/*
* The Kuali Financial System, a comprehensive financial management system for higher education.
*
* Copyright 2005-2014 The Kuali Foundation
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.kuali.kfs.sys.monitor;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Simplifies writing tests which have to iterate in place until something happens (or until some timeout occurs and lets the test
* fail).
*/
abstract public class ChangeMonitor {
private static final Log LOG = LogFactory.getLog(ChangeMonitor.class);
/**
* Iterates, with pauseSeconds seconds between iterations, until either the given ChangeMonitor's valueChanged method returns
* true, or at least maxWaitSeconds seconds have passed.
*
* @param monitor ChangeMonitor instance which watches for whatever change your test is waiting for
* @param maxWaitSeconds
* @param pauseSeconds
* @return true if the the ChangeMonitor's valueChanged method returned true before time ran out
*/
public static boolean waitUntilChange(ChangeMonitor monitor, int maxWaitSeconds, int pauseSeconds) throws Exception {
long maxWaitMs = maxWaitSeconds * 1000;
long pauseMs = pauseSeconds * 1000;
boolean valueChanged = false;
boolean interrupted = false;
long startTimeMs = System.currentTimeMillis();
long endTimeMs = startTimeMs + maxWaitMs;
Thread.sleep(pauseMs / 10); // the first time through, sleep a fraction of the specified time
valueChanged = monitor.valueChanged();
LOG.debug("starting wait loop");
while (!interrupted && !valueChanged && (System.currentTimeMillis() < endTimeMs)) {
try {
if (LOG.isDebugEnabled()) {
LOG.debug("sleeping for " + pauseMs + " ms");
}
Thread.sleep(pauseMs);
}
catch (InterruptedException e) {
interrupted = true;
}
LOG.debug("checking wait loop sentinel");
valueChanged = monitor.valueChanged();
}
LOG.debug("finished wait loop (" + valueChanged + ")");
return valueChanged;
}
/**
* @return true if the value being monitored has changed
*/
abstract public boolean valueChanged() throws Exception;
}