///////////////////////////////////////////////////////////////////////
#region Iteration Helper Methods
private static bool HasGoodAccessCounts(
DateTimeIntPair anyPair,
int minimumAccessCount,
int maximumAccessCount
)
{
if (anyPair != null)
{
int accessCount = anyPair.Y;
if ((maximumAccessCount >= 0) &&
(accessCount > maximumAccessCount))
{
return(true);
}
if ((minimumAccessCount >= 0) &&
(accessCount < minimumAccessCount))
{
return(false);
}
return(true);
}
return(false);
}
///////////////////////////////////////////////////////////////////////
private IEnumerable <TKey> GetBadKeys( /* O(N) */
IEnumerable <TKey> oldKeys,
int minimumAccessCount,
int maximumAccessCount,
int limit
)
{
List <TKey> keys = MaybeUseOldKeys(oldKeys);
if (accessed != null)
{
foreach (KeyValuePair <TKey, DateTimeIntPair> pair in accessed)
{
DateTimeIntPair anyPair = pair.Value;
if (!HasGoodAccessCounts(anyPair,
minimumAccessCount, maximumAccessCount))
{
if (keys == null)
{
keys = new List <TKey>();
}
keys.Add(pair.Key);
//
// NOTE: Are we now at -OR- over the limit?
// If so, stop now.
//
if ((limit != 0) && (keys.Count >= limit))
{
break;
}
}
}
}
return(keys);
}
///////////////////////////////////////////////////////////////////////
private void UpdateAccessed(
TKey key,
DateTime?dateTime,
bool add
)
{
if (key == null)
{
return;
}
//
// NOTE: Previous time this key was accessed, if any.
//
DateTime?oldDateTime = null;
if (accessed != null)
{
//
// NOTE: The date may be null here (i.e. it never expires).
//
DateTimeIntPair anyPair;
if (!accessed.TryGetValue(key, out anyPair))
{
if (add)
{
anyPair = DateTimeIntPair.Create(dateTime);
accessed.Add(key, anyPair);
}
}
else if (anyPair != null)
{
//
// NOTE: Only grab the old date if the key was added at
// a prior point.
//
oldDateTime = anyPair.X;
}
//
// NOTE: Update the access count for this key, updating the
// maximum access count seen so far if necessary.
//
if (anyPair != null)
{
int accessCount = anyPair.Touch(dateTime);
if (accessCount > maximumAccessCount)
{
maximumAccessCount = accessCount;
}
}
}
//
// BUGFIX: Even when not adding, the DateTime entry may need to be
// removed from this dictionary if it was just updated in
// the accessed dictionary; otherwise, things start to get
// badly out of sync.
//
if ((dateTime != null) && (keysAccessed != null))
{
if (oldDateTime != null)
{
Dictionary <TKey, object> oldKeys;
if (keysAccessed.TryGetValue(oldDateTime, out oldKeys) &&
(oldKeys != null) && oldKeys.Remove(key) &&
(oldKeys.Count == 0))
{
keysAccessed.Remove(oldDateTime);
}
}
if (add)
{
Dictionary <TKey, object> newKeys;
if (keysAccessed.TryGetValue(dateTime, out newKeys))
{
if (newKeys != null)
{
newKeys.Add(key, null);
}
else
{
newKeys = new Dictionary <TKey, object>(this.Comparer);
newKeys.Add(key, null);
keysAccessed[dateTime] = newKeys;
}
}
else
{
newKeys = new Dictionary <TKey, object>(this.Comparer);
newKeys.Add(key, null);
keysAccessed.Add(dateTime, newKeys);
}
}
}
}
