/// <summary>
/// Tries to lock the correlated todo instance with the specified scheduled date, true if locked, false, otherwise.
/// Takes lock IF not enqueue, false otherwise
/// </summary>
private bool tryLockCorrelatedProcessing(string key, DateTime sd)
{
if (key == null)
{
key = string.Empty;
}
lock (m_CorrelationLocker)
{
_lck lck;
if (!m_CorrelationLocker.TryGetValue(key, out lck))
{
lck = new _lck {
Date = sd, IsEnqueue = 0, IsProc = 1
};
m_CorrelationLocker.Add(key, lck);
return(true);
}
if (lck.IsEnqueue == 0)
{
lck.IsProc++;
if (sd > lck.Date)
{
lck.Date = sd;
}
return(true);
}
return(false);//lock is enqueue type
}
}
/*
* Locking works as follows:
* ---------------------------
* All locking is done per CorrelationKey (different CorrelationKey do not inter-lock at all)
* Within the same key:
*
* Any existing Enqueue lock blocks another Enqueue until existing is released
* Any existing Enqueue lock returns FALSE for another Process until all Enqueue released
*
* Any existing Processing lock yields next date to Enqueue (+1 sec)
* Any Exisiting Processing lock shifts next Date if another Processing lock is further advanced in time
*
*
* Enqueue lock is reentrant for the same thread.
* Processing lock is reentrant regardless of thread ownership
*
*/
/// <summary>
/// Returns the point in time AFTER which the enqueue operation may fetch correlated todos
/// </summary>
private DateTime lockCorrelatedEnqueue(string key, DateTime sd)
{
if (key == null)
{
key = string.Empty;
}
var ct = Thread.CurrentThread;
uint spinCount = 0;
while (true)
{
lock (m_CorrelationLocker)
{
_lck lck;
if (!m_CorrelationLocker.TryGetValue(key, out lck))
{
lck = new _lck {
TEnqueue = ct, Date = sd, IsEnqueue = 1, IsProc = 0
};
m_CorrelationLocker.Add(key, lck);
return(sd);
}
if (lck.IsEnqueue == 0)
{
lck.IsEnqueue = 1;
lck.TEnqueue = ct;
return(lck.Date.AddSeconds(1));
}
if (lck.TEnqueue == ct)//if already acquired by this thread
{
lck.IsEnqueue++;
if (sd < lck.Date)
{
lck.Date = sd;
}
return(lck.Date);
}
}
if (spinCount < 100)
{
Thread.SpinWait(500);
}
else
{
Thread.Yield();
}
unchecked { spinCount++; }
}
}
