content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 org.apache.beam.sdk.fn.server;
  
  import java.io.IOException;
  import java.util.Collections;
  import java.util.List;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicInteger;
  import org.apache.beam.model.pipeline.v1.Endpoints.ApiServiceDescriptor;
  import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.Server;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableList;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Lists;
  
  /**
   * A {@link Server gRPC Server} which manages a single {@link FnService}. The lifetime of the
   * service is bound to the {@link GrpcFnServer}.
   */
  @SuppressWarnings({
    "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
    "nullness",
    "keyfor"
  }) // TODO(https://github.com/apache/beam/issues/20497)
  public class GrpcFnServer<ServiceT extends FnService> implements AutoCloseable {
    /**
     * Create a {@link GrpcFnServer} for the provided {@link FnService} running on an arbitrary port.
     */
    public static <ServiceT extends FnService> GrpcFnServer<ServiceT> allocatePortAndCreateFor(
        ServiceT service, ServerFactory factory) throws IOException {
      ApiServiceDescriptor.Builder apiServiceDescriptor = ApiServiceDescriptor.newBuilder();
      Server server =
          factory.allocateAddressAndCreate(ImmutableList.of(service), apiServiceDescriptor);
      return new GrpcFnServer<>(server, service, apiServiceDescriptor.build());
    }
  
    /**
     * Create {@link GrpcFnServer}s for the provided {@link FnService}s running on an arbitrary port.
     */
    public static List<GrpcFnServer<? extends FnService>> allocatePortAndCreateFor(
        List<? extends FnService> services, ServerFactory factory) throws IOException {
      ApiServiceDescriptor.Builder apiServiceDescriptor = ApiServiceDescriptor.newBuilder();
      Server server =
          factory.allocateAddressAndCreate(
              Collections.unmodifiableList(services), apiServiceDescriptor);
      AtomicInteger countdown = new AtomicInteger(services.size());
      return Lists.transform(
          services,
          service ->
              new SharedGrpcFnServer<>(server, service, apiServiceDescriptor.build(), countdown));
    }
  
    /**
     * Create {@link GrpcFnServer}s for the provided {@link FnService}s running on a specified port.
     */
    public static List<GrpcFnServer<? extends FnService>> create(
        List<? extends FnService> services, ApiServiceDescriptor endpoint, ServerFactory factory)
        throws IOException {
      Server server = factory.create(Collections.unmodifiableList(services), endpoint);
      AtomicInteger countdown = new AtomicInteger(services.size());
      return Lists.transform(
          services, service -> new SharedGrpcFnServer<>(server, service, endpoint, countdown));
    }
  
    private static class SharedGrpcFnServer<ServiceT extends FnService>
        extends GrpcFnServer<ServiceT> {
  
      private AtomicInteger countdown;
  
      private SharedGrpcFnServer(
          Server server,
          ServiceT service,
          ApiServiceDescriptor apiServiceDescriptor,
          AtomicInteger countdown) {
        super(server, service, apiServiceDescriptor);
        this.countdown = countdown;
      }
  
      @Override
      public void close() throws Exception {
        if (countdown.addAndGet(-1) == 0) {
          super.close();
        } else {
          getService().close();
        }
      }
    }
  
    /**
     * Create a {@link GrpcFnServer} for the provided {@link FnService} which will run at the endpoint
     * specified in the {@link ApiServiceDescriptor}.
     */
    public static <ServiceT extends FnService> GrpcFnServer<ServiceT> create(
        ServiceT service, ApiServiceDescriptor endpoint, ServerFactory factory) throws IOException {
      return new GrpcFnServer<>(
          factory.create(ImmutableList.of(service), endpoint), service, endpoint);
    }
  
    /** @deprecated This create function is used for Dataflow migration purpose only. */
    @Deprecated
    public static <ServiceT extends FnService> GrpcFnServer<ServiceT> create(
        ServiceT service, ApiServiceDescriptor endpoint) {
      return new GrpcFnServer(null, service, endpoint) {
        @Override
        public void close() throws Exception {}
      };
    }
  
    private final Server server;
    private final ServiceT service;
    private final ApiServiceDescriptor apiServiceDescriptor;
  
    private GrpcFnServer(Server server, ServiceT service, ApiServiceDescriptor apiServiceDescriptor) {
      this.server = server;
      this.service = service;
      this.apiServiceDescriptor = apiServiceDescriptor;
    }
  
    /**
     * Get an {@link ApiServiceDescriptor} describing the endpoint this {@link GrpcFnServer} is bound
     * to.
     */
    public ApiServiceDescriptor getApiServiceDescriptor() {
      return apiServiceDescriptor;
    }
  
    /** Get the service exposed by this {@link GrpcFnServer}. */
    public ServiceT getService() {
      return service;
    }
  
    /** Get the underlying {@link Server} contained by this {@link GrpcFnServer}. */
    public Server getServer() {
      return server;
    }
  
    @Override
    public void close() throws Exception {
      try {
        // The server has been closed, and should not respond to any new incoming calls.
        server.shutdown();
        service.close();
        server.awaitTermination(60, TimeUnit.SECONDS);
      } finally {
        server.shutdownNow();
        server.awaitTermination();
      }
    }
  }
  