AbstractConstantColumnShard.java

/**
 * diqube: Distributed Query Base.
 *
 * Copyright (C) 2015 Bastian Gloeckle
 *
 * This file is part of diqube.
 *
 * diqube is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.diqube.data.column;

import org.diqube.data.dictionary.Dictionary;

/**
 * Abstract base implementation of a {@link ConstantColumnShard}.
 * 
 * @author Bastian Gloeckle
 */
public abstract class AbstractConstantColumnShard implements ConstantColumnShard {
  protected Dictionary<?> columnShardDictionary;

  protected String name;

  protected ColumnType columnType;

  private long firstRowId;

  private Object value;

  /**
   * @param columnType
   *          Data type of the column
   * @param name
   *          Name of the column
   * @param value
   *          The constant value that should be used for all rows.
   * @param firstRowId
   *          The first row ID of this {@link ColumnShard}.
   */
  protected AbstractConstantColumnShard(ColumnType columnType, String name, Object value, long firstRowId) {
    this.columnType = columnType;
    this.name = name;
    this.value = value;
    this.firstRowId = firstRowId;
    this.columnShardDictionary = createColumnShardDictionary(value);
  }

  /**
   * Create a Dictionary which will be the column shard dictionary. This needs to map the given value to ColumnValue ID
   * 0L.
   */
  abstract protected Dictionary<?> createColumnShardDictionary(Object value);

  @Override
  public String getName() {
    return name;
  }

  @Override
  public Dictionary<?> getColumnShardDictionary() {
    return columnShardDictionary;
  }

  @Override
  public ColumnType getColumnType() {
    return columnType;
  }

  @Override
  public long getFirstRowId() {
    return firstRowId;
  }

  @Override
  public Object getValue() {
    return value;
  }

  @Override
  public long getSingleColumnDictId() {
    return 0L; // constant, as created by #createColumnShardDictionary
  }

  @Override
  public long calculateApproximateSizeInBytes() {
    return 16 + // object header of this.
        24 + // small fields
        name.getBytes().length + //
        columnShardDictionary.calculateApproximateSizeInBytes(); // ignore other minor data.
  }
}