loadbalancer: move DefaultLoadBalancer to its own experimental module

servicetalk-loadbalancer-experimental/build.gradle

@@ -0,0 +1,43 @@
+/*
+ * Copyright © 2018-2019 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.
+ */
+
+apply plugin: "io.servicetalk.servicetalk-gradle-plugin-internal-library"
+
+dependencies {
+  implementation platform(project(":servicetalk-dependencies"))
+  testImplementation enforcedPlatform("org.junit:junit-bom:$junit5Version")
+
+  api project(":servicetalk-client-api")
+  api project(":servicetalk-concurrent-api")
+
+  implementation project(":servicetalk-annotations")
+  implementation project(":servicetalk-concurrent-api-internal")
+  implementation project(":servicetalk-concurrent-internal")
+  implementation project(":servicetalk-loadbalancer")
+  implementation project(":servicetalk-utils-internal")
+  implementation "com.google.code.findbugs:jsr305"
+  implementation "org.slf4j:slf4j-api"
+
+  testImplementation testFixtures(project(":servicetalk-concurrent-api"))
+  testImplementation testFixtures(project(":servicetalk-concurrent-internal"))
+  testImplementation project(":servicetalk-concurrent-test-internal")
+  testImplementation project(":servicetalk-test-resources")
+  testImplementation "org.junit.jupiter:junit-jupiter-api"
+  testImplementation "org.junit.jupiter:junit-jupiter-params"
+  testImplementation "org.apache.logging.log4j:log4j-core"
+  testImplementation "org.hamcrest:hamcrest:$hamcrestVersion"
+  testImplementation "org.mockito:mockito-core:$mockitoCoreVersion"
+}

servicetalk-loadbalancer-experimental/gradle/spotbugs/test-exclusions.xml

@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright © 2019 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.
+  -->
+<FindBugsFilter>
+  <!-- Fields are usually initialized in @BeforeClass/@Before methods instead of constructors for tests -->
+  <Match>
+    <Source name="~.*Test\.java"/>
+    <Bug pattern="NP_NONNULL_FIELD_NOT_INITIALIZED_IN_CONSTRUCTOR"/>
+  </Match>
+  <Match>
+    <Source name="~.*Test\.java"/>
+    <Bug pattern="THROWS_METHOD_THROWS_RUNTIMEEXCEPTION"/>
+  </Match>
+  <Match>
+    <Source name="~.*Test\.java"/>
+    <Bug pattern="THROWS_METHOD_THROWS_CLAUSE_BASIC_EXCEPTION"/>
+  </Match>
+  <Match>
+    <Source name="~.*Test\.java"/>
+    <Bug pattern="THROWS_METHOD_THROWS_CLAUSE_THROWABLE"/>
+  </Match>
+</FindBugsFilter>

servicetalk-loadbalancer/src/main/java/io/servicetalk/loadbalancer/ErrorClass.java → servicetalk-loadbalancer-experimental/src/main/java/io/servicetalk/loadbalancer/ErrorClass.java

@@ -18,7 +18,7 @@
 /**
  * Enumeration of the main failure classes.
  */
-enum ErrorClass {
+public enum ErrorClass {
 
     /**
      * Failures related to locally enforced timeouts that prevent session establishment with the peer.

servicetalk-loadbalancer/src/main/java/io/servicetalk/loadbalancer/RequestTracker.java → servicetalk-loadbalancer-experimental/src/main/java/io/servicetalk/loadbalancer/RequestTracker.java

@@ -24,13 +24,13 @@
  * - At initiation of an action for which a request is must call {@link RequestTracker#beforeStart()} and save the
  *   timestamp much like would be done when using a stamped lock.
  * - Once the request event is complete only one of the {@link RequestTracker#onSuccess(long)} or
- *   {@link RequestTracker#onError(long, ErrorClass, Throwable)} methods must be called and called exactly once.
+ *   {@link RequestTracker#onError(long, ErrorClass)} methods must be called and called exactly once.
  * In other words, every call to {@link RequestTracker#beforeStart()} must be followed by exactly one call to either of
  * the completion methods {@link RequestTracker#onSuccess(long)} or
- * {@link RequestTracker#onError(long, ErrorClass, Throwable)}. Failure to do so can cause state corruption in the
+ * {@link RequestTracker#onError(long, ErrorClass)}. Failure to do so can cause state corruption in the
  * {@link RequestTracker} implementations which may track not just latency but also the outstanding requests.
  */
-interface RequestTracker {
+public interface RequestTracker {
 
     ContextMap.Key<RequestTracker> REQUEST_TRACKER_KEY =
             ContextMap.Key.newKey("request_tracker", RequestTracker.class);

servicetalk-loadbalancer-experimental/src/main/java/io/servicetalk/loadbalancer/package-info.java

@@ -0,0 +1,19 @@
+/*
+ * Copyright © 2018 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.
+ */
+@ElementsAreNonnullByDefault
+package io.servicetalk.loadbalancer;
+
+import io.servicetalk.annotations.ElementsAreNonnullByDefault;

