loadbalancer: move DefaultLoadBalancer out of experimental (#3136)

Motivation:

We've had DefaultLoadBalancer running in place of round-robin for
some time and it looks good. It's time to move it into the main
package and prepare to remove RoundRobinLoadBalancer.

Modifications:

Move most of the contents of servicetalk-loadbalancer-experimental
to the servicetalk-loadbalancer package.

Author: bryce-anderson

servicetalk-loadbalancer-experimental/src/main/java/io/servicetalk/loadbalancer/RequestTracker.java servicetalk-client-api/src/main/java/io/servicetalk/client/api/RequestTracker.java

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package io.servicetalk.loadbalancer;
+package io.servicetalk.client.api;
 
 import io.servicetalk.context.api.ContextMap;
 

servicetalk-examples/docs/modules/ROOT/pages/http/index.adoc

@@ -19,7 +19,7 @@ apply from: "../../gradle/idea.gradle"
 dependencies {
   implementation project(":servicetalk-annotations")
   implementation project(":servicetalk-http-netty")
-  implementation project(":servicetalk-loadbalancer-experimental")
+  implementation project(":servicetalk-loadbalancer")
 
   runtimeOnly "org.apache.logging.log4j:log4j-slf4j-impl:$log4jVersion"
 }

servicetalk-examples/http/loadbalancer/build.gradle

@@ -36,7 +36,6 @@ dependencies {
   implementation project(":servicetalk-transport-netty-internal")
   implementation project(":servicetalk-utils-internal")
   implementation project(":servicetalk-concurrent-internal")
-  implementation project(":servicetalk-loadbalancer-experimental")
   implementation "org.slf4j:slf4j-api:$slf4jVersion"
   implementation "com.google.protobuf:protobuf-java"
 

servicetalk-grpc-netty/build.gradle

@@ -19,6 +19,7 @@
 import io.servicetalk.client.api.ConnectionFactory;
 import io.servicetalk.client.api.ConnectionFactoryFilter;
 import io.servicetalk.client.api.DelegatingConnectionFactory;
+import io.servicetalk.client.api.RequestTracker;
 import io.servicetalk.concurrent.api.Single;
 import io.servicetalk.context.api.ContextMap;
 import io.servicetalk.grpc.api.GrpcLifecycleObserver;
@@ -28,7 +29,6 @@
 import io.servicetalk.http.api.HttpRequestMetaData;
 import io.servicetalk.http.api.HttpResponseMetaData;
 import io.servicetalk.http.netty.HttpLifecycleObserverRequesterFilter;
-import io.servicetalk.loadbalancer.RequestTracker;
 import io.servicetalk.transport.api.ConnectionInfo;
 import io.servicetalk.transport.api.ExecutionStrategy;
 import io.servicetalk.transport.api.TransportObserver;
@@ -40,7 +40,7 @@
 import java.util.function.Function;
 import javax.annotation.Nullable;
 
-import static io.servicetalk.loadbalancer.RequestTracker.REQUEST_TRACKER_KEY;
+import static io.servicetalk.client.api.RequestTracker.REQUEST_TRACKER_KEY;
 
 final class GrpcRequestTracker {
 

servicetalk-grpc-netty/src/main/java/io/servicetalk/grpc/netty/GrpcRequestTracker.java

@@ -16,6 +16,7 @@
 package io.servicetalk.grpc.netty;
 
 import io.servicetalk.client.api.DelegatingConnectionFactory;
+import io.servicetalk.client.api.RequestTracker;
 import io.servicetalk.concurrent.api.Publisher;
 import io.servicetalk.concurrent.api.Single;
 import io.servicetalk.context.api.ContextMap;
@@ -25,7 +26,6 @@
 import io.servicetalk.grpc.api.GrpcStatusCode;
 import io.servicetalk.grpc.api.GrpcStatusException;
 import io.servicetalk.http.api.FilterableStreamingHttpConnection;
-import io.servicetalk.loadbalancer.RequestTracker;
 import io.servicetalk.transport.api.HostAndPort;
 import io.servicetalk.transport.api.ServerContext;
 import io.servicetalk.transport.api.TransportObserver;
@@ -40,7 +40,7 @@
 import java.util.concurrent.atomic.AtomicInteger;
 import javax.annotation.Nullable;
 
