/*
* Copyright 2008-2009 LinkedIn, 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 org.sdnplatform.sync.internal.version;
import java.util.List;
import java.util.ListIterator;
import org.sdnplatform.sync.IInconsistencyResolver;
import org.sdnplatform.sync.Versioned;
import org.sdnplatform.sync.IVersion.Occurred;
import com.google.common.collect.Lists;
/**
* An inconsistency resolver that uses the object VectorClocks leaving only a
* set of concurrent versions remaining.
*
*
*/
public class VectorClockInconsistencyResolver<T>
implements IInconsistencyResolver<Versioned<T>> {
public List<Versioned<T>> resolveConflicts(List<Versioned<T>> items) {
int size = items.size();
if(size <= 1)
return items;
List<Versioned<T>> newItems = Lists.newArrayList();
for(Versioned<T> v1: items) {
boolean found = false;
for(ListIterator<Versioned<T>> it2 =
newItems.listIterator(); it2.hasNext();) {
Versioned<T> v2 = it2.next();
Occurred compare = v1.getVersion().compare(v2.getVersion());
if(compare == Occurred.AFTER) {
if(found)
it2.remove();
else
it2.set(v1);
}
if(compare != Occurred.CONCURRENTLY)
found = true;
}
if(!found)
newItems.add(v1);
}
return newItems;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
return (o != null && getClass() == o.getClass());
}
@Override
public int hashCode() {
return getClass().hashCode();
}
}