Example usage for org.apache.hadoop.util IndexedSortable compare

Introduction

In this page you can find the example usage for org.apache.hadoop.util IndexedSortable compare.

Prototype

int compare(int i, int j);

Source Link

Document

Compare items at the given addresses consistent with the semantics of java.util.Comparator#compare(Object,Object) .

Usage

From source file:com.ricemap.spateDB.util.MergeSorter.java

License:Apache License

@Override
public void sort(IndexedSortable s, final int l, final int r, Progressable rep) {
    for (int step = 2; step < (r - l) * 2; step *= 2) {
        for (int i = l; i < r; i += step) {
            // In this iteration, we need to merge the two sublists
            // [i, i + step / 2), [i + step / 2, i + step)

            int i1 = i;
            int j1 = i + step / 2;
            int j2 = Math.min(i + step, r);
            // In each iteration: Elements in the sublist [i, i1) are in their
            // correct position. i.e. each element in this sublist is less than
            // every element on the sublist [i1, j2)
            // The loop needs to merge the sublists [i1, j1), [j1, j2)

            while (j1 < j2) {
                // Step 1: Skip elements in the left list < minimum of right list
                while (i1 < j1 && s.compare(i1, j1) <= 0) {
                    i1++;/*from w  w w  .jav a  2  s.c o m*/
                }

                if (i1 == j1) {
                    // Range is already merged. Terminate the loop
                    break;
                }

                // Step 2: Find all elements starting from j1 that needs to be moved
                // to i1
                // Note: We don't need to compare [j1] as we know it's less than [i1]
                int old_j1 = j1++;
                while (j1 < j2 && s.compare(i1, j1) > 0) {
                    j1++;
                }

                // Step 3: Move the elements [old_j1, j1) to the position i1
                shift(s, old_j1, j1, i1);

                // Step 4: Update the indices.
                i1 += (j1 - old_j1);
                // I already compared [i1] and I know it's less than or equal to [j1]
                i1++;
                // Now the sublist [i, i1) is merged
            }
        }
    }
}

---