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.apex.examples.kafka.exactlyonceoutput;
  
  import java.io.IOException;
  
  import javax.validation.constraints.NotNull;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  
  import com.datatorrent.api.Context;
  import com.datatorrent.api.DefaultInputPort;
  import com.datatorrent.api.DefaultOutputPort;
  import com.datatorrent.common.util.BaseOperator;
  
  /**
   * To produce an exactly-once scenario the PassthroughFailOperator kills itself after a certain number
   * of processed lines by throwing an exception. YARN will deploy the Operator in a new container,
   * hence not checkpointed tuples will be passed to the OutputOperators more than once.
   *
   * @since 3.8.0
   */
  public class PassthroughFailOperator extends BaseOperator
  {
    private static final Logger LOG = LoggerFactory.getLogger(PassthroughFailOperator.class);
    private boolean killed;
  
    @NotNull
    private int tuplesUntilKill;
  
    //start with empty windows to ensure tests run reliable
    private int emptyWindowsCount = 0;
  
    @NotNull
    private String directoryPath;
  
    private String filePath;
    private transient FileSystem hdfs;
    private transient Path filePathObj;
  
    public final transient DefaultOutputPort<String> output = new DefaultOutputPort<>();
  
    /**
     * Loads file from HDFS and sets {@link #killed} flag if it already exists
     *
     * @param context
     */
    @Override
    public void setup(Context.OperatorContext context)
    {
      super.setup(context);
      String appId = context.getValue(Context.DAGContext.APPLICATION_ID);
      filePath = directoryPath + "/" + appId;
  
      LOG.info("FilePath: " + filePath);
      filePathObj = new Path(filePath);
      try {
        hdfs = FileSystem.newInstance(filePathObj.toUri(), new Configuration());
      } catch (IOException e) {
        e.printStackTrace();
      }
  
      try {
        if (hdfs.exists(filePathObj)) {
          killed = true;
          LOG.info("file already exists -> Operator has been killed before");
        }
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
  
    @Override
    public void beginWindow(long windowId)
    {
      super.beginWindow(windowId);
      LOG.debug("WindowId: " + windowId);
      ++emptyWindowsCount;
    }
  
    public final transient DefaultInputPort<String> input = new DefaultInputPort<String>()
    {
      /**
       * Creates file on HDFS identified by ApplicationId to save killed state, if operator has not been killed yet.
       * Throws Exception to kill operator.
       *
       * @param line
       */
      @Override
      public void process(String line)
      {
        if (emptyWindowsCount > 3) {
          LOG.debug("LINE " + line);
          if (killed) {
            output.emit(line);
          } else if (tuplesUntilKill > 0) {
            output.emit(line);
            tuplesUntilKill--;
          } else {
            try {
              hdfs.createNewFile(filePathObj);
              LOG.info("Created file " + filePath);
            } catch (IOException e) {
              e.printStackTrace();
            }
            //kill operator
            LOG.info("Operator intentionally killed through exception");
            RuntimeException e = new RuntimeException("Exception to intentionally kill operator");
            throw e;
          }
        }
      }
    };
  
    public String getDirectoryPath()
    {
      return directoryPath;
    }
  
    public void setDirectoryPath(String directoryPath)
    {
      this.directoryPath = directoryPath;
    }
  
    public int getTuplesUntilKill()
    {
      return tuplesUntilKill;
    }
  
    public void setTuplesUntilKill(int tuplesUntilKill)
    {
      this.tuplesUntilKill = tuplesUntilKill;
    }
  
  }
  
  