core: abstract channel builder to accept LoadBalancer2 (#2583)

If a LoadBalancer2 is passed in, the builder will create ManagedChannelImpl2 instead of ManagedChannelImpl. This allows us to test the LBv2 classes on a large scale.

benchmarks/src/main/java/io/grpc/benchmarks/driver/LoadClient.java

@@ -46,7 +46,6 @@ import io.grpc.benchmarks.proto.Control;
 import io.grpc.benchmarks.proto.Messages;
 import io.grpc.benchmarks.proto.Payloads;
 import io.grpc.benchmarks.proto.Stats;
-import io.grpc.internal.ManagedChannelImpl;
 import io.grpc.stub.ClientCalls;
 import io.grpc.stub.StreamObserver;
 import io.netty.buffer.ByteBuf;
@@ -96,7 +95,7 @@ class LoadClient {
     log.log(Level.INFO, "Client Config \n" + config.toString());
     this.config = config;
     // Create the channels
-    channels = new ManagedChannelImpl[config.getClientChannels()];
+    channels = new ManagedChannel[config.getClientChannels()];
     for (int i = 0; i < config.getClientChannels(); i++) {
       channels[i] =
           Utils.newClientChannel(

core/src/main/java/io/grpc/internal/AbstractManagedChannelImplBuilder.java

@@ -46,6 +46,8 @@ import io.grpc.CompressorRegistry;
 import io.grpc.DecompressorRegistry;
 import io.grpc.Internal;
 import io.grpc.LoadBalancer;
+import io.grpc.LoadBalancer2;
+import io.grpc.ManagedChannel;
 import io.grpc.ManagedChannelBuilder;
 import io.grpc.NameResolver;
 import io.grpc.NameResolverProvider;
@@ -94,6 +96,7 @@ public abstract class AbstractManagedChannelImplBuilder
 
   @Nullable
   private Executor executor;
+
   private final List<ClientInterceptor> interceptors = new ArrayList<ClientInterceptor>();
 
   private final String target;
@@ -113,6 +116,9 @@ public abstract class AbstractManagedChannelImplBuilder
   @Nullable
   private LoadBalancer.Factory loadBalancerFactory;
 
+  @Nullable
+  private LoadBalancer2.Factory loadBalancer2Factory;
+
   @Nullable
   private DecompressorRegistry decompressorRegistry;
 
@@ -204,6 +210,17 @@ public abstract class AbstractManagedChannelImplBuilder
     return thisT();
   }
 
+  /**
+   * DO NOT CALL THIS, as its argument type will soon be renamed.
+   */
+  public final T loadBalancerFactory(LoadBalancer2.Factory loadBalancerFactory) {
+    Preconditions.checkState(directServerAddress == null,
+        "directServerAddress is set (%s), which forbids the use of LoadBalancerFactory",
+        directServerAddress);
+    this.loadBalancer2Factory = loadBalancerFactory;
+    return thisT();
+  }
+
   @Override
   public final T decompressorRegistry(DecompressorRegistry registry) {
     this.decompressorRegistry = registry;
@@ -266,7 +283,7 @@ public abstract class AbstractManagedChannelImplBuilder
   }
 
