void addLastRead(ConnectionUDP conn)
 {
     lock (this)
     {
         if (!taskTable.ContainsKey(conn.connectId))
         {
             AckListTask at = new AckListTask(conn);
             taskTable.Add(conn.connectId, at);
         }
     }
 }
 void addAck(ConnectionUDP conn, int sequence)
 {
     lock (this)
     {
         if (!taskTable.ContainsKey(conn.connectId))
         {
             AckListTask at = new AckListTask(conn);
             taskTable.Add(conn.connectId, at);
         }
         AckListTask at1 = taskTable[conn.connectId];
         at1.addAck(sequence);
     }
 }