier.builder().withDiscoveryClient()
 					.withZonePreference().withCaching().build(context);
 		}
 
@@ -97,7 +96,7 @@ public ServiceInstanceListSupplier zonePreferenceDiscoveryClientServiceInstanceL
 				havingValue = "health-check")
 		public ServiceInstanceListSupplier healthCheckDiscoveryClientServiceInstanceListSupplier(
 				ConfigurableApplicationContext context) {
-			return ServiceInstanceListSuppliers.builder().withDiscoveryClient()
+			return ServiceInstanceListSupplier.builder().withDiscoveryClient()
 					.withHealthChecks().withCaching().build(context);
 		}
 
@@ -132,7 +131,7 @@ public static class BlockingSupportConfiguration {
 				havingValue = "default", matchIfMissing = true)
 		public ServiceInstanceListSupplier discoveryClientServiceInstanceListSupplier(
 				ConfigurableApplicationContext context) {
-			return ServiceInstanceListSuppliers.builder().withBlockingDiscoveryClient()
+			return ServiceInstanceListSupplier.builder().withBlockingDiscoveryClient()
 					.withCaching().build(context);
 		}
 
@@ -143,7 +142,7 @@ public ServiceInstanceListSupplier discoveryClientServiceInstanceListSupplier(
 				havingValue = "zone-preference")
 		public ServiceInstanceListSupplier zonePreferenceDiscoveryClientServiceInstanceListSupplier(
 				ConfigurableApplicationContext context) {
-			return ServiceInstanceListSuppliers.builder().withBlockingDiscoveryClient()
+			return ServiceInstanceListSupplier.builder().withBlockingDiscoveryClient()
 					.withZonePreference().withCaching().build(context);
 		}
 
@@ -154,7 +153,7 @@ public ServiceInstanceListSupplier zonePreferenceDiscoveryClientServiceInstanceL
 				havingValue = "health-check")
 		public ServiceInstanceListSupplier healthCheckDiscoveryClientServiceInstanceListSupplier(
 				ConfigurableApplicationContext context) {
-			return ServiceInstanceListSuppliers.builder().withBlockingDiscoveryClient()
+			return ServiceInstanceListSupplier.builder().withBlockingDiscoveryClient()
 					.withHealthChecks().withCaching().build(context);
 		}
 

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

@@ -39,23 +39,32 @@ public interface ServiceInstanceListSupplier
 
 	String getServiceId();
 
+	static ServiceInstanceListSupplierBuilder builder() {
+		return new ServiceInstanceListSupplierBuilder();
+	}
+
 	static FixedServiceInstanceListSupplier.Builder fixed(Environment environment) {
 		return new FixedServiceInstanceListSupplier.Builder(environment);
 	}
 
+	static FixedServiceInstanceListSupplier.SimpleBuilder fixed(String serviceId) {
+		return new FixedServiceInstanceListSupplier.SimpleBuilder(serviceId);
+	}
+
 	class FixedServiceInstanceListSupplier implements ServiceInstanceListSupplier {
 
 		private final String serviceId;
 
 		private List<ServiceInstance> instances;
 
+		@Deprecated
 		public static Builder with(Environment env) {
 			return new Builder(env);
 		}
 
-		private FixedServiceInstanceListSupplier(Environment env,
+		private FixedServiceInstanceListSupplier(String serviceId,
 				List<ServiceInstance> instances) {
-			this.serviceId = env.getProperty(PROPERTY_NAME);
+			this.serviceId = serviceId;
 			this.instances = instances;
 		}
 
@@ -69,6 +78,43 @@ public Flux<List<ServiceInstance>> get() {
 			return Flux.just(instances);
 		}
 
+		@Deprecated
+		public static final class SimpleBuilder {
+
+			private final ArrayList<ServiceInstance> instances = new ArrayList<>();
+
+			private final String serviceId;
+
+			private SimpleBuilder(String serviceId) {
+				this.serviceId = serviceId;
+			}
+
+			public SimpleBuilder instance(ServiceInstance instance) {
+				instances.add(instance);
+				return this;
+			}
+
+			public SimpleBuilder instance(int port) {
+				return instance("localhost", port);
+			}
+
+			public SimpleBuilder instance(String host, int port) {
+				DefaultServiceInstance instance = new DefaultServiceInstance(
+						instanceId(serviceId, host, port), serviceId, host, port, false);
+				return instance(instance);
+			}
+
+			private String instanceId(String serviceId, String host, int port) {
+				return serviceId + ":" + host + ":" + port;
+			}
+
+			public FixedServiceInstanceListSupplier build() {
+				return new FixedServiceInstanceListSupplier(serviceId, instances);
+			}
+
+		}
+
+		@Deprecated
 		public static final class Builder {
 
 			private final Environment env;
@@ -99,7 +145,8 @@ private String instanceId(String serviceId, String host, int port) {
 			}
 
 			public FixedServiceInstanceListSupplier build() {
-				return new FixedServiceInstanceListSupplier(env, instances);
+				return new FixedServiceInstanceListSupplier(
+						env.getProperty(PROPERTY_NAME), instances);
 			}
 
