/**
* Copyright 2012 Akiban Technologies, Inc.
*
* Licensed 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 com.persistit;
import static org.junit.Assert.assertEquals;
import org.junit.Test;
import com.persistit.exception.PersistitException;
import com.persistit.policy.SplitPolicy;
public class ExchangeRebalanceTest extends PersistitUnitTestCase {
final StringBuilder sb = new StringBuilder();
@Override
public void setUp() throws Exception {
super.setUp();
while (sb.length() < Buffer.MAX_BUFFER_SIZE) {
sb.append(RED_FOX);
}
}
/**
* Construct a tree with two adjacent pages that are nearly full such that
* the second key B of the right page is long and has very small elided byte
* count relative to the first key A on that page. Removing key A requires
* the left sibling to have B as its max key. If B won't fit on the left
* page, then Persistit splits the left page to make room for it. Note that
* changes in key or page structure will likely break this test.
*
* @throws Exception
*/
@Test
public void testRebalanceException() throws Exception {
final Exchange exchange = _persistit.getExchange("persistit", "rebalance", true);
exchange.setSplitPolicy(SplitPolicy.LEFT_BIAS);
setUpPrettyFullBuffers(exchange, false, RED_FOX.length(), true);
System.out.printf("\ntestRebalanceException\n");
_persistit.checkAllVolumes();
final int beforeRemove = countSiblings(exchange, 0);
exchange.clear().append("b").previous(true);
exchange.remove();
_persistit.getCleanupManager().poll();
_persistit.checkAllVolumes();
final int afterRemove = countSiblings(exchange, 0);
assertEquals("Remove should have caused rebalance", beforeRemove + 1, afterRemove);
}
/**
* Similar logic to {@link #testRebalanceException()} except that the keys
* are carefully constructed on the index leaf level rather than the data
* level. To do this we use three long-ish records per major key in the data
* pages so that the key pattern in the index leaf table aligns as desired.
*
* @throws Exception
*/
@Test
public void testRebalanceIndexException() throws Exception {
final Exchange exchange = _persistit.getExchange("persistit", "rebalance", true);
exchange.setSplitPolicy(SplitPolicy.LEFT_BIAS);
setUpPrettyFullBuffers(exchange, true, 0, true);
System.out.printf("\ntestRebalanceIndexException\n");
_persistit.checkAllVolumes();
final int beforeRemove = countSiblings(exchange, 1);
exchange.clear().append("b").previous(true);
exchange.cut();
exchange.remove(Key.GT);
_persistit.getCleanupManager().poll();
_persistit.checkAllVolumes();
final int afterRemove = countSiblings(exchange, 1);
assertEquals("Remove should have caused rebalance", beforeRemove + 1, afterRemove);
}
private void setUpPrettyFullBuffers(final Exchange ex, final boolean asIndex, final int valueLength,
final boolean discontinuous) throws PersistitException {
final int depth = asIndex ? 1 : 0;
int a, b;
long leftPage = 0;
// load page A with keys of increasing length
for (a = 10;; a++) {
setUpDeepKey(ex, 'a', a);
storeValue(ex, valueLength, asIndex);
if (ex.getTree().getDepth() > depth) {
final Buffer b1 = ex.fetchBufferCopy(depth);
// Stop when nearly full
if (b1.getAvailableSize() < valueLength + 20) {
break;
}
leftPage = b1.getPageAddress();
}
}
// load additional keys into page B
for (b = a + 1;; b++) {
if (ex.getTree().getDepth() > depth) {
final Buffer b2 = ex.fetchBufferCopy(depth);
if (b2.getPageAddress() != leftPage && b2.getAvailableSize() < valueLength + 20) {
break;
}
}
setUpDeepKey(ex, discontinuous && b > a ? 'b' : 'a', b);
storeValue(ex, valueLength, asIndex);
}
}
private void setUpDeepKey(final Exchange ex, final char fill, final int n) {
ex.getKey().clear().append(keyString(fill, n, n - 34, 4, n)).append(1);
}
private void setupValue(final Exchange ex, final int valueLength) {
ex.getValue().put(sb.toString().substring(0, valueLength));
}
private void storeValue(final Exchange ex, final int valueLength, final boolean asIndex) throws PersistitException {
if (asIndex) {
// Fill up one data page so that the base key will be inserted into
// an index page
setupValue(ex, ex.getBufferPool().getBufferSize() / 4);
for (int i = 1; i < 4; i++) {
ex.cut().append(i).store();
}
} else {
setupValue(ex, valueLength);
ex.store();
}
}
String keyString(final char fill, final int length, final int prefix, final int width, final int k) {
final StringBuilder sb = new StringBuilder();
for (int i = 0; i < prefix && i < length; i++) {
sb.append(fill);
}
sb.append(String.format("%0" + width + "d", k));
for (int i = length - sb.length(); i < length; i++) {
sb.append(fill);
}
sb.setLength(length);
return sb.toString();
}
private int countSiblings(final Exchange exchange, final int level) throws PersistitException {
int count = 0;
exchange.clear().append(Key.BEFORE);
Buffer b = exchange.fetchBufferCopy(level);
while (true) {
count++;
final long rightSibling = b.getRightSibling();
if (rightSibling != 0) {
b = exchange.getBufferPool().getBufferCopy(exchange.getVolume(), rightSibling);
} else {
break;
}
}
return count;
}
}