/// <summary>
/// Thread that ages the cache and purges expired entries.
/// </summary>
private void CacheThread()
{
// Don't ever exit.
while (true)
{
try
{
lock (typeof(NodeCache))
{
// TODO: Remove
// log.Debug( "Cache efficency = {0}%, Current count = {1}, Access Count = {2}, Hit Count = {3}", ( ( accessCount > 0 ) ? ( hitCount / accessCount ) * 100 : 0 ), cacheTable.Count, accessCount, hitCount );
ArrayList keyList = new ArrayList(cacheTable.Keys);
foreach (string key in keyList)
{
NodeCacheEntry entry = cacheTable[key] as NodeCacheEntry;
if (!entry.IsValid)
{
cacheTable.Remove(key);
}
}
}
Thread.Sleep(cachePurgeTimeout);
}
catch (Exception ex)
{
log.Error(ex, "NodeCache Thread exception");
}
}
}
/// <summary>
/// Creates a new entry and adds it to the head of the list.
/// </summary>
public ICacheEntry <TKey, TValue> NewEntry(TKey key, TValue value)
{
var node = new LinkedListNode <TKey>(key);
var entry = new NodeCacheEntry <TKey, TValue>()
{
Key = key, Value = value, Node = node
};
list.AddFirst(node);
return(entry);
}
/// <summary>
/// Adds a node object to the cache.
/// </summary>
/// <param name="collection">The collection that the node object belongs to.</param>
/// <param name="node">The node object to add to the cache.</param>
public void Add(Collection collection, Node node)
{
// Make sure that the node can be cached.
if (IsCacheable(collection, node))
{
// Generate a key to use with the cache table.
string key = CreateKey(collection.ID, node.ID);
lock (typeof(NodeCache))
{
// Check to see if the entry is already in the cache.
NodeCacheEntry entry = cacheTable[key] as NodeCacheEntry;
if (entry == null)
{
cacheTable[key] = new NodeCacheEntry(node.Properties.ToString(), cacheTimeToLive);
}
else
{
entry.Value = node.Properties.ToString();
}
}
}
}
/// <summary>
/// Gets a node object from the cache table.
/// </summary>
/// <param name="collectionID">The ID of the collection that the node belongs to.</param>
/// <param name="nodeID">The ID of the node object.</param>
/// <returns>A node object if the ID exists in the cache. Otherwise a null is returned.</returns>
public Node Get(string collectionID, string nodeID)
{
string cacheValue = null;
string key = CreateKey(collectionID, nodeID);
lock (typeof(NodeCache))
{
// TODO: Remove
accessCount++;
NodeCacheEntry entry = cacheTable[key] as NodeCacheEntry;
if (entry != null)
{
// Keep this entry in the cache.
entry.UpdateExpirationTime();
cacheValue = entry.Value as string;
// TODO: Remove
hitCount++;
}
}
return((cacheValue != null) ? NodeFromString(cacheValue) : null);
}
