http-netty: use DefaultLoadBalancer API's

servicetalk-http-netty/src/main/java/io/servicetalk/http/netty/DefaultSingleAddressHttpClientBuilder.java

@@ -54,7 +54,8 @@
 import io.servicetalk.http.netty.ReservableRequestConcurrencyControllers.InternalRetryingHttpClientFilter;
 import io.servicetalk.http.utils.HostHeaderHttpRequesterFilter;
 import io.servicetalk.http.utils.IdleTimeoutConnectionFilter;
-import io.servicetalk.loadbalancer.RoundRobinLoadBalancers;
+import io.servicetalk.loadbalancer.LoadBalancers;
+import io.servicetalk.loadbalancer.OutlierDetectorConfigs;
 import io.servicetalk.logging.api.LogLevel;
 import io.servicetalk.transport.api.ClientSslConfig;
 import io.servicetalk.transport.api.DomainSocketAddress;
@@ -839,8 +840,11 @@ default StreamingHttpClientFilter create(FilterableStreamingHttpClient client) {
 
     private static <ResolvedAddress> HttpLoadBalancerFactory<ResolvedAddress> defaultLoadBalancer() {
         return new DefaultHttpLoadBalancerFactory<>(
-                RoundRobinLoadBalancers.<ResolvedAddress, FilterableStreamingHttpLoadBalancedConnection>builder(
-                                DefaultHttpLoadBalancerFactory.class.getSimpleName()).build());
+                LoadBalancers.<ResolvedAddress, FilterableStreamingHttpLoadBalancedConnection>builder(
+                        DefaultHttpLoadBalancerFactory.class.getSimpleName())
+                        // For now, only use the l4 detection to reproduce the old RoundRobinLoadBalancer behavior
+                        .outlierDetectorConfig(OutlierDetectorConfigs.l4Only())
+                        .build());
     }
 
     // Because of the change in https://github.com/apple/servicetalk/pull/2379, we should constrain the type back to

servicetalk-http-netty/src/main/java/io/servicetalk/http/netty/HttpClients.java

@@ -41,7 +41,8 @@
 import io.servicetalk.http.api.ProxyConfig;
 import io.servicetalk.http.api.SingleAddressHttpClientBuilder;
 import io.servicetalk.http.api.StreamingHttpRequest;
-import io.servicetalk.loadbalancer.RoundRobinLoadBalancers;
+import io.servicetalk.loadbalancer.LoadBalancers;
+import io.servicetalk.loadbalancer.OutlierDetectorConfigs;
 import io.servicetalk.transport.api.HostAndPort;
 import io.servicetalk.transport.api.TransportObserver;
 
@@ -485,12 +486,14 @@ private static <U, R> SingleAddressHttpClientBuilder<U, R> forSingleAddress(
                         .retryServiceDiscoveryErrors(NoRetriesStrategy.INSTANCE)
                         // Disable health-checking:
                         .loadBalancerFactory(new DefaultHttpLoadBalancerFactory<>(
-                                RoundRobinLoadBalancers.<R, FilterableStreamingHttpLoadBalancedConnection>builder(
+                                LoadBalancers.<R, FilterableStreamingHttpLoadBalancedConnection>builder(
                                         // Use a different ID to let providers distinguish this LB from the default one
                                         DefaultHttpLoadBalancerFactory.class.getSimpleName() + '-' +
                                                 DiscoveryStrategy.ON_NEW_CONNECTION.name())
-                                        .healthCheckFailedConnectionsThreshold(-1)
-                                        .build()))
+                                                // Disable all outlier detection since we're really using the
+                                                // Host as the load balancer and not the LoadBalancer itself.
+                                                .outlierDetectorConfig(OutlierDetectorConfigs.disabled())
+                                                .build()))
                         .appendConnectionFactoryFilter(resolvingConnectionFactory.get());
             default:
                 throw new IllegalArgumentException("Unsupported strategy: " + discoveryStrategy);

servicetalk-loadbalancer/src/main/java/io/servicetalk/loadbalancer/OutlierDetectorConfigs.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright © 2025 Apple Inc. and the ServiceTalk project 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
+ *
+ *   http://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 io.servicetalk.loadbalancer;
+
+import java.time.Duration;
+
+/**
+ * Useful default {@link OutlierDetectorConfig} values.
+ *
+ * The configuration values can be used as a base layer for configuration and then modified using the
+ * {@link OutlierDetectorConfig.Builder} constructor as follows:
+ * <pre>{@code
+ *     OutlierDetectorConfig config = new OutlierDetectorConfig.Builder(disabled())
+ *          .failedConnectionsThreshold(2)
+ *          .build();
+ * }</pre>
+ */
+public final class OutlierDetectorConfigs {
+
+    private static final OutlierDetectorConfig L4_ONLY =
+            new OutlierDetectorConfig.Builder()
+                .ewmaHalfLife(Duration.ZERO)
+                .enforcingFailurePercentage(0)
+                .enforcingSuccessRate(0)
+                .enforcingConsecutive5xx(0)
+                .build();
+
+    private static final OutlierDetectorConfig DISABLED =
+            new OutlierDetectorConfig.Builder(L4_ONLY)
+                    .failedConnectionsThreshold(-1)
+                    .build();
+
+    private OutlierDetectorConfigs() {
+        // no instances
+    }
+
+    /**
+     * {@link OutlierDetectorConfig} that only enables the default consecutive connection failure detection.
+     * @return the {@link OutlierDetectorConfig}
+     */
+    public static OutlierDetectorConfig l4Only() {
+        return L4_ONLY;
+    }
+
+    /**
+     * {@link OutlierDetectorConfig} that disables all outlier detection.
+     * @return the {@link OutlierDetectorConfig}
+     */
+    public static OutlierDetectorConfig disabled() {
+        return DISABLED;
+    }
+}

servicetalk-loadbalancer/src/main/java/io/servicetalk/loadbalancer/RoundRobinLoadBalancerFactory.java

@@ -139,13 +139,10 @@ private <T extends C> LoadBalancer<T> buildDefaultLoadBalancerFactory(
             backgroundExecutor = healthCheckConfig.executor;
         }
 
-        OutlierDetectorConfig outlierDetectorConfig = new OutlierDetectorConfig.Builder()
-                .ewmaHalfLife(Duration.ZERO)
-                // disable the xDS outlier detectors
-                .enforcingFailurePercentage(0)
-                .enforcingSuccessRate(0)
-                .enforcingConsecutive5xx(0)
-                // set the ServiceTalk L4 connection outlier detector settings
+        OutlierDetectorConfig outlierDetectorConfig =
+                // Start with outlier detection disabled. When we set failedConnectionsThreshold it may turn
+                // L4 outlier detection back on.
+                new OutlierDetectorConfig.Builder(OutlierDetectorConfigs.disabled())
                 .failedConnectionsThreshold(healthCheckFailedConnectionsThreshold)
                 .failureDetectorInterval(healthCheckInterval, healthCheckJitter)
                 .serviceDiscoveryResubscribeInterval(healthCheckResubscribeInterval, healthCheckResubscribeJitter)