/// <summary>
/// Gets an object from the cache or creates it if it doesnt exist
/// </summary>
/// <param name="key">key to item</param>
/// <param name="expire">Expire this item after this much time. -1 for NEVER</param>
/// <param name="f">Factory method if key doesnt exist</param>
/// <returns></returns>
public object Get(string key, TimeSpan expire, Func <object> f)
{
CacheItem item = backend.Get(key);
if (item == null)
{
if (f != null)
{
object val = f();
item = new CacheItem(key, val);
// anything less than 0 is NEVER
if (expire.Ticks < 0)
{
item.Stats.Expire = DateTime.MaxValue;
}
else
{
item.Stats.Expire = item.Stats.Created + expire;
}
backend.Set(item);
}
}
if (item == null)
{
return(null);
}
// item is expired..
if (item.Stats.Expire <= DateTime.Now)
{
// recreate it..
if (f != null)
{
object val = f();
item = new CacheItem(key, val);
backend.Set(item);
}
}
// anything less than 0 is NEVER
if (expire.Ticks < 0)
{
item.Stats.Expire = DateTime.MaxValue;
}
else
{
item.Stats.Expire = item.Stats.Created + expire;
}
// update access statistics for the item
backend.Touch(item);
return(item.Value);
}
/// <summary>
/// Prune old entries from the cache
/// </summary>
protected void Prune()
{
if (Full == false)
{
return;
}
// ascending order (ie, oldest first)
var tmp = data.OrderBy(x => x.Value.Stats.LastAccessTime);
foreach (KeyValuePair <string, CacheItem> c in tmp)
{
CacheItem ci = Remove(c.Key);
if (fallback != null)
{
fallback.Set(ci);
}
// dont need to remove any more
if (Full == false)
{
break;
}
}
}
public CacheItem Remove(string key)
{
// TODO: get the cacheItem first..
FileEntry e;
CacheItem ret = null;
pruneLock.EnterWriteLock();
try
{
if (data.TryGetValue(key, out e))
{
Console.WriteLine("Removing " + key);
ret = Deserialize(e);
data.Remove(key);
// place expired item into the fallback,
// if we have one
if (this.fallback != null)
{
fallback.Set(ret);
}
}
}
finally
{
pruneLock.ExitWriteLock();
}
if (e != null)
{
MarkFreeSpace(e.Segment);
}
return(ret);
}