 		}

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

@@ -0,0 +1,229 @@
+/*
+ * Copyright 2013-2020 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;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.BiFunction;
+import java.util.function.Function;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.cloud.client.discovery.DiscoveryClient;
+import org.springframework.cloud.client.discovery.ReactiveDiscoveryClient;
+import org.springframework.cloud.client.loadbalancer.reactive.LoadBalancerProperties;
+import org.springframework.cloud.loadbalancer.cache.LoadBalancerCacheManager;
+import org.springframework.cloud.loadbalancer.config.LoadBalancerZoneConfig;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.util.Assert;
+import org.springframework.web.reactive.function.client.WebClient;
+
+/**
+ * A Builder for creating a {@link ServiceInstanceListSupplier} hierarchy to be used in
+ * {@link ReactorLoadBalancer} configuration.
+ *
+ * @author Spencer Gibb
+ * @author Olga Maciaszek-Sharma
+ */
+public final class ServiceInstanceListSupplierBuilder {
+
+	private static final Log LOG = LogFactory
+			.getLog(ServiceInstanceListSupplierBuilder.class);
+
+	private Creator baseCreator;
+
+	private DelegateCreator cachingCreator;
+
+	private final List<DelegateCreator> creators = new ArrayList<>();
+
+	ServiceInstanceListSupplierBuilder() {
+	}
+
+	/**
+	 * Sets a blocking {@link DiscoveryClient}-based
+	 * {@link DiscoveryClientServiceInstanceListSupplier} as a base
+	 * {@link ServiceInstanceListSupplier} in the hierarchy.
+	 * @return the {@link ServiceInstanceListSupplierBuilder} object
+	 */
+	public ServiceInstanceListSupplierBuilder withBlockingDiscoveryClient() {
+		if (baseCreator != null && LOG.isWarnEnabled()) {
+			LOG.warn(
+					"Overriding a previously set baseCreator with a blocking DiscoveryClient baseCreator.");
+		}
+		this.baseCreator = context -> {
+			DiscoveryClient discoveryClient = context.getBean(DiscoveryClient.class);
+
+			return new DiscoveryClientServiceInstanceListSupplier(discoveryClient,
+					context.getEnvironment());
+		};
+		return this;
+	}
+
+	/**
+	 * Sets a {@link ReactiveDiscoveryClient}-based
+	 * {@link DiscoveryClientServiceInstanceListSupplier} as a base
+	 * {@link ServiceInstanceListSupplier} in the hierarchy.
+	 * @return the {@link ServiceInstanceListSupplierBuilder} object
+	 */
+	public ServiceInstanceListSupplierBuilder withDiscoveryClient() {
+		if (baseCreator != null && LOG.isWarnEnabled()) {
+			LOG.warn(
+					"Overriding a previously set baseCreator with a ReactiveDiscoveryClient baseCreator.");
+		}
+		this.baseCreator = context -> {
+			ReactiveDiscoveryClient discoveryClient = context
+					.getBean(ReactiveDiscoveryClient.class);
+
+			return new DiscoveryClientServiceInstanceListSupplier(discoveryClient,
+					context.getEnvironment());
+		};
+		return this;
+	}
+
+	/**
+	 * Sets a user-provided {@link ServiceInstanceListSupplier} as a base
+	 * {@link ServiceInstanceListSupplier} in the hierarchy.
+	 * @param supplier a user-provided {@link ServiceInstanceListSupplier} instance
+	 * @return the {@link ServiceInstanceListSupplierBuilder} object
+	 */
+	public ServiceInstanceListSupplierBuilder withBase(
+			ServiceInstanceListSupplier supplier) {
+		this.baseCreator = context -> supplier;
+		return this;
+	}
+
+	/**
+	 * Adds a {@link HealthCheckServiceInstanceListSupplier} to the
+	 * {@link ServiceInstanceListSupplier} hierarchy.
+	 * @return the {@link ServiceInstanceListSupplierBuilder} object
+	 */
+	public ServiceInstanceListSupplierBuilder withHealthChecks() {
+		DelegateCreator creator = (context, delegate) -> {
+			LoadBalancerProperties properties = context
+					.getBean(LoadBalancerProperties.class);
+			WebClient.Builder webClient = context.getBean(WebClient.Builder.class);
+			return new HealthCheckServiceInstanceListSupplier(delegate,
