/// <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 (this)
{
int itemsAboveCapacity = Stats.Current - Stats.Capacity;
AgeBag <T> bag = bags[OldestBagIndex];
while (AlmostOutOfBags || bag.HasExpired(maxAge, now) ||
(itemsAboveCapacity > 0 && bag.HasReachedMinimumAge(minAge, now)))
{
// cache is still too big / old so remove oldest bag
Node <T> node = bag.First;
bag.First = null;
while (node != null)
{
Node <T> next = node.Next;
node.Next = null;
if (node.Value != null && node.Bag != null)
{
if (node.Bag == bag)
{
// item has not been touched since bag was closed, so remove it from LifespanMgr
++itemsAboveCapacity;
node.Remove();
}
else
{
// item has been touched and should be moved to correct age bag now
node.Next = node.Bag.First;
node.Bag.First = node;
}
}
node = next;
}
bag = bags[++OldestBagIndex];
if (HasProcessedAllBags)
{
break;
}
}
OpenBag(++CurrentBagIndex);
EnsureIndexIsValid();
}
}
private bool BagNeedsCleaning(AgeBag <T> bag, int itemsAboveCapacity, DateTime now)
{
return(bag.HasExpired(maxAge, now) || (itemsAboveCapacity > 0 && bag.HasReachedMinimumAge(minAge, now)));
}