/*
* 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 Software Foundation, Inc.
* 59 Temple Place, Suite 330
* Boston, MA 02111-1307 USA
*
* @author Scott Ferguson
*/
package com.caucho.make;
import com.caucho.loader.Environment;
import com.caucho.util.Alarm;
import com.caucho.vfs.Dependency;
/**
* A cached dependency only checks the dependency at an interval.
*/
abstract public class CachedDependency implements Dependency {
private long _checkInterval;
private long _lastCheckTime;
private boolean _isModified;
public CachedDependency()
{
_checkInterval = Environment.getDependencyCheckInterval();
}
/**
* Gets the check interval.
*/
public long getCheckInterval()
{
return _checkInterval;
}
/**
* Gets the check interval.
*/
public void setCheckInterval(long checkInterval)
{
_checkInterval = checkInterval;
}
/**
* Returns true if the underlying resource has changed.
*/
public final boolean isModified()
{
long now = Alarm.getCurrentTime();
if (now <= _lastCheckTime + _checkInterval)
return _isModified;
synchronized (this) {
now = Alarm.getCurrentTime();
if (now <= _lastCheckTime + _checkInterval)
return _isModified;
_lastCheckTime = now;
}
_isModified = isModifiedImpl();
return _isModified;
}
/**
* Returns true if the underlying resource has changed.
*/
abstract public boolean isModifiedImpl();
}