+					properties.getHealthCheck(), webClient.build());
+		};
+		this.creators.add(creator);
+		return this;
+	}
+
+	/**
+	 * Adds a {@link HealthCheckServiceInstanceListSupplier} that uses user-provided
+	 * {@link WebClient} instance to the {@link ServiceInstanceListSupplier} hierarchy.
+	 * @param webClient a user-provided {@link WebClient} instance
+	 * @return the {@link ServiceInstanceListSupplierBuilder} object
+	 */
+	public ServiceInstanceListSupplierBuilder withHealthChecks(WebClient webClient) {
+		DelegateCreator creator = (context, delegate) -> {
+			LoadBalancerProperties properties = context
+					.getBean(LoadBalancerProperties.class);
+			return new HealthCheckServiceInstanceListSupplier(delegate,
+					properties.getHealthCheck(), webClient);
+		};
+		this.creators.add(creator);
+		return this;
+	}
+
+	/**
+	 * Adds a {@link ZonePreferenceServiceInstanceListSupplier} to the
+	 * {@link ServiceInstanceListSupplier} hierarchy.
+	 * @return the {@link ServiceInstanceListSupplierBuilder} object
+	 */
+	public ServiceInstanceListSupplierBuilder withZonePreference() {
+		DelegateCreator creator = (context, delegate) -> {
+			LoadBalancerZoneConfig zoneConfig = context
+					.getBean(LoadBalancerZoneConfig.class);
+			return new ZonePreferenceServiceInstanceListSupplier(delegate, zoneConfig);
+		};
+		this.creators.add(creator);
+		return this;
+	}
+
+	/**
+	 * If {@link LoadBalancerCacheManager} is available in the context, wraps created
+	 * {@link ServiceInstanceListSupplier} hierarchy with a
+	 * {@link CachingServiceInstanceListSupplier} instance to provide a caching mechanism
+	 * for service instances. Uses {@link ObjectProvider} to lazily resolve
+	 * {@link LoadBalancerCacheManager}.
+	 * @return the {@link ServiceInstanceListSupplierBuilder} object
+	 */
+	public ServiceInstanceListSupplierBuilder withCaching() {
+		if (cachingCreator != null && LOG.isWarnEnabled()) {
+			LOG.warn(
+					"Overriding a previously set cachingCreator with a CachingServiceInstanceListSupplier-based cachingCreator.");
+		}
+		this.cachingCreator = (context, delegate) -> {
+			ObjectProvider<LoadBalancerCacheManager> cacheManagerProvider = context
+					.getBeanProvider(LoadBalancerCacheManager.class);
+			if (cacheManagerProvider.getIfAvailable() != null) {
+				return new CachingServiceInstanceListSupplier(delegate,
+						cacheManagerProvider.getIfAvailable());
+			}
+			if (LOG.isWarnEnabled()) {
+				LOG.warn(
+						"LoadBalancerCacheManager not available, returning delegate without caching.");
+			}
+			return delegate;
+		};
+		return this;
+	}
+
+	/**
+	 * Builds the {@link ServiceInstanceListSupplier} hierarchy.
+	 * @param context application context
+	 * @return a {@link ServiceInstanceListSupplier} instance on top of the delegate
+	 * hierarchy
+	 */
+	public ServiceInstanceListSupplier build(ConfigurableApplicationContext context) {
+		Assert.notNull(baseCreator, "A baseCreator must not be null");
+
+		ServiceInstanceListSupplier supplier = baseCreator.apply(context);
+
+		for (DelegateCreator creator : creators) {
+			supplier = creator.apply(context, supplier);
+		}
+
+		if (this.cachingCreator != null) {
+			supplier = this.cachingCreator.apply(context, supplier);
+		}
+		return supplier;
+	}
+
+	/**
+	 * Allows creating a {@link ServiceInstanceListSupplier} instance based on provided
+	 * {@link ConfigurableApplicationContext}.
+	 */
+	public interface Creator extends
+			Function<ConfigurableApplicationContext, ServiceInstanceListSupplier> {
+
+	}
+
+	/**
+	 * Allows creating a {@link ServiceInstanceListSupplier} instance based on provided
+	 * {@link ConfigurableApplicationContext} and another
+	 * {@link ServiceInstanceListSupplier} instance that will be used as a delegate.
+	 */
+	public interface DelegateCreator extends
+			BiFunction<ConfigurableApplicationContext, ServiceInstanceListSupplier, ServiceInstanceListSupplier> {
+
+	}
+
+}