/*
* This file is part of LibrePlan
*
* Copyright (C) 2010-2011 Igalia, S.L.
*
* 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.zkoss.ganttz.util;
/**
* <p>
* It marks the start and the end part of a potentially reentering execution
* using a {@link ThreadLocal} variable. For example, some method execution can
* eventually be called again. When that methods is called we want to know if
* it's called within the execution of itself or from the outside. I.e., it's
* useful to do different things depending if the execution is already being
* done or entering in it.
* </p>
*
* <p>
* It can detect if it's already executing or not. If it is,
* {@link IReentranceCases#ifAlreadyInside()} is called, otherwise
* {@link IReentranceCases#ifNewEntrance()} is called.
* </p>
*
* @author Óscar González Fernández <ogfernandez@gmail.com>
*/
public class ReentranceGuard {
public interface IReentranceCases {
public void ifNewEntrance();
public void ifAlreadyInside();
}
private final ThreadLocal<Boolean> inside = new ThreadLocal<Boolean>() {
protected Boolean initialValue() {
return false;
};
};
public void entranceRequested(IReentranceCases reentranceCases) {
if (inside.get()) {
reentranceCases.ifAlreadyInside();
return;
}
inside.set(true);
try {
reentranceCases.ifNewEntrance();
} finally {
inside.set(false);
}
}
}