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.malhar.contrib.nifi;
  
  import java.io.IOException;
  import java.util.List;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.apex.malhar.lib.wal.WindowDataManager;
  import org.apache.nifi.remote.Transaction;
  import org.apache.nifi.remote.TransferDirection;
  import org.apache.nifi.remote.client.SiteToSiteClient;
  
  import com.datatorrent.api.Context;
  import com.datatorrent.common.util.BaseOperator;
  import com.datatorrent.netlet.util.DTThrowable;
  
  /**
   * This is the base implementation of a NiFi output operator.&nbsp;
   * A concrete operator should be created from this skeleton implementation.
   * <p>
   * <br>
   * Ports:<br>
   * <b>Input</b>: Can have any number of input ports<br>
   * <b>Output</b>: no output port<br>
   * <br>
   * Properties:<br>
   * None<br>
   * <br>
   * Compile time checks:<br>
   * None<br>
   * <br>
   * Run time checks:<br>
   * None<br>
   * <br>
   * Benchmarks:<br>
   * TBD<br>
   * <br>
   * </p>
   *
   * @displayName Abstract NiFi Output
   * @category Messaging
   * @tags output operator
   *
   *
   * @since 3.4.0
   */
  public abstract class AbstractNiFiOutputOperator<T> extends BaseOperator
  {
  
    private static final Logger LOGGER = LoggerFactory.getLogger(AbstractNiFiOutputOperator.class);
  
    protected final SiteToSiteClient.Builder siteToSiteBuilder;
    protected final NiFiDataPacketBuilder<T> dataPacketBuilder;
    protected final WindowDataManager windowDataManager;
  
    protected transient SiteToSiteClient client;
  
    private transient int operatorContextId;
    private transient long currentWindowId;
    private transient long largestRecoveryWindowId;
    protected transient boolean skipProcessingTuple = false;
  
    /**
     * @param siteToSiteBuilder the builder for a NiFi SiteToSiteClient
     * @param dataPacketBuilder a builder to produce NiFiDataPackets from incoming data
     * @param windowDataManager  a WindowDataManager to save and load state for windows of tuples
     */
    public AbstractNiFiOutputOperator(final SiteToSiteClient.Builder siteToSiteBuilder,
        final NiFiDataPacketBuilder<T> dataPacketBuilder, final WindowDataManager windowDataManager)
    {
      this.siteToSiteBuilder = siteToSiteBuilder;
      this.dataPacketBuilder = dataPacketBuilder;
      this.windowDataManager = windowDataManager;
    }
  
    @Override
    public void setup(Context.OperatorContext context)
    {
      this.client = siteToSiteBuilder.build();
      this.operatorContextId = context.getId();
      this.windowDataManager.setup(context);
    }
  
    @Override
    public void beginWindow(long windowId)
    {
      currentWindowId = windowId;
      largestRecoveryWindowId = windowDataManager.getLargestCompletedWindow();
  
      // if processing a window we've already seen, don't resend the tuples
      if (currentWindowId <= largestRecoveryWindowId) {
        skipProcessingTuple = true;
      } else {
        skipProcessingTuple = false;
      }
    }
  
    @Override
    public void endWindow()
    {
      // if replaying then nothing to do
      if (currentWindowId <= largestRecoveryWindowId) {
        return;
      }
  
      // if processing a new window then give sub-classes a chance to take action
      endNewWindow();
  
      // mark that we processed the window
      try {
        windowDataManager.save("processedWindow", currentWindowId);
      } catch (IOException e) {
        DTThrowable.rethrow(e);
      }
    }
  
    /**
     * Called in endWindow() to give sub-classes a chance to take action when processing a new window.
     *
     * If the current window is <= the largest recovery window, this method will never be called.
     */
    protected abstract void endNewWindow();
  
  
    @Override
    public void teardown()
    {
      LOGGER.debug("Tearing down operator...");
      windowDataManager.teardown();
      try {
        client.close();
      } catch (IOException e) {
        DTThrowable.rethrow(e);
      }
    }
  
    /**
     * Send the given batch of tuples to NiFi in a transaction, using the provided builder to
     * first convert each tuple into a NiFiDataPacket.
     *
     * @param tuples a list of tuples to process
     */
    protected void processTuples(List<T> tuples)
    {
      if (tuples == null || tuples.size() == 0) {
        return;
      }
  
      // create a transaction and send the data packets
      try {
        final Transaction transaction = client.createTransaction(TransferDirection.SEND);
        if (transaction == null) {
          throw new IllegalStateException("Unable to create a NiFi Transaction to send data");
        }
  
        // convert each tuple to a NiFiDataPacket using the provided builder
        for (T tuple : tuples) {
          NiFiDataPacket dp = dataPacketBuilder.createNiFiDataPacket(tuple);
          transaction.send(dp.getContent(), dp.getAttributes());
        }
  
        transaction.confirm();
        transaction.complete();
      } catch (IOException ioe) {
        DTThrowable.rethrow(ioe);
      }
  
    }
  
  }
  