okhttp: Add OkHttpServerProvider

This allows okhttp to service the Grpc.newServerBuilderForPort() API.
Note that, unlike Netty, it will throw if you try to use
ServerBuilder.forPort().

This fixes android-interop-testing which was broken by c9864a119.

api/src/main/java/io/grpc/ServerRegistry.java

@@ -23,6 +23,7 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.logging.Level;
 import java.util.logging.Logger;
 import javax.annotation.concurrent.GuardedBy;
 import javax.annotation.concurrent.ThreadSafe;
@@ -92,7 +93,7 @@ public final class ServerRegistry {
     if (instance == null) {
       List<ServerProvider> providerList = ServiceProviders.loadAll(
           ServerProvider.class,
-          Collections.<Class<?>>emptyList(),
+          getHardCodedClasses(),
           ServerProvider.class.getClassLoader(),
           new ServerPriorityAccessor());
       instance = new ServerRegistry();
@@ -119,6 +120,20 @@ public final class ServerRegistry {
     return providers.isEmpty() ? null : providers.get(0);
   }
 
+  @VisibleForTesting
+  static List<Class<?>> getHardCodedClasses() {
+    // Class.forName(String) is used to remove the need for ProGuard configuration. Note that
+    // ProGuard does not detect usages of Class.forName(String, boolean, ClassLoader):
+    // https://sourceforge.net/p/proguard/bugs/418/
+    List<Class<?>> list = new ArrayList<>();
+    try {
+      list.add(Class.forName("io.grpc.okhttp.OkHttpServerProvider"));
+    } catch (ClassNotFoundException e) {
+      logger.log(Level.FINE, "Unable to find OkHttpServerProvider", e);
+    }
+    return Collections.unmodifiableList(list);
+  }
+
   ServerBuilder<?> newServerBuilderForPort(int port, ServerCredentials creds) {
     List<ServerProvider> providers = providers();
     if (providers.isEmpty()) {

api/src/testFixtures/java/io/grpc/ServerRegistryAccessor.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2023 The gRPC 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.grpc;
+
+/** Accesses test-only methods of {@link ServerRegistry}. */
+public final class ServerRegistryAccessor {
+  private ServerRegistryAccessor() {}
+
+  public static Iterable<Class<?>> getHardCodedClasses() {
+    return ServerRegistry.getHardCodedClasses();
+  }
+}

okhttp/build.gradle

@@ -50,6 +50,7 @@ tasks.named("checkstyleMain").configure {
 tasks.named("javadoc").configure {
     options.links 'http://square.github.io/okhttp/2.x/okhttp/'
     exclude 'io/grpc/okhttp/Internal*'
+    exclude 'io/grpc/okhttp/*Provider.java'
     exclude 'io/grpc/okhttp/internal/**'
 }
 

okhttp/src/main/java/io/grpc/okhttp/OkHttpServerBuilder.java

@@ -18,7 +18,6 @@ package io.grpc.okhttp;
 
 import static com.google.common.base.Preconditions.checkArgument;
 
-import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.DoNotCall;
@@ -89,7 +88,7 @@ public final class OkHttpServerBuilder extends ForwardingServerBuilder<OkHttpSer
   @DoNotCall("Always throws. Use forPort(int, ServerCredentials) instead")
   @Deprecated
   public static OkHttpServerBuilder forPort(int port) {
-    throw new UnsupportedOperationException();
+    throw new UnsupportedOperationException("Use forPort(int, ServerCredentials) instead");
   }
 
   /**
@@ -131,7 +130,6 @@ public final class OkHttpServerBuilder extends ForwardingServerBuilder<OkHttpSer
   long maxConnectionAgeInNanos = MAX_CONNECTION_AGE_NANOS_DISABLED;
   long maxConnectionAgeGraceInNanos = MAX_CONNECTION_AGE_GRACE_NANOS_INFINITE;
 
-  @VisibleForTesting
   OkHttpServerBuilder(
       SocketAddress address, HandshakerSocketFactory handshakerSocketFactory) {
     this.listenAddress = Preconditions.checkNotNull(address, "address");

okhttp/src/main/java/io/grpc/okhttp/OkHttpServerProvider.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2023 The gRPC 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.grpc.okhttp;
+
+import io.grpc.Internal;
+import io.grpc.ServerCredentials;
+import io.grpc.ServerProvider;
+import java.net.InetSocketAddress;
+
+/** Provider for {@link OkHttpServerBuilder} instances. */
+@Internal
+public final class OkHttpServerProvider extends ServerProvider {
+
+  @Override
+  protected boolean isAvailable() {
+    return true;
+  }
+
+  @Override
+  protected int priority() {
+    // Use a priority less than Netty since builderForPort() always throws.
+    return 4;
+  }
+
+  @Override
+  protected OkHttpServerBuilder builderForPort(int port) {
+    throw new UnsupportedOperationException("Use Grpc.newServerBuilderForPort() instead");
+  }
+
+  @Override
+  protected NewServerBuilderResult newServerBuilderForPort(int port, ServerCredentials creds) {
+    OkHttpServerBuilder.HandshakerSocketFactoryResult result =
+        OkHttpServerBuilder.handshakerSocketFactoryFrom(creds);
+    if (result.error != null) {
+      return NewServerBuilderResult.error(result.error);
+    }
+    return NewServerBuilderResult.serverBuilder(
+        new OkHttpServerBuilder(new InetSocketAddress(port), result.factory));
+  }
+}
+

okhttp/src/main/resources/META-INF/services/io.grpc.ServerProvider

@@ -0,0 +1 @@
+io.grpc.okhttp.OkHttpServerProvider

okhttp/src/test/java/io/grpc/okhttp/OkHttpServerProviderTest.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2023 The gRPC 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.grpc.okhttp;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertThrows;
+
+import io.grpc.InsecureServerCredentials;
+import io.grpc.ServerCredentials;
+import io.grpc.ServerProvider;
+import io.grpc.ServerRegistryAccessor;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Unit tests for {@link OkHttpServerProvider}. */
+@RunWith(JUnit4.class)
+public class OkHttpServerProviderTest {
+  private OkHttpServerProvider provider = new OkHttpServerProvider();
+
+  @Test
+  public void provided() {
+    assertThat(ServerProvider.provider()).isInstanceOf(OkHttpServerProvider.class);
+  }
+
+  @Test
+  public void providedHardCoded() {
+    assertThat(ServerRegistryAccessor.getHardCodedClasses()).contains(OkHttpServerProvider.class);
+  }
+
+  @Test
+  public void basicMethods() {
+    assertThat(provider.isAvailable()).isTrue();
+    assertThat(provider.priority()).isEqualTo(4);
+  }
+
+  @Test
+  public void builderIsAOkHttpBuilder() {
+    assertThrows(UnsupportedOperationException.class, () -> provider.builderForPort(80));
+  }
+
+  @Test
+  public void newServerBuilderForPort_success() {
+    ServerProvider.NewServerBuilderResult result =
+        provider.newServerBuilderForPort(80, InsecureServerCredentials.create());
+    assertThat(result.getServerBuilder()).isInstanceOf(OkHttpServerBuilder.class);
+  }
+
+  @Test
+  public void newServerBuilderForPort_fail() {
+    ServerProvider.NewServerBuilderResult result = provider.newServerBuilderForPort(
+        80, new FakeServerCredentials());
+    assertThat(result.getError()).contains("FakeServerCredentials");
+  }
+
+  private static final class FakeServerCredentials extends ServerCredentials {}
+}