package org.infinispan.distribution.ch.impl;
import org.infinispan.commons.hash.Hash;
import org.infinispan.commons.marshall.AbstractExternalizer;
import org.infinispan.distribution.ch.ConsistentHash;
import org.infinispan.marshall.core.Ids;
import org.infinispan.remoting.transport.Address;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.*;
/**
* Special implementation of {@link org.infinispan.distribution.ch.ConsistentHash} for replicated caches.
* The hash-space has several segments owned by all members and the primary ownership of each segment is evenly
* spread between members.
*
* @author Dan Berindei
* @author anistor@redhat.com
* @since 5.2
*/
public class ReplicatedConsistentHash implements ConsistentHash {
private final Hash hashFunction;
private final int[] primaryOwners;
private final List<Address> members;
private final Set<Address> membersSet;
private final Set<Integer> segments;
public ReplicatedConsistentHash(Hash hashFunction, List<Address> members, int[] primaryOwners) {
this.hashFunction = hashFunction;
this.members = Collections.unmodifiableList(new ArrayList<Address>(members));
this.membersSet = Collections.unmodifiableSet(new HashSet<Address>(members));
this.primaryOwners = primaryOwners;
Set<Integer> segmentIds = new HashSet<Integer>(primaryOwners.length);
for (int i = 0; i < primaryOwners.length; i++) {
segmentIds.add(i);
}
segments = Collections.unmodifiableSet(segmentIds);
}
@Override
public int getNumSegments() {
return primaryOwners.length;
}
@Override
public int getNumOwners() {
return members.size();
}
@Override
public List<Address> getMembers() {
return members;
}
@Override
public Hash getHashFunction() {
return hashFunction;
}
@Override
public int getSegment(Object key) {
// The result must always be positive, so we make sure the dividend is positive first
return (hashFunction.hash(key) & Integer.MAX_VALUE) % primaryOwners.length;
}
@Override
public List<Address> locateOwnersForSegment(int segmentId) {
Address primaryOwner = locatePrimaryOwnerForSegment(segmentId);
List<Address> owners = new ArrayList<Address>(members.size());
owners.add(primaryOwner);
for (Address member : members) {
if (!member.equals(primaryOwner)) {
owners.add(member);
}
}
return owners;
}
@Override
public Address locatePrimaryOwnerForSegment(int segmentId) {
return members.get(primaryOwners[segmentId]);
}
@Override
public Set<Integer> getSegmentsForOwner(Address owner) {
if (owner == null) {
throw new IllegalArgumentException("owner cannot be null");
}
if (!membersSet.contains(owner)) {
throw new IllegalArgumentException("The node is not a member : " + owner);
}
return segments;
}
@Override
public Set<Integer> getPrimarySegmentsForOwner(Address owner) {
int index = members.indexOf(owner);
if (index == -1) {
throw new IllegalArgumentException("The node is not a member : " + owner);
}
Set<Integer> primarySegments = new HashSet<Integer>();
for (int i = 0; i < primaryOwners.length; ++i) {
if (primaryOwners[i] == index) {
primarySegments.add(i);
}
}
return primarySegments;
}
@Override
public String getRoutingTableAsString() {
return Arrays.toString(primaryOwners);
}
@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) {
return membersSet;
}
@Override
public boolean isKeyLocalToNode(Address nodeAddress, Object key) {
return membersSet.contains(nodeAddress);
}
@Override
public String toString() {
OwnershipStatistics stats = new OwnershipStatistics(this, members);
StringBuilder sb = new StringBuilder("ReplicatedConsistentHash{");
sb.append("ns = ").append(segments.size());
for (Address a : members) {
sb.append(", ").append(a).append(": ").append(stats.getPrimaryOwned(a));
}
sb.append('}');
return sb.toString();
}
public static class Externalizer extends AbstractExternalizer<ReplicatedConsistentHash> {
@Override
public void writeObject(ObjectOutput output, ReplicatedConsistentHash ch) throws IOException {
output.writeObject(ch.hashFunction);
output.writeObject(ch.members);
output.writeObject(ch.primaryOwners);
}
@Override
@SuppressWarnings("unchecked")
public ReplicatedConsistentHash readObject(ObjectInput unmarshaller) throws IOException, ClassNotFoundException {
Hash hashFunction = (Hash) unmarshaller.readObject();
List<Address> members = (List<Address>) unmarshaller.readObject();
int[] primaryOwners = (int[]) unmarshaller.readObject();
return new ReplicatedConsistentHash(hashFunction, members, primaryOwners);
}
@Override
public Integer getId() {
return Ids.REPLICATED_CONSISTENT_HASH;
}
@Override
public Set<Class<? extends ReplicatedConsistentHash>> getTypeClasses() {
return Collections.<Class<? extends ReplicatedConsistentHash>>singleton(ReplicatedConsistentHash.class);
}
}
}