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.

    • Constructor Detail

      • ParallelSorter

        protected ParallelSorter()
    • Method Detail

      • newInstance

        public abstract ParallelSorter newInstance​(java.lang.Object[] arrays)
      • create

        public static ParallelSorter create​(java.lang.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
      • len

        private int len()
      • 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,
                              java.util.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,
                              java.util.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
      • 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,
                              java.util.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,
                              java.util.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
      • chooseComparer

        private void chooseComparer​(int index,
                                    java.util.Comparator cmp)