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/*
* Copyright 2011 gitblit.com.
*
* 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 com.gitblit.utils;
import java.io.Serializable;
import java.util.Date;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
* Reusable coarse date-based object cache. The date precision is in
* milliseconds and in fast, concurrent systems this cache is too simplistic.
* However, for the cases where its being used in Gitblit this cache technique
* is just fine.
*
* @author James Moger
*
*/
public class ObjectCache<X> implements Serializable {
private static final long serialVersionUID = 1L;
private final Map<String, CachedObject<X>> cache = new ConcurrentHashMap<String, CachedObject<X>>();
private class CachedObject<Y> {
public final String name;
private volatile Date date;
private volatile Y object;
CachedObject(String name) {
this.name = name;
date = new Date(0);
}
@Override
public String toString() {
return getClass().getSimpleName() + ": " + name;
}
}
public void clear() {
cache.clear();
}
public boolean hasCurrent(String name, Date date) {
return cache.containsKey(name) && cache.get(name).date.compareTo(date) == 0;
}
public Date getDate(String name) {
return cache.get(name).date;
}
public X getObject(String name) {
if (cache.containsKey(name)) {
return cache.get(name).object;
}
return null;
}
public void updateObject(String name, X object) {
this.updateObject(name, new Date(), object);
}
public void updateObject(String name, Date date, X object) {
CachedObject<X> obj;
if (cache.containsKey(name)) {
obj = cache.get(name);
} else {
obj = new CachedObject<X>(name);
cache.put(name, obj);
}
obj.date = date;
obj.object = object;
}
public X remove(String name) {
if (cache.containsKey(name)) {
return cache.remove(name).object;
}
return null;
}
public int size() {
return cache.size();
}
}
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