package org.infinispan.distribution.ch.impl;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import net.jcip.annotations.Immutable;
import org.infinispan.commons.hash.Hash;
import org.infinispan.commons.marshall.AbstractExternalizer;
import org.infinispan.commons.util.Immutables;
import org.infinispan.commons.util.Util;
import org.infinispan.distribution.ch.ConsistentHash;
import org.infinispan.marshall.core.Ids;
import org.infinispan.remoting.transport.Address;
/**
* Default {@link ConsistentHash} implementation. This object is immutable.
*
* @author Dan Berindei
* @author anistor@redhat.com
* @since 5.2
*/
@Immutable
public class DefaultConsistentHash implements ConsistentHash {
private final Hash hashFunction;
private final int numOwners;
private final int numSegments;
/**
* The membership of the cache topology that uses this CH.
*/
private final List<Address> members;
private Map<Address, Float> capacityFactors;
/**
* The routing table.
*/
private final List<Address>[] segmentOwners;
private final int segmentSize;
public DefaultConsistentHash(Hash hashFunction, int numOwners, int numSegments, List<Address> members,
Map<Address, Float> capacityFactors, List<Address>[] segmentOwners) {
if (numSegments < 1)
throw new IllegalArgumentException("The number of segments must be strictly positive");
if (numOwners < 1)
throw new IllegalArgumentException("The number of owners must be strictly positive");
this.numOwners = numOwners;
this.numSegments = numSegments;
this.hashFunction = hashFunction;
this.members = new ArrayList<Address>(members);
this.capacityFactors = capacityFactors != null ? new HashMap<Address, Float>(capacityFactors) : null;
this.segmentOwners = new List[numSegments];
for (int i = 0; i < numSegments; i++) {
if (segmentOwners[i] == null || segmentOwners[i].isEmpty()) {
throw new IllegalArgumentException("Segment owner list cannot be null or empty");
}
this.segmentOwners[i] = Immutables.immutableListCopy(segmentOwners[i]);
}
this.segmentSize = Util.getSegmentSize(numSegments);
}
@Override
public Hash getHashFunction() {
return hashFunction;
}
@Override
public int getNumSegments() {
return numSegments;
}
@Override
public Set<Integer> getSegmentsForOwner(Address owner) {
if (owner == null) {
throw new IllegalArgumentException("owner cannot be null");
}
if (!members.contains(owner)) {
throw new IllegalArgumentException("Node " + owner + " is not a member");
}
Set<Integer> segments = new HashSet<Integer>();
for (int segment = 0; segment < segmentOwners.length; segment++) {
if (segmentOwners[segment].contains(owner)) {
segments.add(segment);
}
}
return segments;
}
@Override
public Set<Integer> getPrimarySegmentsForOwner(Address owner) {
if (owner == null) {
throw new IllegalArgumentException("owner cannot be null");
}
if (!members.contains(owner)) {
throw new IllegalArgumentException("Node " + owner + " is not a member");
}
Set<Integer> segments = new HashSet<Integer>();
for (int segment = 0; segment < segmentOwners.length; segment++) {
if (owner.equals(segmentOwners[segment].get(0))) {
segments.add(segment);
}
}
return segments;
}
@Override
public int getSegment(Object key) {
// The result must always be positive, so we make sure the dividend is positive first
return getNormalizedHash(key) / segmentSize;
}
public int getNormalizedHash(Object key) {
return hashFunction.hash(key) & Integer.MAX_VALUE;
}
public List<Integer> getSegmentEndHashes() {
List<Integer> hashes = new ArrayList<Integer>(numSegments);
for (int i = 0; i < numSegments; i++) {
hashes.add(((i + 1) % numSegments) * segmentSize);
}
return hashes;
}
@Override
public List<Address> locateOwnersForSegment(int segmentId) {
return segmentOwners[segmentId];
}
@Override
public Address locatePrimaryOwnerForSegment(int segmentId) {
return segmentOwners[segmentId].get(0);
}
@Override
public List<Address> getMembers() {
return members;
}
@Override
public int getNumOwners() {
return numOwners;
}
@Override
public Address locatePrimaryOwner(Object key) {
return locatePrimaryOwnerForSegment(getSegment(key));
}
@Override
public List<Address> locateOwners(Object key) {
return locateOwnersForSegment(getSegment(key));
}
@Override
public Set<Address> locateAllOwners(Collection<Object> keys) {
// Use a HashSet assuming most of the time the number of keys is small.
