/*
* Copyright (c) 1998-2011 Caucho Technology -- all rights reserved
*
* This file is part of Resin(R) Open Source
*
* Each copy or derived work must preserve the copyright notice and this
* notice unmodified.
*
* Resin Open Source is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Resin Open Source is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
* of NON-INFRINGEMENT. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with Resin Open Source; if not, write to the
* Free SoftwareFoundation, Inc.
* 59 Temple Place, Suite 330
* Boston, MA 02111-1307 USA
*
* @author Scott Ferguson
*/
package com.caucho.util;
/**
* A single item timed cache. The item will remain valid until it expires.
* TimedItem can simplify database caching.
*
* <pre><code>
* TimedItem currentStories = new TimedItem(60000);
*
* public ArrayList getCurrentStories()
* {
* ArrayList storyList = (ArrayList) currentStories.get();
*
* if (storyList == null) {
* storyList = DB.queryStoryDatabase();
* currentStories.put(storyList);
* }
*
* return storyList;
* }
* </code></pre>
*/
public class TimedItem {
private long expireInterval;
private long createTime;
private Object value;
/**
* Create a new timed item with a specified update time
*
* @param expireInterval the time in milliseconds the item remains valid.
*/
public TimedItem(long expireInterval)
{
this.expireInterval = expireInterval;
}
/**
* Returns the expire time for this TimedItem.
*/
public long getExpireInterval()
{
return expireInterval;
}
/**
* Sets the expire time for this timedItem.
*/
public void setExpireInterval(long expireInterval)
{
this.expireInterval = expireInterval;
}
/**
* Sets the value.
*/
public void put(Object value)
{
createTime = Alarm.getCurrentTime();
this.value = value;
}
/**
* Gets the cached value, returning null if expires.
*/
public Object get()
{
if (Alarm.getCurrentTime() < createTime + expireInterval)
return value;
else {
Object v = value;
value = null;
if (v instanceof CacheListener)
((CacheListener) v).removeEvent();
return null;
}
}
}