-import static io.servicetalk.loadbalancer.RequestTracker.REQUEST_TRACKER_KEY;
+import static io.servicetalk.client.api.RequestTracker.REQUEST_TRACKER_KEY;
 import static io.servicetalk.transport.netty.internal.AddressUtils.localAddress;
 import static io.servicetalk.transport.netty.internal.AddressUtils.serverHostAndPort;
 import static org.hamcrest.MatcherAssert.assertThat;

servicetalk-grpc-netty/src/test/java/io/servicetalk/grpc/netty/GrpcRequestTrackerTest.java

@@ -29,7 +29,6 @@ dependencies {
   implementation project(":servicetalk-dns-discovery-netty")
   implementation project(":servicetalk-http-utils")
   implementation project(":servicetalk-loadbalancer")
-  implementation project(":servicetalk-loadbalancer-experimental")
   implementation project(":servicetalk-loadbalancer-experimental-provider")
   implementation project(":servicetalk-logging-slf4j-internal")
   implementation project(":servicetalk-tcp-netty-internal")

servicetalk-http-netty/build.gradle

@@ -19,14 +19,14 @@
 import io.servicetalk.client.api.ConnectionFactory;
 import io.servicetalk.client.api.ConnectionFactoryFilter;
 import io.servicetalk.client.api.DelegatingConnectionFactory;
+import io.servicetalk.client.api.RequestTracker;
 import io.servicetalk.concurrent.api.Single;
 import io.servicetalk.context.api.ContextMap;
 import io.servicetalk.http.api.FilterableStreamingHttpConnection;
 import io.servicetalk.http.api.HttpHeaders;
 import io.servicetalk.http.api.HttpLifecycleObserver;
 import io.servicetalk.http.api.HttpRequestMetaData;
 import io.servicetalk.http.api.HttpResponseMetaData;
-import io.servicetalk.loadbalancer.RequestTracker;
 import io.servicetalk.transport.api.ConnectionInfo;
 import io.servicetalk.transport.api.ExecutionStrategy;
 import io.servicetalk.transport.api.TransportObserver;
@@ -38,11 +38,11 @@
 import java.util.concurrent.atomic.AtomicLongFieldUpdater;
 import javax.annotation.Nullable;
 
+import static io.servicetalk.client.api.RequestTracker.ErrorClass.EXT_ORIGIN_TIMEOUT;
+import static io.servicetalk.client.api.RequestTracker.ErrorClass.LOCAL_ORIGIN_REQUEST_FAILED;
+import static io.servicetalk.client.api.RequestTracker.REQUEST_TRACKER_KEY;
 import static io.servicetalk.http.api.HttpResponseStatus.StatusClass.SERVER_ERROR_5XX;
 import static io.servicetalk.http.api.HttpResponseStatus.TOO_MANY_REQUESTS;
-import static io.servicetalk.loadbalancer.RequestTracker.ErrorClass.EXT_ORIGIN_TIMEOUT;
-import static io.servicetalk.loadbalancer.RequestTracker.ErrorClass.LOCAL_ORIGIN_REQUEST_FAILED;
-import static io.servicetalk.loadbalancer.RequestTracker.REQUEST_TRACKER_KEY;
 
 final class HttpRequestTracker {
 

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

@@ -16,14 +16,14 @@
 package io.servicetalk.http.netty;
 
 import io.servicetalk.client.api.DelegatingConnectionFactory;
+import io.servicetalk.client.api.RequestTracker;
 import io.servicetalk.concurrent.api.Single;
 import io.servicetalk.context.api.ContextMap;
 import io.servicetalk.http.api.FilterableStreamingHttpConnection;
 import io.servicetalk.http.api.HttpClient;
 import io.servicetalk.http.api.HttpResponse;
 import io.servicetalk.http.api.HttpService;
 import io.servicetalk.http.api.SingleAddressHttpClientBuilder;
-import io.servicetalk.loadbalancer.RequestTracker;
 import io.servicetalk.transport.api.HostAndPort;
 import io.servicetalk.transport.api.ServerContext;
 import io.servicetalk.transport.api.TransportObserver;
@@ -39,7 +39,7 @@
 
