package org.infinispan.distribution.ch;
import org.infinispan.commons.hash.Hash;
import org.infinispan.commons.hash.MurmurHash3;
import org.infinispan.distribution.TestAddress;
import org.infinispan.distribution.ch.impl.DefaultConsistentHash;
import org.infinispan.distribution.ch.impl.DefaultConsistentHashFactory;
import org.infinispan.distribution.ch.impl.OwnershipStatistics;
import org.infinispan.remoting.transport.Address;
import org.infinispan.test.AbstractInfinispanTest;
import org.testng.annotations.Test;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import static org.testng.Assert.assertEquals;
import static org.testng.Assert.assertSame;
import static org.testng.Assert.assertTrue;
/**
* Test the even distribution and number of moved segments after rebalance for {@link DefaultConsistentHashFactory}
*
* @author Dan Berindei
* @since 5.2
*/
@Test(groups = "unit", testName = "distribution.ch.DefaultConsistentHashFactoryTest")
public class DefaultConsistentHashFactoryTest extends AbstractInfinispanTest {
private int iterationCount = 0;
protected ConsistentHashFactory createConsistentHashFactory() {
return new DefaultConsistentHashFactory();
}
public void testConsistentHashDistribution() {
int[] numSegments = {1, 2, 4, 8, 16, 50, 100, 500};
int[] numNodes = {1, 2, 3, 4, 5, 7, 10, 100};
int[] numOwners = {1, 2, 3, 5};
// Since the number of nodes changes, the capacity factors are repeated
float[][] capacityFactors = {null, {1}, {2}, {1, 100}, {2, 0, 1}};
ConsistentHashFactory <DefaultConsistentHash> chf = createConsistentHashFactory();
Hash hashFunction = new MurmurHash3();
for (int nn : numNodes) {
List<Address> nodes = new ArrayList<Address>(nn);
for (int j = 0; j < nn; j++) {
nodes.add(new TestAddress(j, "TA"));
}
for (int ns : numSegments) {
if (nn < ns) {
for (int no : numOwners) {
for (float[] lf : capacityFactors) {
Map<Address, Float> lfMap = null;
if (lf != null) {
lfMap = new HashMap<Address, Float>();
for (int i = 0; i < nn; i++) {
lfMap.put(nodes.get(i), lf[i % lf.length]);
}
}
testConsistentHashModifications(chf, hashFunction, nodes, ns, no, lfMap);
}
}
}
}
}
}
private void testConsistentHashModifications(ConsistentHashFactory<DefaultConsistentHash> chf, Hash hashFunction, List<Address> nodes, int ns, int no, Map<Address, Float> lfMap) {
DefaultConsistentHash baseCH = chf.create(hashFunction, no, ns, nodes, lfMap);
assertEquals(lfMap, baseCH.getCapacityFactors());
checkDistribution(baseCH, lfMap, false);
// each element in the array is a pair of numbers: the first is the number of nodes to add
// the second is the number of nodes to remove (the index of the removed nodes are pseudo-random)
int[][] nodeChanges = {{1, 0}, {2, 0}, {0, 1}, {0, 2}, {1, 1}, {1, 2}, {2, 1}, {10, 0}, {0, 10}};
// check that the base CH is already balanced
List<Address> baseMembers = baseCH.getMembers();
assertSame(baseCH, chf.updateMembers(baseCH, baseMembers, lfMap));
assertSame(baseCH, chf.rebalance(baseCH));
// starting point, so that we don't confuse nodes
int nodeIndex = baseMembers.size();
for (int i = 0; i < nodeChanges.length; i++) {
int nodesToAdd = nodeChanges[i][0];
int nodesToRemove = nodeChanges[i][1];
if (nodesToRemove > baseMembers.size())
break;
if (nodesToRemove == baseMembers.size() && nodesToAdd == 0)
break;
List<Address> newMembers = new ArrayList<Address>(baseMembers);
HashMap<Address, Float> newCapacityFactors = lfMap != null ?
