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/*
* This library is part of OpenCms -
* the Open Source Content Management System
*
* Copyright (C) Alkacon Software (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;
import org.opencms.main.CmsLog;
import org.apache.commons.logging.Log;
/**
* Low-level utility class used for waiting for an action performed by another thread.
*
* This is really a thin wrapper around the wait() and notifyAll() methods.
*/
public class CmsWaitHandle {
/** Logger instance for this class. */
private static final Log LOG = CmsLog.getLog(CmsWaitHandle.class);
/** Flag which indicates whether release has already been called. */
private boolean m_released;
/** Flag indicating whether the wait handle is single-use. */
private boolean m_singleUse;
/**
* Creates a reusable wait handle.
*/
public CmsWaitHandle() {
m_singleUse = false;
}
/**
* Creates a wait handle.
*
* The argument controls whether the wait handle will be single-use or reusable. The difference is that, for a single-use
* wait handle, all calls to enter() will return immediately after the first call to release(), while calling enter() on
* a reusable wait handle will always wait for the next release call.
*
* @param singleUse true if a single-use wait handle should be created
*/
public CmsWaitHandle(boolean singleUse) {
m_singleUse = singleUse;
}
/**
* Waits for a maximum of waitTime, but returns if another thread calls release().
*
* @param waitTime the maximum wait time
*/
public synchronized void enter(long waitTime) {
if (m_singleUse && m_released) {
return;
}
try {
wait(waitTime);
} catch (InterruptedException e) {
// should never happen, but log it just in case...
LOG.error(e.getLocalizedMessage(), e);
}
}
/**
* Releases all currently waiting threads.
*/
public synchronized void release() {
notifyAll();
m_released = true;
}
}