   @Override
-  public ManagedChannelImpl build() {
+  public ManagedChannel build() {
     ClientTransportFactory transportFactory = buildTransportFactory();
     if (authorityOverride != null) {
       transportFactory = new AuthorityOverridingTransportFactory(
@@ -279,6 +296,24 @@ public abstract class AbstractManagedChannelImplBuilder
       // getResource(), then this shouldn't be a problem unless called on the UI thread.
       nameResolverFactory = NameResolverProvider.asFactory();
     }
+    if (loadBalancer2Factory != null) {
+      return new ManagedChannelImpl2(
+          target,
+          // TODO(carl-mastrangelo): Allow clients to pass this in
+          new ExponentialBackoffPolicy.Provider(),
+          nameResolverFactory,
+          getNameResolverParams(),
+          loadBalancer2Factory,
+          transportFactory,
+          firstNonNull(decompressorRegistry, DecompressorRegistry.getDefaultInstance()),
+          firstNonNull(compressorRegistry, CompressorRegistry.getDefaultInstance()),
+          SharedResourcePool.forResource(GrpcUtil.TIMER_SERVICE),
+          getExecutorPool(executor),
+          SharedResourcePool.forResource(GrpcUtil.SHARED_CHANNEL_EXECUTOR),
+          GrpcUtil.STOPWATCH_SUPPLIER, idleTimeoutMillis,
+          userAgent, interceptors, firstNonNull(statsFactory,
+              firstNonNull(Stats.getStatsContextFactory(), NoopStatsContextFactory.INSTANCE)));
+    } else {
       return new ManagedChannelImpl(
           target,
           // TODO(carl-mastrangelo): Allow clients to pass this in
@@ -294,6 +329,7 @@ public abstract class AbstractManagedChannelImplBuilder
           firstNonNull(statsFactory,
               firstNonNull(Stats.getStatsContextFactory(), NoopStatsContextFactory.INSTANCE)));
     }
+  }
 
   /**
    * Subclasses should override this method to provide the {@link ClientTransportFactory}
@@ -311,6 +347,24 @@ public abstract class AbstractManagedChannelImplBuilder
     return Attributes.EMPTY;
   }
 
+  private static ObjectPool<? extends Executor> getExecutorPool(final @Nullable Executor executor) {
+    if (executor != null) {
+      return new ObjectPool<Executor>() {
+        @Override
+        public Executor getObject() {
+          return executor;
+        }
+
+        @Override
+        public Executor returnObject(Object returned) {
+          return null;
+        }
+      };
+    } else {
+      return SharedResourcePool.forResource(GrpcUtil.SHARED_CHANNEL_EXECUTOR);
+    }
+  }
+
   private static class AuthorityOverridingTransportFactory implements ClientTransportFactory {
     final ClientTransportFactory factory;
     final String authorityOverride;

core/src/main/java/io/grpc/internal/SharedResourcePool.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2016, Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *    * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *    * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *
+ *    * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.grpc.internal;
+
+/**
+ * An ObjectPool backed by a {@link SharedResourceHolder.Resource}.
+ */
+public final class SharedResourcePool<T> implements ObjectPool<T> {
+  private final SharedResourceHolder.Resource<T> resource;
+
+  private SharedResourcePool(SharedResourceHolder.Resource<T> resource) {
+    this.resource = resource;
+  }
+
+  public static <T> SharedResourcePool<T> forResource(SharedResourceHolder.Resource<T> resource) {
+    return new SharedResourcePool<T>(resource);
+  }
+
+  @Override
+  public T getObject() {
+    return SharedResourceHolder.get(resource);
+  }
+
+  @Override
+  @SuppressWarnings("unchecked")
+  public T returnObject(Object object) {
+    SharedResourceHolder.release(resource, (T) object);
+    return null;
+  }
+}

interop-testing/src/test/java/io/grpc/testing/integration/CascadingTest.java

@@ -43,6 +43,7 @@ import com.google.common.util.concurrent.SettableFuture;
 import io.grpc.Context;
 import io.grpc.Context.CancellableContext;
 import io.grpc.Deadline;
+import io.grpc.ManagedChannel;
 import io.grpc.Metadata;
 import io.grpc.ServerCall;
 import io.grpc.ServerCallHandler;
@@ -52,7 +53,6 @@ import io.grpc.Status;
 import io.grpc.StatusRuntimeException;
 import io.grpc.inprocess.InProcessChannelBuilder;
 import io.grpc.inprocess.InProcessServerBuilder;
-import io.grpc.internal.ManagedChannelImpl;
 import io.grpc.internal.ServerImpl;
 import io.grpc.stub.ServerCallStreamObserver;
 import io.grpc.stub.StreamObserver;
@@ -84,7 +84,7 @@ public class CascadingTest {
 
   @Mock
   TestServiceGrpc.TestServiceImplBase service;
-  private ManagedChannelImpl channel;
+  private ManagedChannel channel;
   private ServerImpl server;
   private CountDownLatch observedCancellations;
   private CountDownLatch receivedCancellations;