[reSIProcate] Timers: why system time?

[Alexander Altshuler]

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 at nostrum.com] 
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.