/*
* 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.sling.discovery.impl.common;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import org.apache.sling.discovery.ClusterView;
import org.apache.sling.discovery.InstanceDescription;
/**
* Default implementation of the ClusterView interface.
* <p>
*/
public class DefaultClusterViewImpl implements ClusterView {
/** the id of this cluster view **/
private final String id;
/** the list of instances as part of this cluster **/
private final List<InstanceDescription> instances = new LinkedList<InstanceDescription>();
public DefaultClusterViewImpl(final String id) {
if (id == null || id.length() == 0) {
throw new IllegalArgumentException("id must not be null");
}
this.id = id;
}
@Override
public boolean equals(final Object obj) {
if (obj == null || !(obj instanceof DefaultClusterViewImpl)) {
return false;
}
final DefaultClusterViewImpl other = (DefaultClusterViewImpl) obj;
if (!this.id.equals(other.id)) {
return false;
}
if (!this.getLeader().equals(other.getLeader())) {
return false;
}
if (this.instances.size() != other.instances.size()) {
return false;
}
for (Iterator<InstanceDescription> it = instances.iterator(); it
.hasNext();) {
InstanceDescription instance = it.next();
if (!other.instances.contains(instance)) {
return false;
}
}
return true;
}
@Override
public int hashCode() {
return id.hashCode();
}
public String getId() {
return id;
}
/**
* Add the given instance to this cluster and set the cluster on the instance (back pointer)
* @param instance the instance to add to this cluster
*/
public void addInstanceDescription(final DefaultInstanceDescriptionImpl instance) {
if (instances.contains(instance)) {
throw new IllegalArgumentException("cannot add same instance twice");
}
if (instance.isLeader() && doGetLeader() != null) {
throw new IllegalArgumentException(
"cannot add another leader. there already is one");
}
instances.add(instance);
instance.setClusterView(this);
}
public List<InstanceDescription> getInstances() {
if (instances.size() == 0) {
throw new IllegalStateException("no instance was ever added");
}
return Collections.unmodifiableList(instances);
}
public InstanceDescription getLeader() {
final InstanceDescription result = doGetLeader();
if (result != null) {
return result;
}
throw new IllegalStateException("no leader was added");
}
/**
* Lookup the leader of this cluster
* @return the leader of this cluster - should never return null
*/
private InstanceDescription doGetLeader() {
for (Iterator<InstanceDescription> it = instances.iterator(); it
.hasNext();) {
InstanceDescription anInstance = it.next();
if (anInstance.isLeader()) {
return anInstance;
}
}
return null;
}
}