/* | |
* 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(); | |
} | |
} |