org.apache.kafka.streams.processor.internals.QuickUnion Maven / Gradle / Ivy
/*
* 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.kafka.streams.processor.internals;
import java.util.HashMap;
import java.util.NoSuchElementException;
public class QuickUnion {
private final HashMap ids = new HashMap<>();
public void add(final T id) {
ids.put(id, id);
}
public boolean exists(final T id) {
return ids.containsKey(id);
}
/**
* @throws NoSuchElementException if the parent of this node is null
*/
public T root(final T id) {
T current = id;
T parent = ids.get(current);
if (parent == null) {
throw new NoSuchElementException("id: " + id.toString());
}
while (!parent.equals(current)) {
// do the path splitting
final T grandparent = ids.get(parent);
ids.put(current, grandparent);
current = parent;
parent = grandparent;
}
return current;
}
@SuppressWarnings("unchecked")
void unite(final T id1, final T... idList) {
for (final T id2 : idList) {
unitePair(id1, id2);
}
}
private void unitePair(final T id1, final T id2) {
final T root1 = root(id1);
final T root2 = root(id2);
if (!root1.equals(root2)) {
ids.put(root1, root2);
}
}
}