content: /*
   * Copyright 1999-2012 Alibaba Group.
   *  
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *  
   *      http://www.apache.org/licenses/LICENSE-2.0
   *  
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.alibaba.cobar.server.response;
  
  import com.alibaba.cobar.CobarServer;
  import com.alibaba.cobar.mysql.PacketUtil;
  import com.alibaba.cobar.net.FrontendConnection;
  import com.alibaba.cobar.net.mysql.ErrorPacket;
  import com.alibaba.cobar.net.mysql.OkPacket;
  
  /**
   * 加入了offline状态推送，用于心跳语句。
   * 
   * @author xianmao.hexm 2012-4-28
   */
  public class Ping {
  
      private static final ErrorPacket error = PacketUtil.getShutdown();
  
      public static void response(FrontendConnection c) {
          if (CobarServer.getInstance().isOnline()) {
              c.write(c.writeToBuffer(OkPacket.OK, c.allocate()));
          } else {
              error.write(c);
          }
      }
  
  }
  