org.opencms.util.CmsExpiringValue Maven / Gradle / Ivy
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/*
* This library is part of OpenCms -
* the Open Source Content Management System
*
* Copyright (c) Alkacon Software GmbH & Co. KG (http://www.alkacon.com)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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. See the GNU
* Lesser General Public License for more details.
*
* For further information about Alkacon Software, please see the
* company website: http://www.alkacon.com
*
* For further information about OpenCms, please see the
* project website: http://www.opencms.org
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package org.opencms.util;
/**
* Simple utility class for caching a single value with a given cache expiration time.
*
* If the time between the last write operation and a read operation is longer than the expiration time,
* null will be returned from the read operation.
*
* @param the type of the cached value
*/
public class CmsExpiringValue {
/** The cached value. */
private T m_value;
/** Last time the value was set. */
private long m_lastUpdate;
/** The expiration time. */
private long m_expirationTime;
/**
* Creates a new instance.
*
* @param expirationTime the expiration time in milliseconds
*/
public CmsExpiringValue(long expirationTime) {
m_expirationTime = expirationTime;
}
/**
* Gets the cached value.
*
* Returns null if the last update was longer ago than the expiration time.
*
* @return the cached value
*/
public synchronized T get() {
if ((System.currentTimeMillis() - m_lastUpdate) > m_expirationTime) {
return null;
}
return m_value;
}
/**
* Sets the cached value.
*
* @param value the cached value
*/
public synchronized void set(T value) {
m_lastUpdate = System.currentTimeMillis();
m_value = value;
}
}