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

@@ -28,7 +28,6 @@
 
 import java.time.Duration;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.ThreadPoolExecutor;
 import javax.annotation.Nullable;
@@ -58,17 +57,14 @@ public final class RoundRobinLoadBalancerFactory<ResolvedAddress, C extends Load
 
     private final String id;
     private final int linearSearchSpace;
-    private final boolean useNewRoundRobin;
     @Nullable
     private final HealthCheckConfig healthCheckConfig;
 
     private RoundRobinLoadBalancerFactory(final String id,
                                           final int linearSearchSpace,
-                                          final boolean useNewRoundRobin,
                                           @Nullable final HealthCheckConfig healthCheckConfig) {
         this.id = id;
         this.linearSearchSpace = linearSearchSpace;
-        this.useNewRoundRobin = useNewRoundRobin;
         this.healthCheckConfig = healthCheckConfig;
     }
 
@@ -78,30 +74,10 @@ public <T extends C> LoadBalancer<T> newLoadBalancer(
             final String targetResource,
             final Publisher<? extends Collection<? extends ServiceDiscovererEvent<ResolvedAddress>>> eventPublisher,
             final ConnectionFactory<ResolvedAddress, T> connectionFactory) {
-        return useNewRoundRobin ? useNewRoundRobinLoadBalancer(targetResource, eventPublisher, connectionFactory)
-                                : new RoundRobinLoadBalancer<>(id, targetResource, eventPublisher, connectionFactory,
+        return new RoundRobinLoadBalancer<>(id, targetResource, eventPublisher, connectionFactory,
                 linearSearchSpace, healthCheckConfig);
     }
 
-    @Override
-    public LoadBalancer<C> newLoadBalancer(
-            final Publisher<? extends Collection<? extends ServiceDiscovererEvent<ResolvedAddress>>> eventPublisher,
-            final ConnectionFactory<ResolvedAddress, C> connectionFactory,
-            final String targetResource) {
-        return useNewRoundRobin ? useNewRoundRobinLoadBalancer(targetResource, eventPublisher, connectionFactory)
-                                : new RoundRobinLoadBalancer<>(id, targetResource, eventPublisher, connectionFactory,
-                linearSearchSpace, healthCheckConfig);
-    }
-
-    private <T extends C> LoadBalancer<T> useNewRoundRobinLoadBalancer(
-            final String targetResource,
-            final Publisher<? extends Collection<? extends ServiceDiscovererEvent<ResolvedAddress>>> eventPublisher,
-            final ConnectionFactory<ResolvedAddress, T> connectionFactory) {
-        return new DefaultLoadBalancer<>(id, targetResource, eventPublisher,
-                new RoundRobinSelector<>(Collections.emptyList(), targetResource, false), connectionFactory,
-                linearSearchSpace, NoopLoadBalancerObserver.instance(), healthCheckConfig, null);
-    }
-
     @Override
     public ExecutionStrategy requiredOffloads() {
         // We do not block
@@ -121,7 +97,6 @@ public static final class Builder<ResolvedAddress, C extends LoadBalancedConnect
             implements RoundRobinLoadBalancerBuilder<ResolvedAddress, C> {
         private final String id;
         private int linearSearchSpace = 16;
-        private boolean useNewRoundRobin;
         @Nullable
         private Executor backgroundExecutor;
         private Duration healthCheckInterval = DEFAULT_HEALTH_CHECK_INTERVAL;
@@ -153,13 +128,6 @@ public RoundRobinLoadBalancerFactory.Builder<ResolvedAddress, C> linearSearchSpa
             return this;
         }
 
-        // In the future we may elevate this to the RoundRobinLoadBalancerBuilder interface or pick another
-        // route to transition to the new load balancer structure.
-        RoundRobinLoadBalancerBuilder<ResolvedAddress, C> useNewRoundRobin(boolean useNewRoundRobin) {
-            this.useNewRoundRobin = useNewRoundRobin;
-            return this;
-        }
-
         @Override
         public RoundRobinLoadBalancerFactory.Builder<ResolvedAddress, C> backgroundExecutor(
                 Executor backgroundExecutor) {
@@ -217,14 +185,14 @@ public RoundRobinLoadBalancerFactory.Builder<ResolvedAddress, C> healthCheckFail
         @Override
         public RoundRobinLoadBalancerFactory<ResolvedAddress, C> build() {
             if (this.healthCheckFailedConnectionsThreshold < 0) {
-                return new RoundRobinLoadBalancerFactory<>(id, linearSearchSpace, useNewRoundRobin, null);
+                return new RoundRobinLoadBalancerFactory<>(id, linearSearchSpace, null);
             }
 
             HealthCheckConfig healthCheckConfig = new HealthCheckConfig(
                             this.backgroundExecutor == null ? SharedExecutor.getInstance() : this.backgroundExecutor,
                     healthCheckInterval, healthCheckJitter, healthCheckFailedConnectionsThreshold,
                     healthCheckResubscribeInterval, healthCheckResubscribeJitter);
-            return new RoundRobinLoadBalancerFactory<>(id, linearSearchSpace, useNewRoundRobin, healthCheckConfig);
+            return new RoundRobinLoadBalancerFactory<>(id, linearSearchSpace, healthCheckConfig);
         }
     }
 

settings.gradle

@@ -86,6 +86,7 @@ include "servicetalk-annotations",
         "servicetalk-http-security-jersey",
         "servicetalk-http-utils",
         "servicetalk-loadbalancer",
+        "servicetalk-loadbalancer-experimental",
         "servicetalk-log4j2-mdc",
         "servicetalk-log4j2-mdc-utils",
         "servicetalk-logging-api",