BigSegmentedArray.java

package com.browseengine.bobo.util;

import org.apache.lucene.util.OpenBitSet;

/**
 * Breaks up a regular java array by splitting it into a 2 dimensional array with
 * a predefined block size. Attempts to induce more efficient GC.
 */

public abstract class BigSegmentedArray {

  protected final int _size;
  protected final int _blockSize;
  protected final int _shiftSize;

  protected int _numrows;

  public BigSegmentedArray(int size) {
    _size = size;
    _blockSize = getBlockSize();
    _shiftSize = getShiftSize();
    _numrows = (size >> _shiftSize) + 1;
  }

  public int size() {
    return _size;
  }

  abstract int getBlockSize();

  // TODO: maybe this should be automatically calculated
  abstract int getShiftSize();

  abstract public int get(int id);

  public int capacity() {
    return _numrows * _blockSize;
  }

  abstract public void add(int id, int val);

  abstract public void fill(int val);

  abstract public void ensureCapacity(int size);

  abstract public int maxValue();

  abstract public int findValue(int val, int id, int maxId);

  abstract public int findValues(OpenBitSet bitset, int id, int maxId);

  abstract public int findValueRange(int minVal, int maxVal, int id, int maxId);

  abstract public int findBits(int bits, int id, int maxId);
}