Re: [reSIProcate] Timers: why system time?

["Alexander Altshuler" <alt@xxxxxxxxx>]

Hi

Adam Roach wrote:
>You could be even more clever about it than that. Inserting a
>timer immediately before and after the rollover should get you there.
>That way, you have two timers every 49 days, 
>instead of one timer every minute. :)

Here is some code to SIMULATE such timers.
And we don't need to deal with real timers.

====<8==================================================
unsigned int
BaseTimerQueue::msTillNextTimer()
{
   UInt64 now;
   int nextWrapAround = Timer::msTillNextWrapAroundTimer( now );
   if (!mTimers.empty())
   {
      UInt64 next = mTimers.begin()->mWhen;
      if (now > next) 
      {
         return 0;
      }
      else
      {
         UInt64 ret64 = next - now;
         if ( ret64 > UInt64(nextWrapAround) )
         {
            return nextWrapAround;
         }
         else
         { 
            int ret = int(ret64);
            return ret;
         }
      }
   }
   else
   {
      return nextWrapAround;
   }
}
// now is returned for efficiency reason
int
Timer::msTillNextWrapAroundTimer( UInt64& now )
{
        DWORD tick = ::GetTickCount();
        if( ( tick > TIMER_BEGIN_SAFE_RANGE ) && ( tick <
TIMER_END_SAFE_RANGE ) )
        {
                LARGE_INTEGER ret;
                ret.HighPart = mWrapCounter;
                ret.LowPart = tick;
                now = (UInt64)ret.QuadPart;
                DWORD msTillNextTimer = TIMER_END_SAFE_RANGE - tick;
                if( msTillNextTimer > DWORD(INT_MAX) )
                {
                        return INT_MAX;
                }
                return int(msTillNextTimer);
        }
        Lock lock( mWrapCounterMutex );
        if( mPrevTick > tick )
        {
                mWrapCounter++;
        }
        mPrevTick = tick;
        LARGE_INTEGER ret;
        ret.HighPart = mWrapCounter;
        ret.LowPart = tick;
        now = (UInt64)ret.QuadPart;
        if( tick > TIMER_END_SAFE_RANGE )
        {
                        return int( 0xffffffff - tick );                
        }
        // tick > 0 && tick < TIMER_BEGIN_SAFE_RANGE
        return INT_MAX;
}

====<8==================================================
-----Original Message-----
From: Adam Roach [mailto:adam@xxxxxxxxxxx] 
Sent: Friday, October 31, 2008 10:27 PM
To: Byron Campen
Cc: Alexander; 'resiprocate-devel'
Subject: Re: [reSIProcate] Timers: why system time?

Byron Campen wrote:
>     So, maybe on win32 we need to have something call getTimeMs() 
> every minute? A heartbeat timer of some sort?

You could be even more clever about it than that. Inserting a timer 
immediately before and after the rollover should get you there. That 
way, you have two timers every 49 days, instead of one timer every 
minute. :)

UInt64 timer1Time = 0x00000000FFFFFFF0ui64 | (Timer::getTimeMs() & 
0xFFFFFFFF00000000ui64);
UInt64 timer2Time = timer1 + 33;

Then, all you need is a new Timer constructor that takes an absolute 
time instead of a relative one.