new HashMap<Address, Float>(lfMap) : null;
for (int k = 0; k < nodesToRemove; k++) {
int indexToRemove = Math.abs(baseCH.getHashFunction().hash(k) % newMembers.size());
if (newCapacityFactors != null) {
newCapacityFactors.remove(newMembers.get(indexToRemove));
}
newMembers.remove(indexToRemove);
}
for (int k = 0; k < nodesToAdd; k++) {
TestAddress address = new TestAddress(nodeIndex++, "TA");
newMembers.add(address);
if (newCapacityFactors != null) {
newCapacityFactors.put(address, lfMap.get(baseMembers.get(k % baseMembers.size())));
}
}
log.tracef("Testing consistent hash modifications iteration %d. Initial CH is %s. New members are %s",
iterationCount, baseCH, newMembers);
baseCH = checkModificationsIteration(chf, baseCH, nodesToAdd, nodesToRemove, newMembers, newCapacityFactors);
iterationCount++;
}
}
private DefaultConsistentHash checkModificationsIteration(ConsistentHashFactory<DefaultConsistentHash> chf,
DefaultConsistentHash baseCH, int nodesToAdd,
int nodesToRemove, List<Address> newMembers,
Map<Address, Float> lfMap) {
int actualNumOwners = computeActualNumOwners(baseCH.getNumOwners(), newMembers, lfMap);
// first phase: just update the members list, removing the leavers
// and adding new owners, but not necessarily assigning segments to them
DefaultConsistentHash updatedMembersCH = chf.updateMembers(baseCH, newMembers, lfMap);
assertEquals(lfMap, updatedMembersCH.getCapacityFactors());
if (nodesToRemove > 0) {
for (int l = 0; l < updatedMembersCH.getNumSegments(); l++) {
assertTrue(updatedMembersCH.locateOwnersForSegment(l).size() > 0);
assertTrue(updatedMembersCH.locateOwnersForSegment(l).size() <= actualNumOwners);
}
}
// second phase: rebalance with the new members list
DefaultConsistentHash rebalancedCH = chf.rebalance(updatedMembersCH);
checkDistribution(rebalancedCH, lfMap, false);
for (int l = 0; l < rebalancedCH.getNumSegments(); l++) {
assertTrue(rebalancedCH.locateOwnersForSegment(l).size() >= actualNumOwners);
}
checkMovedSegments(baseCH, rebalancedCH);
// union doesn't have to keep the CH balanced, but it does have to include owners from both CHs
DefaultConsistentHash unionCH = chf.union(updatedMembersCH, rebalancedCH);
for (int l = 0; l < updatedMembersCH.getNumSegments(); l++) {
assertTrue(unionCH.locateOwnersForSegment(l).containsAll(updatedMembersCH.locateOwnersForSegment(l)));
assertTrue(unionCH.locateOwnersForSegment(l).containsAll(rebalancedCH.locateOwnersForSegment(l)));
}
// switch to the new CH in the next iteration
assertEquals(rebalancedCH.getNumSegments(), baseCH.getNumSegments());
assertEquals(rebalancedCH.getNumOwners(), baseCH.getNumOwners());
assertEquals(rebalancedCH.getMembers(), newMembers);
baseCH = rebalancedCH;
return baseCH;
}
private void checkDistribution(ConsistentHash ch, Map<Address, Float> lfMap, boolean allowExtraOwners) {
int numSegments = ch.getNumSegments();
List<Address> nodes = ch.getMembers();
int numNodes = nodes.size();
int actualNumOwners = computeActualNumOwners(ch.getNumOwners(), nodes, lfMap);
OwnershipStatistics stats = new OwnershipStatistics(nodes);
for (int i = 0; i < numSegments; i++) {
List<Address> owners = ch.locateOwnersForSegment(i);
if (!allowExtraOwners) {
assertEquals(owners.size(), actualNumOwners);
} else {
assertTrue(owners.size() >= actualNumOwners);
}
stats.incPrimaryOwned(owners.get(0));
for (int j = 0; j < owners.size(); j++) {
Address owner = owners.get(j);
stats.incOwned(owner);
assertEquals(owners.indexOf(owner), j, "Found the same owner twice in the owners list");
