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.core.datastore.page;
  
  import java.util.concurrent.Callable;
  
  import org.apache.carbondata.core.datastore.TableSpec;
  import org.apache.carbondata.core.datastore.page.encoding.EncodedColumnPage;
  import org.apache.carbondata.core.util.CarbonUtil;
  
  /**
   * Below class will be used to encode column pages for which local dictionary was generated
   * but all the pages in blocklet was not encoded with local dictionary.
   * This is required as all the pages of a column in blocklet either it will be local dictionary
   * encoded or without local dictionary encoded.
   */
  public class ActualDataBasedFallbackEncoder
      implements Callable<FallbackEncodedColumnPage> {
  
    /**
     * actual local dictionary generated column page
     */
    private EncodedColumnPage encodedColumnPage;
  
    /**
     * actual index in the page
     * this is required as in a blocklet few pages will be local dictionary
     * encoded and few pages will be plain text encoding
     * in this case local dictionary encoded page
     */
    private int pageIndex;
  
    public ActualDataBasedFallbackEncoder(EncodedColumnPage encodedColumnPage,
        int pageIndex) {
      this.encodedColumnPage = encodedColumnPage;
      this.pageIndex = pageIndex;
    }
  
    @Override
    public FallbackEncodedColumnPage call() throws Exception {
      // disable encoding using local dictionary
      encodedColumnPage.getActualPage().disableLocalDictEncoding();
  
      // get column spec for existing column page
      TableSpec.ColumnSpec columnSpec = encodedColumnPage.getActualPage().getColumnSpec();
      FallbackEncodedColumnPage fallbackEncodedColumnPage = CarbonUtil
          .getFallBackEncodedColumnPage(encodedColumnPage.getActualPage(), pageIndex, columnSpec);
      // here freeing the memory of raw column page as fallback is done and column page will not
      // be used.
      // This is required to free the memory once it is of no use
      encodedColumnPage.freeMemory();
      encodedColumnPage.cleanBuffer();
      return fallbackEncodedColumnPage;
    }
  }
  