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.flink.streaming.connectors.akka;
  
  import akka.actor.ActorRef;
  import akka.actor.ActorSystem;
  import akka.actor.PoisonPill;
  import akka.actor.Props;
  import com.typesafe.config.Config;
  import com.typesafe.config.ConfigValueFactory;
  import org.apache.flink.configuration.Configuration;
  import org.apache.flink.streaming.api.functions.source.RichSourceFunction;
  import org.apache.flink.streaming.api.functions.source.SourceFunction;
  import org.apache.flink.streaming.connectors.akka.utils.ReceiverActor;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import scala.concurrent.Await;
  import scala.concurrent.duration.Duration;
  
  import java.util.Collections;
  
  /**
   * Implementation of {@link SourceFunction} specialized to read messages
   * from Akka actors.
   */
  public class AkkaSource extends RichSourceFunction<Object> {
  
    private static final Logger LOG = LoggerFactory.getLogger(AkkaSource.class);
  
    private static final long serialVersionUID = 1L;
  
    // --- Fields set by the constructor
  
    private final Class<?> classForActor;
  
    private final String actorName;
  
    private final String urlOfPublisher;
  
    private final Config configuration;
  
    // --- Runtime fields
    private transient ActorSystem receiverActorSystem;
    private transient ActorRef receiverActor;
  
    protected transient boolean autoAck;
  
    /**
     * Creates {@link AkkaSource} for Streaming
     *
     * @param actorName Receiver Actor name
     * @param urlOfPublisher tcp url of the publisher or feeder actor
     */
    public AkkaSource(String actorName,
            String urlOfPublisher,
            Config configuration) {
      super();
      this.classForActor = ReceiverActor.class;
      this.actorName = actorName;
      this.urlOfPublisher = urlOfPublisher;
      this.configuration = configuration;
    }
  
    @Override
    public void open(Configuration parameters) throws Exception {
      receiverActorSystem = createDefaultActorSystem();
  
      if (configuration.hasPath("akka.remote.auto-ack") &&
        configuration.getString("akka.remote.auto-ack").equals("on")) {
        autoAck = true;
      } else {
        autoAck = false;
      }
    }
  
    @Override
    public void run(SourceFunction.SourceContext<Object> ctx) throws Exception {
      LOG.info("Starting the Receiver actor {}", actorName);
      receiverActor = receiverActorSystem.actorOf(
        Props.create(classForActor, ctx, urlOfPublisher, autoAck), actorName);
  
      LOG.info("Started the Receiver actor {} successfully", actorName);
      Await.result(receiverActorSystem.whenTerminated(), Duration.Inf());
    }
  
    @Override
    public void close() {
      LOG.info("Closing source");
      if (receiverActorSystem != null) {
        receiverActor.tell(PoisonPill.getInstance(), ActorRef.noSender());
        receiverActorSystem.terminate();
      }
    }
  
    @Override
    public void cancel() {
      LOG.info("Cancelling akka source");
      close();
    }
  
    /**
     * Creates an actor system with default configurations for Receiver actor.
     *
     * @return Actor System instance with default configurations
     */
    private ActorSystem createDefaultActorSystem() {
      String defaultActorSystemName = "receiver-actor-system";
  
      Config finalConfig = getOrCreateMandatoryProperties(configuration);
  
      return ActorSystem.create(defaultActorSystemName, finalConfig);
    }
  
    private Config getOrCreateMandatoryProperties(Config properties) {
      if (!properties.hasPath("akka.actor.provider")) {
        properties = properties.withValue("akka.actor.provider",
          ConfigValueFactory.fromAnyRef("akka.remote.RemoteActorRefProvider"));
      }
  
      if (!properties.hasPath("akka.remote.enabled-transports")) {
        properties = properties.withValue("akka.remote.enabled-transports",
          ConfigValueFactory.fromAnyRef(Collections.singletonList("akka.remote.netty.tcp")));
      }
      return properties;
    }
  }
  