private void pushRun(int runBase, int runLen) {
            this.runBase[stackSize] = runBase;
            this.runLen[stackSize] = runLen;
            stackSize++;
        }
Pushes the specified run onto the pending-run stack.

@param runBase index of the first element in the run
@param runLen  the number of elements in the run
indexr-query-opt/src/main/java/org/apache/spark/util/collection/TimSort.java