HashSet<Integer> segments = new HashSet<Integer>();
for (Object key : keys) {
segments.add(getSegment(key));
}
HashSet<Address> ownersUnion = new HashSet<Address>();
for (Integer segment : segments) {
ownersUnion.addAll(segmentOwners[segment]);
}
return ownersUnion;
}
@Override
public boolean isKeyLocalToNode(Address nodeAddress, Object key) {
int segment = getSegment(key);
for (Address a : segmentOwners[segment]) {
if (a.equals(nodeAddress))
return true;
}
return false;
}
@Override
public int hashCode() {
int result = numOwners;
result = 31 * result + numSegments;
result = 31 * result + members.hashCode();
return result;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
DefaultConsistentHash that = (DefaultConsistentHash) o;
if (numOwners != that.numOwners) return false;
if (numSegments != that.numSegments) return false;
if (!hashFunction.equals(that.hashFunction)) return false;
if (!members.equals(that.members)) return false;
for (int i = 0; i < numSegments; i++) {
if (!segmentOwners[i].equals(that.segmentOwners[i]))
return false;
}
return true;
}
@Override
public String toString() {
OwnershipStatistics stats = new OwnershipStatistics(this, members);
StringBuilder sb = new StringBuilder("DefaultConsistentHash{");
sb.append("ns = ").append(numSegments);
sb.append(", owners = (").append(members.size()).append(")[");
boolean first = true;
for (Address a : members) {
if (first) {
first = false;
} else {
sb.append(", ");
}
int primaryOwned = stats.getPrimaryOwned(a);
int owned = stats.getOwned(a);
sb.append(a).append(": ").append(primaryOwned).append('+').append(owned - primaryOwned);
}
sb.append("]}");
return sb.toString();
}
@Override
public String getRoutingTableAsString() {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < numSegments; i++) {
if (i > 0) {
sb.append(", ");
}
sb.append(i).append(":");
for (int j = 0; j < segmentOwners[i].size(); j++) {
sb.append(' ').append(members.indexOf(segmentOwners[i].get(j)));
}
}
return sb.toString();
}
/**
* Merges two consistent hash objects that have the same number of segments, numOwners and hash function.
* For each segment, the primary owner of the first CH has priority, the other primary owners become backups.
*/
public DefaultConsistentHash union(DefaultConsistentHash dch2) {
if (!hashFunction.equals(dch2.getHashFunction())) {
throw new IllegalArgumentException("The consistent hash objects must have the same hash function");
}
if (numSegments != dch2.getNumSegments()) {
throw new IllegalArgumentException("The consistent hash objects must have the same number of segments");
}
if (numOwners != dch2.getNumOwners()) {
throw new IllegalArgumentException("The consistent hash objects must have the same number of owners");
}
List<Address> unionMembers = new ArrayList<Address>(this.members);
mergeLists(unionMembers, dch2.getMembers());
List<Address>[] unionSegmentOwners = new List[numSegments];
for (int i = 0; i < numSegments; i++) {
unionSegmentOwners[i] = new ArrayList<Address>(locateOwnersForSegment(i));
mergeLists(unionSegmentOwners[i], dch2.locateOwnersForSegment(i));
}
Map<Address, Float> unionCapacityFactors = null;
if (this.capacityFactors != null || dch2.capacityFactors != null) {
unionCapacityFactors = new HashMap<Address, Float>();
if (this.capacityFactors != null) {
unionCapacityFactors.putAll(this.capacityFactors);
} else {
for (Address node : this.members) {
unionCapacityFactors.put(node, 1.0f);
}
}
if (dch2.capacityFactors != null) {
unionCapacityFactors.putAll(dch2.capacityFactors);
} else {
for (Address node : dch2.members) {
unionCapacityFactors.put(node, 1.0f);
}
}
}
return new DefaultConsistentHash(hashFunction, numOwners, numSegments, unionMembers, unionCapacityFactors, unionSegmentOwners);
}
/**
* Adds all elements from <code>src</code> list that do not already exist in <code>dest</code> list to the latter.
*
* @param dest List where elements are added
* @param src List of elements to add - this is never modified
*/
private void mergeLists(List<Address> dest, List<Address> src) {
for (Address node : src) {
if (!dest.contains(node)) {
dest.add(node);
}
}
}
public Map<Address, Float> getCapacityFactors() {
return capacityFactors;
}
public static class Externalizer extends AbstractExternalizer<DefaultConsistentHash> {
@Override
public void writeObject(ObjectOutput output, DefaultConsistentHash ch) throws IOException {
output.writeInt(ch.numSegments);
output.writeInt(ch.numOwners);
output.writeObject(ch.members);
output.writeObject(ch.capacityFactors);
output.writeObject(ch.hashFunction);
output.writeObject(ch.segmentOwners);
}
@Override
@SuppressWarnings("unchecked")
public DefaultConsistentHash readObject(ObjectInput unmarshaller) throws IOException, ClassNotFoundException {
int numSegments = unmarshaller.readInt();
int numOwners = unmarshaller.readInt();
List<Address> members = (List<Address>) unmarshaller.readObject();
Map<Address, Float> capacityFactors = (Map<Address, Float>)unmarshaller.readObject();
Hash hash = (Hash) unmarshaller.readObject();
List<Address>[] owners = (List<Address>[]) unmarshaller.readObject();
return new DefaultConsistentHash(hash, numOwners, numSegments, members, capacityFactors, owners);
}
@Override
public Integer getId() {
return Ids.DEFAULT_CONSISTENT_HASH;
}
@Override
public Set<Class<? extends DefaultConsistentHash>> getTypeClasses() {
return Collections.<Class<? extends DefaultConsistentHash>>singleton(DefaultConsistentHash.class);
}
}
}