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/*
* 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.zkoss.zel.impl.util;
import java.util.Map;
import java.util.Objects;
import java.util.WeakHashMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;
public final class ConcurrentCache {
private final int size;
private final Map eden;
private final Map longterm;
public ConcurrentCache(int size) {
this.size = size;
this.eden = new ConcurrentHashMap(size);
this.longterm = new WeakHashMap(size);
}
public V get(K k) {
V v = this.eden.get(k);
if (v == null) {
synchronized (longterm) {
v = this.longterm.get(k);
}
if (v != null) {
this.eden.put(k, v);
}
}
return v;
}
public void put(K k, V v) {
if (this.eden.size() >= size) {
synchronized (longterm) {
this.longterm.putAll(this.eden);
}
this.eden.clear();
}
this.eden.put(k, v);
}
// copied from ConcurrentMap
public V computeIfAbsent(K key, Function mappingFunction) {
Objects.requireNonNull(mappingFunction);
V oldValue, newValue;
return ((oldValue = get(key)) == null && (newValue = mappingFunction.apply(key)) != null
&& (oldValue = putIfAbsent(key, newValue)) == null) ? newValue : oldValue;
}
public V putIfAbsent(K key, V value) {
if (this.eden.size() >= size) {
synchronized (longterm) {
this.longterm.putAll(this.eden);
}
this.eden.clear();
}
return this.eden.putIfAbsent(key, value);
}
}