private const int nrBags = 265; // based on 240 timeslices + 20 bags for ItemLimit + 5 bags empty buffer
public LifespanManager(FluidCache <T> owner, TimeSpan minAge, TimeSpan maxAge, GetNow getNow)
{
this.owner = owner;
int maxMS = Math.Min((int)maxAge.TotalMilliseconds, 12 * 60 * 60 * 1000); // max = 12 hours
this.minAge = minAge;
this.getNow = getNow;
this.maxAge = TimeSpan.FromMilliseconds(maxMS);
validatyCheckInterval = TimeSpan.FromMilliseconds(maxMS / 240.0); // max timeslice = 3 min
bagItemLimit = this.owner.Capacity / 20; // max 5% of capacity per bag
bags = new AgeBag <T> [nrBags];
for (int loop = nrBags - 1; loop >= 0; --loop)
{
bags[loop] = new AgeBag <T>();
}
OpenCurrentBag(getNow(), 0);
}
/// <summary>
/// Remove old items or items beyond capacity from LifespanMgr allowing them to be garbage collected
/// </summary>
/// <remarks>
/// Since we do not physically move items when touched we must check items in bag to determine if they should
/// be deleted or moved. Also items that were removed by setting value to null get removed now. Rremoving
/// an item from LifespanMgr allows it to be garbage collected. If removed item is retrieved by index prior
/// to GC then it will be readded to LifespanMgr.
/// </remarks>
private void CleanUp(DateTime now)
{
lock (syncObject)
{
int itemsAboveCapacity = Stats.Current - Stats.Capacity;
AgeBag <T> bag = bags[OldestBagIndex];
while (!HasProcessedAllBags && (AlmostOutOfBags || BagNeedsCleaning(bag, itemsAboveCapacity, now)))
{
itemsAboveCapacity = CleanBag(bag, itemsAboveCapacity);
++OldestBagIndex;
bag = bags[OldestBagIndex];
}
++CurrentBagIndex;
OpenBag(CurrentBagIndex);
EnsureIndexIsValid();
}
}
/// <summary>ready a new current AgeBag for use and close the previous one</summary>
private void OpenCurrentBag(DateTime now, int bagNumber)
{
lock (this)
{
// close last age bag
if (this.currentBag != null)
{
this.currentBag.StopTime = now;
}
// open new age bag for next time slice
currentBagIndex = bagNumber;
AgeBag <T> currentBag = bags[currentBagIndex % nrBags];
currentBag.StartTime = now;
currentBag.First = null;
this.currentBag = currentBag;
// reset counters for CheckValidity()
nextValidityCheck = now.Add(validatyCheckInterval);
itemsInCurrentBag = 0;
}
}
private bool BagNeedsCleaning(AgeBag <T> bag, int itemsAboveCapacity, DateTime now)
{
return(bag.HasExpired(maxAge, now) || (itemsAboveCapacity > 0 && bag.HasReachedMinimumAge(minAge, now)));
}