net.sf.cglib.util

Class ParallelSorter

public abstract class ParallelSorter extends SorterTemplate

For the efficient sorting of multiple arrays in parallel.

Given two arrays of equal length and varying types, the standard technique for sorting them in parallel is to create a new temporary object for each row, store the objects in a temporary array, sort the array using a custom comparator, and the extract the original values back into their respective arrays. This is wasteful in both time and memory.

This class generates bytecode customized to the particular set of arrays you need to sort, in such a way that both arrays are sorted in-place, simultaneously.

Two sorting algorithms are provided. Quicksort is best when you only need to sort by a single column, as it requires very few comparisons and swaps. Mergesort is best used when sorting multiple columns, as it is a "stable" sort--that is, it does not affect the relative order of equal objects from previous sorts.

The mergesort algorithm here is an "in-place" variant, which while slower, does not require a temporary array.

Author: Chris Nokleberg

Nested Class Summary
static classParallelSorter.Generator
Method Summary
static ParallelSortercreate(Object[] arrays)
Create a new ParallelSorter object for a set of arrays.
voidmergeSort(int index)
voidmergeSort(int index, int lo, int hi)
Sort the arrays using an in-place merge sort.
voidmergeSort(int index, Comparator cmp)
Sort the arrays using an in-place merge sort.
voidmergeSort(int index, int lo, int hi, Comparator cmp)
Sort the arrays using an in-place merge sort.
abstract ParallelSorternewInstance(Object[] arrays)
voidquickSort(int index)
Sort the arrays using the quicksort algorithm.
voidquickSort(int index, int lo, int hi)
Sort the arrays using the quicksort algorithm.
voidquickSort(int index, Comparator cmp)
Sort the arrays using the quicksort algorithm.
voidquickSort(int index, int lo, int hi, Comparator cmp)
Sort the arrays using the quicksort algorithm.

Method Detail

create

public static ParallelSorter create(Object[] arrays)
Create a new ParallelSorter object for a set of arrays. You may sort the arrays multiple times via the same ParallelSorter object.

Parameters: arrays An array of arrays to sort. The arrays may be a mix of primitive and non-primitive types, but should all be the same length. loader ClassLoader for generated class, uses "current" if null

mergeSort

public void mergeSort(int index)

Parameters: index array (column) to sort by

mergeSort

public void mergeSort(int index, int lo, int hi)
Sort the arrays using an in-place merge sort.

Parameters: index array (column) to sort by lo starting array index (row), inclusive hi ending array index (row), exclusive

mergeSort

public void mergeSort(int index, Comparator cmp)
Sort the arrays using an in-place merge sort.

Parameters: index array (column) to sort by lo starting array index (row), inclusive hi ending array index (row), exclusive

mergeSort

public void mergeSort(int index, int lo, int hi, Comparator cmp)
Sort the arrays using an in-place merge sort.

Parameters: index array (column) to sort by lo starting array index (row), inclusive hi ending array index (row), exclusive cmp Comparator to use if the specified column is non-primitive

newInstance

public abstract ParallelSorter newInstance(Object[] arrays)

quickSort

public void quickSort(int index)
Sort the arrays using the quicksort algorithm.

Parameters: index array (column) to sort by

quickSort

public void quickSort(int index, int lo, int hi)
Sort the arrays using the quicksort algorithm.

Parameters: index array (column) to sort by lo starting array index (row), inclusive hi ending array index (row), exclusive

quickSort

public void quickSort(int index, Comparator cmp)
Sort the arrays using the quicksort algorithm.

Parameters: index array (column) to sort by cmp Comparator to use if the specified column is non-primitive

quickSort

public void quickSort(int index, int lo, int hi, Comparator cmp)
Sort the arrays using the quicksort algorithm.

Parameters: index array (column) to sort by lo starting array index (row), inclusive hi ending array index (row), exclusive cmp Comparator to use if the specified column is non-primitive

Copyright (c) 2001 - Apache Software Foundation