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.logging;
  
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import org.apache.beam.model.fnexecution.v1.BeamFnApi;
  import org.apache.beam.model.fnexecution.v1.BeamFnApi.LogControl;
  import org.apache.beam.model.fnexecution.v1.BeamFnLoggingGrpc;
  import org.apache.beam.sdk.fn.server.FnService;
  import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.stub.StreamObserver;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableSet;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /** An implementation of the Beam Fn Logging Service over gRPC. */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  public class GrpcLoggingService extends BeamFnLoggingGrpc.BeamFnLoggingImplBase
      implements FnService {
    private static final Logger LOG = LoggerFactory.getLogger(GrpcLoggingService.class);
  
    public static GrpcLoggingService forWriter(LogWriter writer) {
      return new GrpcLoggingService(writer);
    }
  
    private final LogWriter logWriter;
    private final ConcurrentMap<InboundObserver, StreamObserver<LogControl>> connectedClients;
  
    private GrpcLoggingService(LogWriter logWriter) {
      this.logWriter = logWriter;
      connectedClients = new ConcurrentHashMap<>();
    }
  
    @Override
    public void close() throws Exception {
      Set<InboundObserver> remainingClients = ImmutableSet.copyOf(connectedClients.keySet());
      if (!remainingClients.isEmpty()) {
        LOG.info(
            "{} Beam Fn Logging clients still connected during shutdown.", remainingClients.size());
  
        // Signal server shutting down to all remaining connected clients.
        for (InboundObserver client : remainingClients) {
          // We remove these from the connected clients map to prevent a race between
          // this close method and the InboundObserver calling a terminal method on the
          // StreamObserver. If we removed it, then we are responsible for the terminal call.
          completeIfNotNull(connectedClients.remove(client));
        }
      }
    }
  
    @Override
    public StreamObserver<BeamFnApi.LogEntry.List> logging(
        StreamObserver<BeamFnApi.LogControl> outboundObserver) {
      LOG.info("Beam Fn Logging client connected.");
      InboundObserver inboundObserver = new InboundObserver();
      connectedClients.put(inboundObserver, outboundObserver);
      return inboundObserver;
    }
  
    private void completeIfNotNull(StreamObserver<BeamFnApi.LogControl> outboundObserver) {
      if (outboundObserver != null) {
        try {
          outboundObserver.onCompleted();
        } catch (RuntimeException ignored) {
          // Completing outbound observer failed, ignoring failure and continuing
          LOG.warn("Beam Fn Logging client failed to be complete.", ignored);
        }
      }
    }
  
    /**
     * An inbound {@link StreamObserver} that forwards incoming messages to the client logger.
     *
     * <p>Mutually hangs up on clients that have errored or completed.
     */
    private class InboundObserver implements StreamObserver<BeamFnApi.LogEntry.List> {
      @Override
      public void onNext(BeamFnApi.LogEntry.List value) {
        for (BeamFnApi.LogEntry logEntry : value.getLogEntriesList()) {
          logWriter.log(logEntry);
        }
      }
  
      @Override
      public void onError(Throwable t) {
        LOG.warn("Logging client failed unexpectedly.", t);
        // We remove these from the connected clients map to prevent a race between
        // the close method and this InboundObserver calling a terminal method on the
        // StreamObserver. If we removed it, then we are responsible for the terminal call.
        completeIfNotNull(connectedClients.remove(this));
      }
  
      @Override
      public void onCompleted() {
        LOG.info("Logging client hanged up.");
        // We remove these from the connected clients map to prevent a race between
        // the close method and this InboundObserver calling a terminal method on the
        // StreamObserver. If we removed it, then we are responsible for the terminal call.
        completeIfNotNull(connectedClients.remove(this));
      }
    }
  }
  