ContextualTask.java

/*
 * Copyright (C) 2009 eXo Platform SAS.
 *
 * This 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 software 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.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.exoplatform.commons.chromattic;

/**
 * @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
 * @version $Revision$
 * @param <V> the return type value
 */
public abstract class ContextualTask<V> {

    /**
     * Executes a task within a context from the specified life cycle. If an existing context already exists then this context
     * is used otherwise a context is managed for the duration of the {@link #execute(SessionContext)} method.
     *
     * @param lifeCycle the life cycle
     * @return a value
     */
    public final V executeWith(ChromatticLifeCycle lifeCycle) {
        SessionContext context = lifeCycle.getContext(true);
        if (context == null) {
            context = lifeCycle.openContext();
            try {
                return execute(context);
            } finally {
                lifeCycle.closeContext(true);
            }
        } else {
            return execute(context);
        }
    }

    /**
     * Implementor must provide the task logic here.
     *
     * @param context the context
     * @return a value
     */
    protected abstract V execute(SessionContext context);

}