content: /*
   * This library is part of OpenCms -
   * the Open Source Content Management System
   *
   * Copyright (C) Alkacon Software (https://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: https://www.alkacon.com
   *
   * For further information about OpenCms, please see the
   * project website: https://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.gwt.client.util;
  
  import java.util.HashSet;
  import java.util.Set;
  
  /**
   * Helper class used to perform an action when multiple asynchronous tasks have finished.<p>
   *
   * To use this, first, for every action, add a token which uniquely identifies the action. Remove the corresponding
   * token when the action is finished. When all tokens are removed, the final action will be executed.<p>
   */
  public class CmsAsyncJoinHandler {
  
      /** The action to perform when all tokens have been removed. */
      private Runnable m_joinAction;
  
      /** The set of tokens. */
      protected Set<Object> m_tokens = new HashSet<Object>();
  
      /**
       * Creates a new instance.<p>
       *
       * @param joinAction the final action to execute
       */
      public CmsAsyncJoinHandler(Runnable joinAction) {
  
          m_joinAction = joinAction;
      }
  
      /**
       * Adds tokens.<p>
       *
       * @param tokens the tokens to add
       */
      public void addTokens(Object... tokens) {
  
          for (Object token : tokens) {
              m_tokens.add(token);
          }
      }
  
      /**
       * Removes a token.<p>
       *
       * When all tokens have been removed, the final action is executed.<p>
       *
       * @param token the token to remove
       */
      public void removeToken(Object token) {
  
          m_tokens.remove(token);
          if (m_tokens.isEmpty()) {
              if (m_joinAction != null) {
                  m_joinAction.run();
              }
          }
      }
  
  }
  