/// <summary>
/// Prune cache.
/// </summary>
void Prune(object _discard, System.Timers.ElapsedEventArgs _2)
{
if (disposed)
{
return; // dumbness with timers
}
if (!Atomic.Lock(ref prune_in_progress))
{
return; // only one instance.
}
try
{
if (Items.Count <= MinCache)
{
return; // just don't bother
}
if (Items.Count <= AbsoluteCapacity && CacheEvictStrategy == EvictStrategy.LeastUsed)
{
return;
}
var list = Items.Values.ToList(); // would be nice to cache this list
list.Sort((CacheItem <TKey, TValue> x, CacheItem <TKey, TValue> y) =>
{
if (CacheEvictStrategy == EvictStrategy.LeastRecent)
{
if (x.Access < y.Access)
{
return(-1);
}
if (x.Access > y.Access)
{
return(1);
}
// Both have equal at this point
if (x.Desirability < y.Desirability)
{
return(-1);
}
if (x.Desirability > y.Desirability)
{
return(1);
}
}
else // EvictStrategy.LeastUsed
{
if (x.Desirability < y.Desirability)
{
return(-1);
}
if (x.Desirability > y.Desirability)
{
return(1);
}
// Both have equal at this point
if (x.Access < y.Access)
{
return(-1);
}
if (x.Access > y.Access)
{
return(1);
}
}
return(0);
});
while (Items.Count > AbsoluteCapacity)
{
var bu = list[0];
var key = bu.AccessKey;
Items.TryRemove(key, out _);
list.Remove(bu);
}
var deleteItem = new Action <TKey>(
(TKey key) =>
{
//Debug.WriteLine($"MKAh.SimpleCache removing {bi:N1} min old item.");
if (Items.TryRemove(key, out var item))
{
list.Remove(item);
}
}
);
var now = DateTimeOffset.UtcNow;
while (list.Count > 0)
{
var bu = list[0];
double bi = now.Since(bu.Access).TotalMinutes;
if (CacheEvictStrategy == EvictStrategy.LeastRecent)
{
if (bi > MaxAge)
{
deleteItem(bu.AccessKey);
}
else
{
break;
}
}
else // .LeastUsed
{
if (bi > MinAge)
{
deleteItem(bu.AccessKey);
}
else
{
break;
}
}
}
}
finally
{
Atomic.Unlock(ref prune_in_progress);
}
}