}
}
float totalCapacity = computeTotalCapacity(nodes, lfMap);
float maxCapacityFactor = computeMaxCapacityFactor(nodes, lfMap);
Map<Address, Float> expectedOwnedMap = computeExpectedOwned(numSegments, numNodes, actualNumOwners, nodes, lfMap);
for (Address node : nodes) {
float capacityFactor = lfMap != null ? lfMap.get(node) : 1;
float expectedPrimaryOwned = expectedPrimaryOwned(numSegments, numNodes, totalCapacity, capacityFactor);
float deviationPrimaryOwned = allowedDeviationPrimaryOwned(numSegments, numNodes, totalCapacity, maxCapacityFactor);
int minPrimaryOwned = (int) Math.floor(expectedPrimaryOwned - deviationPrimaryOwned);
int maxPrimaryOwned = (int) Math.ceil(expectedPrimaryOwned + deviationPrimaryOwned);
if (!allowExtraOwners) {
int primaryOwned = stats.getPrimaryOwned(node);
assertTrue(minPrimaryOwned <= primaryOwned);
assertTrue(primaryOwned <= maxPrimaryOwned);
}
float expectedOwned = expectedOwnedMap.get(node);
float deviationOwned = allowedDeviationOwned(numSegments, actualNumOwners, numNodes, totalCapacity, maxCapacityFactor);
int minOwned = (int) Math.floor(expectedOwned - deviationOwned);
int maxOwned = (int) Math.ceil(expectedOwned + deviationOwned);
int owned = stats.getOwned(node);
assertTrue(Math.floor(minOwned) <= owned);
if (!allowExtraOwners) {
assertTrue(owned <= Math.ceil(maxOwned));
}
}
}
public int computeActualNumOwners(int numOwners, List<Address> members, Map<Address, Float> capacityFactors) {
if (capacityFactors == null)
return Math.min(numOwners, members.size());
int nodesWithLoad = 0;
for (Address node : members) {
if (capacityFactors.get(node) != 0) {
nodesWithLoad++;
}
}
return Math.min(numOwners, nodesWithLoad);
}
protected float expectedPrimaryOwned(int numSegments, int numNodes, float totalCapacity, float nodeLoad) {
return Math.min(numSegments * nodeLoad / totalCapacity, numSegments);
}
protected float allowedDeviationPrimaryOwned(int numSegments, int numNodes, float totalCapacity, float maxCapacityFactor) {
return numNodes * maxCapacityFactor / totalCapacity;
}
protected Map<Address, Float> computeExpectedOwned(int numSegments, int numNodes, int actualNumOwners,
Collection<Address> nodes,
final Map<Address, Float> capacityFactors) {
Map<Address, Float> expectedOwned = new HashMap<Address, Float>();
if (capacityFactors == null) {
float expected = Math.min(numSegments, (float) numSegments * actualNumOwners / numNodes);
for (Address node : nodes) {
expectedOwned.put(node, expected);
}
return expectedOwned;
}
List<Address> sortedNodes = new ArrayList<Address>(nodes);
Collections.sort(sortedNodes, new Comparator<Address>() {
@Override
public int compare(Address o1, Address o2) {
// Reverse order
return (int) Math.signum(capacityFactors.get(o2) - capacityFactors.get(o1));
}
});
float totalCapacity = computeTotalCapacity(nodes, capacityFactors);
int remainingCopies = actualNumOwners * numSegments;
for (Address node : sortedNodes) {
float nodeLoad = capacityFactors.get(node);
float nodeSegments;
if (remainingCopies * nodeLoad / totalCapacity > numSegments) {
nodeSegments = numSegments;
totalCapacity -= nodeLoad;
remainingCopies -= nodeSegments;
} else {
nodeSegments = nodeLoad != 0 ? remainingCopies * nodeLoad / totalCapacity : 0;
}
expectedOwned.put(node, nodeSegments);
}
return expectedOwned;
}
protected float allowedDeviationOwned(int numSegments, int actualNumOwners, int numNodes, float totalCapacity,
float maxCapacityFactor) {
