/*
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* Copyright 2011 gitblit.com.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.gitblit.utils;
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import java.io.Serializable;
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import java.util.Date;
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import java.util.Map;
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import java.util.concurrent.ConcurrentHashMap;
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/**
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* Reusable coarse date-based object cache. The date precision is in
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* milliseconds and in fast, concurrent systems this cache is too simplistic.
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* However, for the cases where its being used in Gitblit this cache technique
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* is just fine.
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*
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* @author James Moger
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*
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*/
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public class ObjectCache<X> implements Serializable {
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private static final long serialVersionUID = 1L;
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private final Map<String, CachedObject<X>> cache = new ConcurrentHashMap<String, CachedObject<X>>();
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private class CachedObject<Y> {
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public final String name;
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private volatile Date date;
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private volatile Y object;
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CachedObject(String name) {
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this.name = name;
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date = new Date(0);
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}
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@Override
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public String toString() {
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return getClass().getSimpleName() + ": " + name;
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}
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}
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public boolean hasCurrent(String name, Date date) {
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return cache.containsKey(name) && cache.get(name).date.compareTo(date) == 0;
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}
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public Date getDate(String name) {
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return cache.get(name).date;
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}
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public X getObject(String name) {
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if (cache.containsKey(name)) {
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return cache.get(name).object;
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}
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return null;
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}
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public void updateObject(String name, X object) {
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this.updateObject(name, new Date(), object);
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}
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public void updateObject(String name, Date date, X object) {
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CachedObject<X> obj;
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if (cache.containsKey(name)) {
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obj = cache.get(name);
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} else {
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obj = new CachedObject<X>(name);
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cache.put(name, obj);
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}
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obj.date = date;
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obj.object = object;
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}
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public Object remove(String name) {
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if (cache.containsKey(name)) {
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return cache.remove(name).object;
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}
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return null;
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}
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}
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