 import static io.netty.handler.codec.http.HttpStatusClass.SERVER_ERROR;
 import static io.netty.handler.codec.http.HttpStatusClass.SUCCESS;
-import static io.servicetalk.loadbalancer.RequestTracker.REQUEST_TRACKER_KEY;
+import static io.servicetalk.client.api.RequestTracker.REQUEST_TRACKER_KEY;
 import static io.servicetalk.transport.netty.internal.AddressUtils.localAddress;
 import static io.servicetalk.transport.netty.internal.AddressUtils.serverHostAndPort;
 import static org.hamcrest.MatcherAssert.assertThat;

servicetalk-http-netty/src/test/java/io/servicetalk/http/netty/HttpRequestTrackerTest.java

@@ -21,6 +21,5 @@ dependencies {
 
   implementation project(":servicetalk-annotations")
   implementation project(":servicetalk-loadbalancer")
-  implementation project(":servicetalk-loadbalancer-experimental")
   implementation "org.slf4j:slf4j-api:$slf4jVersion"
 }

servicetalk-loadbalancer-experimental-provider/build.gradle

@@ -16,24 +16,9 @@
 
 apply plugin: "io.servicetalk.servicetalk-gradle-plugin-internal-library"
 
-dependencies {
-  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 "org.slf4j:slf4j-api:$slf4jVersion"
+tasks.named("javadoc").configure {
+    enabled = false
+}
 
-  testImplementation enforcedPlatform("org.junit:junit-bom:$junit5Version")
-  testImplementation testFixtures(project(":servicetalk-concurrent-api"))
-  testImplementation testFixtures(project(":servicetalk-concurrent-internal"))
-  testImplementation project(":servicetalk-concurrent-test-internal")
-  testImplementation project(":servicetalk-test-resources")
-  testImplementation "org.junit.jupiter:junit-jupiter-api"
-  testImplementation "org.junit.jupiter:junit-jupiter-params"
-  testImplementation "org.hamcrest:hamcrest:$hamcrestVersion"
-  testImplementation "org.mockito:mockito-core:$mockitoCoreVersion"
+dependencies {
 }

servicetalk-loadbalancer-experimental/build.gradle

@@ -1,7 +1,4 @@
 # This is a Gradle generated file for dependency locking.
 # Manual edits can break the build and are not advised.
 # This file is expected to be part of source control.
-com.google.code.findbugs:jsr305:3.0.2=compileClasspath,runtimeClasspath
-org.jctools:jctools-core:4.0.3=runtimeClasspath
-org.slf4j:slf4j-api:1.7.36=compileClasspath,runtimeClasspath
-empty=annotationProcessor,spotbugsPlugins,testAnnotationProcessor
+empty=annotationProcessor,compileClasspath,runtimeClasspath

servicetalk-loadbalancer-experimental/gradle.lockfile

@@ -21,8 +21,4 @@
 <suppressions>
     <!-- No need for package-info.java file because we reuse the package where this file already exists -->
     <suppress checks="JavadocPackage" files=".*[\\/]src[\\/]main[\\/]java[\\/]io[\\/]servicetalk[\\/]loadbalancer.*"/>
-    <suppress id="MissedElementsAreNonnullByDefault"
-              files="io[\\/]servicetalk[\\/]loadbalancer[\\/]package-info.java"/>
-    <suppress checks="LineLength"
-              files="io[\\/]servicetalk[\\/]loadbalancer[\\/]OutlierDetectorConfig.java"/>
 </suppressions>

servicetalk-loadbalancer-experimental/gradle/checkstyle/suppressions.xml

@@ -0,0 +1,23 @@
+/*
+ * Copyright © 2024 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;
+
+// FIXME: 0.43: TL;DR: Remove this module. This package existed to support the DefaultLoadBalancer development which
+//  has since been merged into the servicetalk-loadbalancer module.
+final class PlaceHolder {
+    private PlaceHolder() {
+    }
+}

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

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright © 2024 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.
+  -->
+<!DOCTYPE suppressions PUBLIC
+        "-//Checkstyle//DTD SuppressionFilter Configuration 1.2//EN"
+        "https://checkstyle.org/dtds/suppressions_1_2.dtd">
+
+<suppressions>
+    <suppress checks="LineLength"
+              files="io[\\/]servicetalk[\\/]loadbalancer[\\/]OutlierDetectorConfig.java"/>
+</suppressions>

servicetalk-loadbalancer-experimental/src/main/java/io/servicetalk/loadbalancer/PlaceHolder.java

