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.carbondata.processing.loading;
  
  import java.io.IOException;
  import java.util.Iterator;
  import java.util.concurrent.atomic.AtomicLong;
  
  import org.apache.carbondata.common.logging.LogServiceFactory;
  import org.apache.carbondata.processing.index.IndexWriterListener;
  import org.apache.carbondata.processing.loading.exception.CarbonDataLoadingException;
  import org.apache.carbondata.processing.loading.row.CarbonRowBatch;
  
  import org.apache.log4j.Logger;
  
  /**
   * This base abstract class for data loading.
   * It can do transformation jobs as per the implementation.
   *
   * Life cycle of this class is
   * First initialize() is called to initialize the step
   * then execute() is called to process the step logic and
   * then close() is called to close any resources if any opened in the step.
   */
  public abstract class AbstractDataLoadProcessorStep {
  
    private static final Logger LOGGER =
        LogServiceFactory.getLogService(AbstractDataLoadProcessorStep.class.getName());
  
    protected CarbonDataLoadConfiguration configuration;
  
    protected AbstractDataLoadProcessorStep child;
  
    protected AtomicLong rowCounter;
  
    protected boolean closed;
  
    public AbstractDataLoadProcessorStep(CarbonDataLoadConfiguration configuration,
        AbstractDataLoadProcessorStep child) {
      this.configuration = configuration;
      this.child = child;
      this.rowCounter = new AtomicLong();
      this.closed = false;
    }
  
    /**
     * The output meta for this step. The data returns from this step is as per this meta.
     *
     */
    public DataField[] getOutput() {
      return child.getOutput();
    }
  
    /**
     * Initialization process for this step.
     *
     * @throws IOException
     */
    public void initialize() throws IOException {
      if (LOGGER.isDebugEnabled()) {
        // This thread prints the rows processed in each step for every 10 seconds.
        new Thread() {
          @Override
          public void run() {
            while (!closed) {
              try {
                LOGGER.debug("Rows processed in step " + getStepName() + " : " + rowCounter.get());
                Thread.sleep(10000);
              } catch (InterruptedException e) {
                //ignore
                LOGGER.error(e.getMessage(), e);
              }
            }
          }
        }.start();
      }
    }
  
    /**
     * Tranform the data as per the implementation.
     *
     * @return Array of Iterator with data. It can be processed parallel if implementation class wants
     * @throws CarbonDataLoadingException
     */
    public abstract Iterator<CarbonRowBatch>[] execute() throws CarbonDataLoadingException;
  
    /**
     * Process the batch of rows as per the step logic.
     *
     * @param rowBatch
     * @return processed row.
     */
    protected CarbonRowBatch processRowBatch(CarbonRowBatch rowBatch) {
      CarbonRowBatch newBatch = new CarbonRowBatch(rowBatch.getSize());
      while (rowBatch.hasNext()) {
        newBatch.addRow(null);
      }
      return newBatch;
    }
  
    /**
     * Get the step name for logging purpose.
     * @return Step name
     */
    protected abstract String getStepName();
  
    /**
     * This method registers all writer listeners and returns the listener
     * @param bucketId bucketId
     * @return
     */
    protected IndexWriterListener getIndexWriterListener(int bucketId) {
      // todo: this method is useless, will remove it later
      return null;
    }
  
    /**
     * Close all resources.This method is called after execute() is finished.
     * It will be called in both success and failure cases.
     */
    public void close() {
      if (!closed) {
        closed = true;
        LOGGER.info("Total rows processed in step " + this.getStepName() + ": " + rowCounter.get());
        if (child != null) {
          child.close();
        }
      }
    }
  
  }
  