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.runners.fnexecution.data;
  
  import java.util.Queue;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.LinkedBlockingQueue;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.TimeoutException;
  import java.util.function.Supplier;
  import org.apache.beam.model.fnexecution.v1.BeamFnApi;
  import org.apache.beam.model.fnexecution.v1.BeamFnApi.Elements;
  import org.apache.beam.model.fnexecution.v1.BeamFnDataGrpc;
  import org.apache.beam.sdk.fn.data.BeamFnDataGrpcMultiplexer;
  import org.apache.beam.sdk.fn.data.BeamFnDataOutboundAggregator;
  import org.apache.beam.sdk.fn.data.CloseableFnDataReceiver;
  import org.apache.beam.sdk.fn.server.FnService;
  import org.apache.beam.sdk.fn.stream.OutboundObserverFactory;
  import org.apache.beam.sdk.options.PipelineOptions;
  import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.stub.StreamObserver;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.util.concurrent.SettableFuture;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * A {@link FnDataService} implemented via gRPC.
   *
   * <p>This service allows for multiple clients to transmit {@link BeamFnApi.Elements} messages.
   *
   * <p>This service transmits all outgoing {@link BeamFnApi.Elements} messages to the first client
   * that connects.
   */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  public class GrpcDataService extends BeamFnDataGrpc.BeamFnDataImplBase
      implements FnService, FnDataService {
    private static final Logger LOG = LoggerFactory.getLogger(GrpcDataService.class);
  
    public static GrpcDataService create(
        PipelineOptions options,
        ExecutorService executor,
        OutboundObserverFactory outboundObserverFactory) {
      return new GrpcDataService(options, executor, outboundObserverFactory);
    }
  
    private final SettableFuture<BeamFnDataGrpcMultiplexer> connectedClient;
    /**
     * A collection of multiplexers which are not used to send data. A handle to these multiplexers is
     * maintained in order to perform an orderly shutdown.
     *
     * <p>TODO: (BEAM-3811) Replace with some cancellable collection, to ensure that new clients of a
     * closed {@link GrpcDataService} are closed with that {@link GrpcDataService}.
     */
    private final Queue<BeamFnDataGrpcMultiplexer> additionalMultiplexers;
  
    private final PipelineOptions options;
    private final ExecutorService executor;
    private final OutboundObserverFactory outboundObserverFactory;
  
    private GrpcDataService(
        PipelineOptions options,
        ExecutorService executor,
        OutboundObserverFactory outboundObserverFactory) {
      this.connectedClient = SettableFuture.create();
      this.additionalMultiplexers = new LinkedBlockingQueue<>();
      this.options = options;
      this.executor = executor;
      this.outboundObserverFactory = outboundObserverFactory;
    }
  
    /** @deprecated This constructor is for migrating Dataflow purpose only. */
    @Deprecated
    public GrpcDataService() {
      this.connectedClient = null;
      this.additionalMultiplexers = null;
      this.options = null;
      this.executor = null;
      this.outboundObserverFactory = null;
    }
  
    @Override
    public StreamObserver<BeamFnApi.Elements> data(
        final StreamObserver<BeamFnApi.Elements> outboundElementObserver) {
      LOG.info("Beam Fn Data client connected.");
      BeamFnDataGrpcMultiplexer multiplexer =
          new BeamFnDataGrpcMultiplexer(
              null, outboundObserverFactory, inbound -> outboundElementObserver);
      // First client that connects completes this future.
      if (!connectedClient.set(multiplexer)) {
        additionalMultiplexers.offer(multiplexer);
      }
      try {
        // We specifically return the connected clients inbound observer so that all
        // incoming messages are sent to the single multiplexer instance.
        return connectedClient.get().getInboundObserver();
      } catch (InterruptedException | ExecutionException e) {
        throw new RuntimeException(e);
      }
    }
  
    @Override
    public void close() throws Exception {
      // Cancel anything blocking on a client connecting to this service. This doesn't shut down the
      // Multiplexer, but if there isn't any multiplexer it prevents callers blocking forever.
      connectedClient.cancel(true);
      // Close any other open connections
      for (BeamFnDataGrpcMultiplexer additional : additionalMultiplexers) {
        try {
          additional.close();
        } catch (Exception ignored) {
          // Shutdown remaining clients
        }
      }
      if (!connectedClient.isCancelled()) {
        connectedClient.get().close();
      }
    }
  
    @Override
    @SuppressWarnings("FutureReturnValueIgnored")
    public void registerReceiver(String instructionId, CloseableFnDataReceiver<Elements> observer) {
      LOG.debug("Registering observer for instruction {}", instructionId);
      if (connectedClient.isDone()) {
        try {
          connectedClient.get().registerConsumer(instructionId, observer);
        } catch (InterruptedException e) {
          Thread.currentThread().interrupt();
          throw new RuntimeException(e);
        } catch (ExecutionException e) {
          throw new RuntimeException(e.getCause());
        }
      } else {
        executor.submit(
            () -> {
              try {
                connectedClient.get().registerConsumer(instructionId, observer);
              } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                throw new RuntimeException(e);
              } catch (ExecutionException e) {
                throw new RuntimeException(e.getCause());
              }
            });
      }
    }
  
    @Override
    public void unregisterReceiver(String instructionId) {
      try {
        connectedClient.get().unregisterConsumer(instructionId);
      } catch (InterruptedException e) {
        Thread.currentThread().interrupt();
        throw new RuntimeException(e);
      } catch (ExecutionException e) {
        throw new RuntimeException(e.getCause());
      }
    }
  
    @Override
    public BeamFnDataOutboundAggregator createOutboundAggregator(
        Supplier<String> processBundleRequestIdSupplier, boolean collectElementsIfNoFlushes) {
      try {
        return new BeamFnDataOutboundAggregator(
            options,
            processBundleRequestIdSupplier,
            connectedClient.get(3, TimeUnit.MINUTES).getOutboundObserver(),
            collectElementsIfNoFlushes);
      } catch (InterruptedException e) {
        Thread.currentThread().interrupt();
        throw new RuntimeException(e);
      } catch (TimeoutException e) {
        throw new RuntimeException("No client connected within timeout", e);
      } catch (ExecutionException e) {
        throw new RuntimeException(e);
      }
    }
  }
  