Adds RouteDeletedEvent used in WeightCalculatorWebFilter

Fixes gh-922

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/actuate/AbstractGatewayControllerEndpoint.java

@@ -34,6 +34,7 @@
 
 import org.springframework.boot.actuate.autoconfigure.endpoint.web.WebEndpointProperties;
 import org.springframework.cloud.gateway.event.RefreshRoutesEvent;
+import org.springframework.cloud.gateway.event.RouteDeletedEvent;
 import org.springframework.cloud.gateway.filter.FilterDefinition;
 import org.springframework.cloud.gateway.filter.GlobalFilter;
 import org.springframework.cloud.gateway.filter.factory.GatewayFilterFactory;
@@ -307,9 +308,10 @@ private boolean isAvailable(PredicateDefinition predicateDefinition) {
 
 	@DeleteMapping("/routes/{id}")
 	public Mono<ResponseEntity<Object>> delete(@PathVariable String id) {
-		return this.routeDefinitionWriter.delete(Mono.just(id))
-				.then(Mono.defer(() -> Mono.just(ResponseEntity.ok().build())))
-				.onErrorResume(t -> t instanceof NotFoundException, t -> Mono.just(ResponseEntity.notFound().build()));
+		return this.routeDefinitionWriter.delete(Mono.just(id)).then(Mono.defer(() -> {
+			publisher.publishEvent(new RouteDeletedEvent(this, id));
+			return Mono.just(ResponseEntity.ok().build());
+		})).onErrorResume(t -> t instanceof NotFoundException, t -> Mono.just(ResponseEntity.notFound().build()));
 	}
 
 	@GetMapping("/routes/{id}/combinedfilters")

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/event/RouteDeletedEvent.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2013-2024 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.gateway.event;
+
+import org.springframework.context.ApplicationEvent;
+
+public class RouteDeletedEvent extends ApplicationEvent {
+
+	private final String routeId;
+
+	public RouteDeletedEvent(Object source, String routeId) {
+		super(source);
+		this.routeId = routeId;
+	}
+
+	public String getRouteId() {
+		return routeId;
+	}
+
+}

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/filter/WeightCalculatorWebFilter.java

@@ -35,13 +35,15 @@
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.cloud.gateway.event.PredicateArgsEvent;
 import org.springframework.cloud.gateway.event.RefreshRoutesEvent;
+import org.springframework.cloud.gateway.event.RouteDeletedEvent;
 import org.springframework.cloud.gateway.event.WeightDefinedEvent;
 import org.springframework.cloud.gateway.route.RouteLocator;
 import org.springframework.cloud.gateway.support.ConfigurationService;
 import org.springframework.cloud.gateway.support.WeightConfig;
 import org.springframework.context.ApplicationEvent;
 import org.springframework.context.event.SmartApplicationListener;
 import org.springframework.core.Ordered;
+import org.springframework.core.log.LogMessage;
 import org.springframework.core.style.ToStringCreator;
 import org.springframework.util.Assert;
 import org.springframework.web.server.ServerWebExchange;
@@ -123,6 +125,8 @@ public boolean supportsEventType(Class<? extends ApplicationEvent> eventType) {
 		return PredicateArgsEvent.class.isAssignableFrom(eventType) ||
 		// from java dsl
 				WeightDefinedEvent.class.isAssignableFrom(eventType) ||
+				// from actuator or custom call
+				RouteDeletedEvent.class.isAssignableFrom(eventType) ||
 				// force initialization
 				RefreshRoutesEvent.class.isAssignableFrom(eventType);
 	}
@@ -140,6 +144,9 @@ public void onApplicationEvent(ApplicationEvent event) {
 		else if (event instanceof WeightDefinedEvent) {
 			addWeightConfig(((WeightDefinedEvent) event).getWeightConfig());
 		}
+		else if (event instanceof RouteDeletedEvent) {
+			removeWeightConfig(((RouteDeletedEvent) event).getRouteId());
+		}
 		else if (event instanceof RefreshRoutesEvent && routeLocator != null) {
 			// forces initialization
 			if (routeLocatorInitialized.compareAndSet(false, true)) {
@@ -229,6 +236,16 @@ private boolean hasRelevantKey(Map<String, Object> args) {
 		groupWeights.put(group, config);
 	}
 
+	private void removeWeightConfig(String routeId) {
+		log.trace(LogMessage.format("Removing weight config for route %s", routeId));
+		groupWeights.forEach((group, weightConfig) -> {
+			if (weightConfig.normalizedWeights.containsKey(routeId)) {
+				weightConfig.normalizedWeights.remove(routeId);
+				weightConfig.weights.remove(routeId);
+			}
+		});
+	}
+
 	/* for testing */ Map<String, GroupWeightConfig> getGroupWeights() {
 		return groupWeights;
 	}

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/filter/WeightCalculatorWebFilterTests.java

@@ -24,6 +24,7 @@
 import org.junit.jupiter.api.Test;
 
 import org.springframework.cloud.gateway.event.PredicateArgsEvent;
+import org.springframework.cloud.gateway.event.RouteDeletedEvent;
 import org.springframework.cloud.gateway.filter.WeightCalculatorWebFilter.GroupWeightConfig;
 import org.springframework.cloud.gateway.support.ConfigurationService;
 import org.springframework.cloud.gateway.support.WeightConfig;
@@ -121,6 +122,12 @@ public void testChooseRouteWithRandom() {
 		filter.filter(exchange, filterChain);
 		weights = WeightCalculatorWebFilter.getWeights(exchange);
 		assertThat(weights).containsEntry("groupa", "route3");
+
+		filter.onApplicationEvent(new RouteDeletedEvent(this, "route3"));
+		assertThat(filter.getGroupWeights()).containsKey("groupa");
+		GroupWeightConfig groupa = filter.getGroupWeights().get("groupa");
+		assertThat(groupa.normalizedWeights).doesNotContainKey("route3");
+		assertThat(groupa.weights).doesNotContainKey("route3");
 	}
 
 	@Test