/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.flink.runtime.operators.sort;
public final class QuickSort implements IndexedSorter {
private static final IndexedSorter alt = new HeapSort();
public QuickSort() {
}
/**
* Fix the records into sorted order, swapping when the first record is
* greater than the second record.
*
* @param s paged sortable
* @param pN page number of first record
* @param pO page offset of first record
* @param rN page number of second record
* @param rO page offset of second record
*/
private static void fix(IndexedSortable s, int pN, int pO, int rN, int rO) {
if (s.compare(pN, pO, rN, rO) > 0) {
s.swap(pN, pO, rN, rO);
}
}
/**
* Deepest recursion before giving up and doing a heapsort.
* Returns 2 * ceil(log(n)).
*/
protected static int getMaxDepth(int x) {
if (x <= 0) {
throw new IllegalArgumentException("Undefined for " + x);
}
return (32 - Integer.numberOfLeadingZeros(x - 1)) << 2;
}
/**
* Sort the given range of items using quick sort. {@inheritDoc} If the recursion depth falls below
* {@link #getMaxDepth}, then switch to {@link HeapSort}.
*/
public void sort(final IndexedSortable s, int p, int r) {
int recordsPerSegment = s.recordsPerSegment();
int recordSize = s.recordSize();
int maxOffset = recordSize * (recordsPerSegment - 1);
int pN = p / recordsPerSegment;
int pO = (p % recordsPerSegment) * recordSize;
int rN = r / recordsPerSegment;
int rO = (r % recordsPerSegment) * recordSize;
sortInternal(s, recordsPerSegment, recordSize, maxOffset, p, pN, pO, r, rN, rO, getMaxDepth(r - p));
}
public void sort(IndexedSortable s) {
sort(s, 0, s.size());
}
/**
* Sort the given range of items using quick sort. If the recursion depth falls below
* {@link #getMaxDepth}, then switch to {@link HeapSort}.
*
* @param s paged sortable
* @param recordsPerSegment number of records per memory segment
* @param recordSize number of bytes per record
* @param maxOffset offset of a last record in a memory segment
* @param p index of first record in range
* @param pN page number of first record in range
* @param pO page offset of first record in range
* @param r index of last-plus-one'th record in range
* @param rN page number of last-plus-one'th record in range
* @param rO page offset of last-plus-one'th record in range
* @param depth recursion depth
*
* @see #sort(IndexedSortable, int, int)
*/
private static void sortInternal(final IndexedSortable s, int recordsPerSegment, int recordSize, int maxOffset,
int p, int pN, int pO, int r, int rN, int rO, int depth) {
while (true) {
if (r - p < 13) {
// switch to insertion sort
int i = p+1, iN, iO; if (pO == maxOffset) { iN = pN+1; iO = 0; } else { iN = pN; iO = pO+recordSize; }
while (i < r) {
int j = i, jN = iN, jO = iO;
int jd = j-1, jdN, jdO; if (jO == 0) { jdN = jN-1; jdO = maxOffset; } else { jdN = jN; jdO = jO-recordSize; }
while (j > p && s.compare(jdN, jdO, jN, jO) > 0) {
s.swap(jN, jO, jdN, jdO);
j = jd; jN = jdN; jO = jdO;
jd--; if (jdO == 0) { jdN--; jdO = maxOffset; } else { jdO -= recordSize; }
}
i++; if (iO == maxOffset) { iN++; iO = 0; } else { iO += recordSize; }
}
return;
}
if (--depth < 0) {
// switch to heap sort
alt.sort(s, p, r);
return;
}
int rdN, rdO; if (rO == 0) { rdN = rN-1; rdO = maxOffset; } else { rdN = rN; rdO = rO-recordSize; }
int m = (p+r)>>>1, mN = m / recordsPerSegment, mO = (m % recordsPerSegment) * recordSize;
// select, move pivot into first position
fix(s, mN, mO, pN, pO);
fix(s, mN, mO, rdN, rdO);
fix(s, pN, pO, rdN, rdO);
// Divide
int i = p, iN = pN, iO = pO;
int j = r, jN = rN, jO = rO;
int ll = p, llN = pN, llO = pO;
int rr = r, rrN = rN, rrO = rO;
int cr;
while (true) {
i++; if (iO == maxOffset) { iN++; iO = 0; } else { iO += recordSize; }
while (i < j) {
if ((cr = s.compare(iN, iO, pN, pO)) > 0) {
break;
}
if (0 == cr) {
ll++; if (llO == maxOffset) { llN++; llO = 0; } else { llO += recordSize; }
if (ll != i) {
s.swap(llN, llO, iN, iO);
}
}
i++; if (iO == maxOffset) { iN++; iO = 0; } else { iO += recordSize; }
}
j--; if (jO == 0) { jN--; jO = maxOffset; } else { jO -= recordSize; }
while (j > i) {
if ((cr = s.compare(pN, pO, jN, jO)) > 0) {
break;
}
if (0 == cr) {
rr--; if (rrO == 0) { rrN--; rrO = maxOffset; } else { rrO -= recordSize; }
if (rr != j) {
s.swap(rrN, rrO, jN, jO);
}
}
j--; if (jO == 0) { jN--; jO = maxOffset; } else { jO -= recordSize; }
}
if (i < j) {
s.swap(iN, iO, jN, jO);
} else {
break;
}
}
j = i; jN = iN; jO = iO;
// swap pivot- and all eq values- into position
while (ll >= p) {
i--; if (iO == 0) { iN--; iO = maxOffset; } else { iO -= recordSize; }
s.swap(llN, llO, iN, iO);
ll--; if (llO == 0) { llN--; llO = maxOffset; } else { llO -= recordSize; }
}
while (rr < r) {
s.swap(rrN, rrO, jN, jO);
rr++; if (rrO == maxOffset) { rrN++; rrO = 0; } else { rrO += recordSize; }
j++; if (jO == maxOffset) { jN++; jO = 0; } else { jO += recordSize; }
}
// Conquer
// Recurse on smaller interval first to keep stack shallow
assert i != j;
if (i - p < r - j) {
sortInternal(s, recordsPerSegment, recordSize, maxOffset, p, pN, pO, i, iN, iO, depth);
p = j; pN = jN; pO = jO;
} else {
sortInternal(s, recordsPerSegment, recordSize, maxOffset, j, jN, jO, r, rN, rO, depth);
r = i; rN = iN; rO = iO;
}
}
}
}