@@ -15,6 +15,8 @@
  */
 package io.servicetalk.loadbalancer;
 
+import io.servicetalk.client.api.RequestTracker;
+
 /**
  * An interface for tracking connection establishment measurements.
  * This has an intended usage similar to the {@link RequestTracker} but with a focus on connection establishment

servicetalk-loadbalancer-experimental/README.adoc servicetalk-loadbalancer/DEFAULTLOADBALANCER.adoc

@@ -42,6 +42,7 @@
 import java.util.function.Predicate;
 import javax.annotation.Nullable;
 
+import static io.servicetalk.client.api.RequestTracker.REQUEST_TRACKER_KEY;
 import static io.servicetalk.concurrent.api.AsyncCloseables.toAsyncCloseable;
 import static io.servicetalk.concurrent.api.Completable.completed;
 import static io.servicetalk.concurrent.api.Publisher.fromIterable;
@@ -52,7 +53,6 @@
 import static io.servicetalk.loadbalancer.ConnectTracker.ErrorClass.CANCELLED;
 import static io.servicetalk.loadbalancer.ConnectTracker.ErrorClass.CONNECT_ERROR;
 import static io.servicetalk.loadbalancer.ConnectTracker.ErrorClass.CONNECT_TIMEOUT;
-import static io.servicetalk.loadbalancer.RequestTracker.REQUEST_TRACKER_KEY;
 import static java.util.Collections.emptyList;
 import static java.util.Objects.requireNonNull;
 import static java.util.concurrent.atomic.AtomicReferenceFieldUpdater.newUpdater;

servicetalk-loadbalancer/gradle/checkstyle/suppressions.xml

@@ -15,6 +15,7 @@
  */
 package io.servicetalk.loadbalancer;
 
+import io.servicetalk.client.api.RequestTracker;
 import io.servicetalk.client.api.ScoreSupplier;
 
 import java.util.concurrent.locks.StampedLock;

servicetalk-loadbalancer-experimental/license/LICENSE.grpc-java.txt servicetalk-loadbalancer/license/LICENSE.grpc-java.txt

@@ -16,6 +16,7 @@
 package io.servicetalk.loadbalancer;
 
 import io.servicetalk.client.api.LoadBalancedConnection;
+import io.servicetalk.client.api.RequestTracker;
 import io.servicetalk.client.api.ScoreSupplier;
 import io.servicetalk.concurrent.Cancellable;
 

servicetalk-loadbalancer-experimental/src/main/java/io/servicetalk/loadbalancer/BaseHostSelector.java servicetalk-loadbalancer/src/main/java/io/servicetalk/loadbalancer/BaseHostSelector.java

@@ -16,6 +16,7 @@
 package io.servicetalk.loadbalancer;
 
 import io.servicetalk.client.api.LoadBalancedConnection;
+import io.servicetalk.client.api.RequestTracker;
 import io.servicetalk.concurrent.api.Executor;
 import io.servicetalk.loadbalancer.LoadBalancerObserver.HostObserver;
 

servicetalk-loadbalancer-experimental/src/main/java/io/servicetalk/loadbalancer/CatchAllLoadBalancerObserver.java servicetalk-loadbalancer/src/main/java/io/servicetalk/loadbalancer/CatchAllLoadBalancerObserver.java

@@ -15,6 +15,7 @@
  */
 package io.servicetalk.loadbalancer;
 
+import io.servicetalk.client.api.RequestTracker;
 import io.servicetalk.client.api.ServiceDiscovererEvent;
 import io.servicetalk.concurrent.PublisherSource;
 import io.servicetalk.concurrent.api.Processors;

servicetalk-loadbalancer-experimental/src/main/java/io/servicetalk/loadbalancer/ConnectTracker.java servicetalk-loadbalancer/src/main/java/io/servicetalk/loadbalancer/ConnectTracker.java

@@ -15,6 +15,8 @@
  */
 package io.servicetalk.loadbalancer;
 
+import io.servicetalk.client.api.RequestTracker;
+
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;