return numNodes * maxCapacityFactor / totalCapacity;
}
private float computeTotalCapacity(Collection<Address> nodes, Map<Address, Float> capacityFactors) {
if (capacityFactors == null)
return nodes.size();
float totalCapacity = 0;
for (Address node : nodes) {
totalCapacity += capacityFactors.get(node);
}
return totalCapacity;
}
private float computeMaxCapacityFactor(Collection<Address> nodes, Map<Address, Float> capacityFactors) {
if (capacityFactors == null)
return 1;
float maxCapacityFactor = 0;
for (Address node : nodes) {
Float capacityFactor = capacityFactors.get(node);
if (capacityFactor > maxCapacityFactor) {
maxCapacityFactor = capacityFactor;
}
}
return maxCapacityFactor;
}
protected int allowedExtraMoves(DefaultConsistentHash oldCH, DefaultConsistentHash newCH,
int leaverSegments) {
return (int) Math.ceil(0.25 * oldCH.getNumSegments());
}
private void checkMovedSegments(DefaultConsistentHash oldCH, DefaultConsistentHash newCH) {
int numSegments = oldCH.getNumSegments();
int numOwners = oldCH.getNumOwners();
Set<Address> oldMembers = new HashSet<Address>(oldCH.getMembers());
Set<Address> newMembers = new HashSet<Address>(newCH.getMembers());
// Compute the number of segments owned by members that left
int leaverSegments = 0;
for (Address node : oldMembers) {
if (!newMembers.contains(node)) {
leaverSegments += oldCH.getSegmentsForOwner(node).size();
}
}
// Compute the number of segments where an old node became an owner
int oldMembersAddedSegments = 0;
for (int segment = 0; segment < numSegments; segment++) {
ArrayList<Address> oldMembersAdded = new ArrayList<Address>(newCH.locateOwnersForSegment(segment));
oldMembersAdded.removeAll(oldCH.locateOwnersForSegment(segment));
oldMembersAdded.retainAll(oldMembers);
oldMembersAddedSegments += oldMembersAdded.size();
}
int movedSegments = oldMembersAddedSegments - leaverSegments;
int expectedExtraMoves = allowedExtraMoves(oldCH, newCH, leaverSegments);
if (movedSegments > expectedExtraMoves) {
log.debugf("%d of %d segments moved, %d (%fx) more than expected (%d)", movedSegments, numSegments,
movedSegments - expectedExtraMoves, (float) movedSegments / expectedExtraMoves, expectedExtraMoves);
}
assert movedSegments <= expectedExtraMoves
: String.format("Two many moved segments between %s and %s: expected %d, got %d",
oldCH, newCH, expectedExtraMoves, oldMembersAddedSegments);
}
protected <T> Set<T> symmetricalDiff(Collection <T> set1, Collection<T> set2) {
HashSet<T> commonMembers = new HashSet<T>(set1);
commonMembers.retainAll(set2);
HashSet<T> symDiffMembers = new HashSet<T>(set1);
symDiffMembers.addAll(set2);
symDiffMembers.removeAll(commonMembers);
return symDiffMembers;
}
public void test1() {
DefaultConsistentHashFactory chf = new DefaultConsistentHashFactory();
TestAddress A = new TestAddress(0, "A");
TestAddress B = new TestAddress(1, "B");
TestAddress C = new TestAddress(2, "C");
TestAddress D = new TestAddress(3, "D");
DefaultConsistentHash ch1 = chf.create(new MurmurHash3(), 2, 60, Arrays.<Address>asList(A), null);
//System.out.println(ch1);
DefaultConsistentHash ch2 = chf.updateMembers(ch1, Arrays.<Address>asList(A, B), null);
ch2 = chf.rebalance(ch2);
//System.out.println(ch2);
DefaultConsistentHash ch3 = chf.updateMembers(ch2, Arrays.<Address>asList(A, B, C), null);
ch3 = chf.rebalance(ch3);
//System.out.println(ch3);
DefaultConsistentHash ch4 = chf.updateMembers(ch3, Arrays.<Address>asList(A, B, C, D), null);
ch4 = chf.rebalance(ch4);
//System.out.println(ch4);
}
}