/**
* 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.mahout.fpm.pfpgrowth.fpgrowth;
import com.google.common.collect.Maps;
import java.util.Collections;
import java.util.Map;
import java.util.PriorityQueue;
public class LeastKCache<K extends Comparable<? super K>,V> {
private final int capacity;
private final Map<K,V> cache;
private final PriorityQueue<K> queue;
public LeastKCache(int capacity) {
this.capacity = capacity;
cache = Maps.newHashMapWithExpectedSize(capacity);
queue = new PriorityQueue<K>(capacity + 1, Collections.reverseOrder());
}
public final V get(K key) {
return cache.get(key);
}
public final void set(K key, V value) {
if (!contains(key)) {
queue.add(key);
}
cache.put(key, value);
while (queue.size() > capacity) {
K k = queue.poll();
cache.remove(k);
}
}
public final long size() {
return cache.size();
}
public final boolean contains(K key) {
return cache.containsKey(key);
}
}