release/src/router/mysql/storage/ndb/src/kernel/blocks/qmgr/timer.hpp

   1 /* Copyright (c) 2003, 2005 MySQL AB
   2
   3    This program is free software; you can redistribute it and/or modify
   4    it under the terms of the GNU General Public License as published by
   5    the Free Software Foundation; version 2 of the License.
   6
   7    This program is distributed in the hope that it will be useful,
   8    but WITHOUT ANY WARRANTY; without even the implied warranty of
   9    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10    GNU General Public License for more details.
  11
  12    You should have received a copy of the GNU General Public License
  13    along with this program; if not, write to the Free Software
  14    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA */
  15
  16 /**
  17  *  @class Timer
  18  *  @brief A timer class that can't be fooled by NTP:ing the system clock to old time
  19  */
  20 class Timer {
  21 public:
  22   Timer() {
  23     m_delay = 10;
  24   };
  25
  26   Timer(NDB_TICKS delay_time) {
  27     m_delay = delay_time;
  28   }
  29
  30   /**
  31    *  Set/Get alarm time of timer
  32    */
  33   inline void       setDelay(NDB_TICKS delay_time) { m_delay = delay_time;  }
  34   inline NDB_TICKS  getDelay()                     { return m_delay; }
  35
  36   /**
  37    *  Start timer
  38    */
  39   inline void reset() {
  40     m_current_time = NdbTick_CurrentMillisecond();
  41     m_alarm_time = m_current_time + m_delay;
  42   }
  43
  44   /**
  45    *  Check for alarm
  46    */
  47   inline bool check() { return check(NdbTick_CurrentMillisecond()); }
  48
  49   inline bool check(NDB_TICKS check_time) {
  50     /**
  51      *  Standard alarm check
  52      */
  53     if (check_time > m_alarm_time) return true;
  54
  55     /**
  56      *  Time progressing, but it is not alarm time yet
  57      */
  58     if (check_time >= m_current_time) return false;
  59
  60     /**
  61      *  Time has moved backwards
  62      */
  63     reset();
  64     return false;
  65   }
  66
  67 private:
  68   NDB_TICKS m_current_time;
  69   NDB_TICKS m_alarm_time;
  70   NDB_TICKS m_delay;
  71 };