/// <summary>
/// Gets an item with a specified key from the HttpRuntime.Cache.
/// </summary>
/// <param name="key">The cache key.</param>
/// <param name="loadObj">The delegate returning the item to insert into cache when it doesn't exist.</param>
/// <param name="priority">The priority.</param>
/// <param name="autoInsertDependency">If set to true, a dependency will be automatically created when no cache
/// dependency is currently set. If this value is false and you try to retrieve an item from cache that was not added
/// first, this method will return null.</param>
/// <returns>
/// The cached item when present at HttpRuntime.Cache, the loadObj delegate (which re-adds the item
/// at cache) when the item can't be found at cache, null if the cache item dependency doesn't exist and autoInsertDependency
/// is set to false or the loadObj delegate returned null.
/// </returns>
public static object GetCacheItem(string key, ReloadObjectAtCache loadObj, CacheItemPriority priority, bool autoInsertDependency)
{
object fetchedItem = null;
switch (ClusteredCacheController.ClusteredCachingMode)
{
case ClusteredCachingMode.ServiceBroker:
#region service broker
lock (_CacheLock)
{
if (HttpRuntime.Cache[key] == null)
{
// check whether we have a dependency...
string dependencyId = GetDependencyIDFromCacheKey(key);
if (!string.IsNullOrEmpty(dependencyId) || autoInsertDependency)
{ // we actually have a dependency, so refresh the cache...
try { fetchedItem = loadObj(); }
catch (Exception err) { throw new CachingException("Error at loading object into cache. See the inner exception for further details.", err); }
if (fetchedItem == null)
{ // we can't insert null as an object, so simply return null.
return(null);
}
HttpRuntime.Cache.Insert(key, fetchedItem, null, Cache.NoAbsoluteExpiration, Cache.NoSlidingExpiration, priority, null);
return(fetchedItem);
}
else
{ // this key doesn't exist and there is no associated dependency, so return null...
return(null);
}
}
return(HttpRuntime.Cache[key]);
}
#endregion
case ClusteredCachingMode.CheckAtRequest:
#region Check at request
long synchTicks = -1;
lock (_CacheLock)
{
ClusteredCachingSynchronizationStatus status = IsUpToDate(key, out synchTicks);
switch (status)
{
case ClusteredCachingSynchronizationStatus.UpToDate:
if (HttpRuntime.Cache[key] == null)
{
try { fetchedItem = loadObj(); }
catch (Exception err) { throw new CachingException("Error at loading object into cache. See the inner exception for further details.", err); }
if (fetchedItem == null)
{ // we can't insert null as an object, so simply return null.
return(null);
}
HttpRuntime.Cache.Insert(key, fetchedItem, null, Cache.NoAbsoluteExpiration, Cache.NoSlidingExpiration, priority, null);
return(fetchedItem);
}
return(HttpRuntime.Cache[key]);
case ClusteredCachingSynchronizationStatus.OutOfDate:
CheckAtRequestDependencies[key] = GetCheckAtRequestInfo(synchTicks);
HttpRuntime.Cache.Remove(key);
try { fetchedItem = loadObj(); }
catch (Exception err) { throw new CachingException("Error at loading object into cache. See the inner exception for further details.", err); }
if (fetchedItem == null)
{ // we can't insert null as an object, so simply return null.
return(null);
}
HttpRuntime.Cache.Insert(key, fetchedItem, null, Cache.NoAbsoluteExpiration, Cache.NoSlidingExpiration, priority, null);
return(fetchedItem);
case ClusteredCachingSynchronizationStatus.NotFound:
CheckAtRequestDependencies.Add(key, GetCheckAtRequestInfo(synchTicks));
HttpRuntime.Cache.Remove(key);
try { fetchedItem = loadObj(); }
catch (Exception err) { throw new CachingException("Error at loading object into cache. See the inner exception for further details.", err); }
if (fetchedItem == null)
{ // we can't insert null as an object, so simply return null.
return(null);
}
HttpRuntime.Cache.Insert(key, fetchedItem, null, Cache.NoAbsoluteExpiration, Cache.NoSlidingExpiration, priority, null);
return(fetchedItem);
case ClusteredCachingSynchronizationStatus.RemovedFromCollection:
if (autoInsertDependency)
{
try { fetchedItem = loadObj(); }
catch (Exception err) { throw new CachingException("Error at loading object into cache. See the inner exception for further details.", err); }
AddCacheItem(key, fetchedItem, priority);
return(fetchedItem);
}
else
{
HttpRuntime.Cache.Remove(key);
CheckAtRequestDependencies.Remove(key);
return(null);
}
}
break;
}
#endregion
}
return(null);
}
/// <summary>
/// Gets an item with a specified key from the HttpRuntime.Cache.
/// </summary>
/// <param name="key">The cache key.</param>
/// <param name="loadObj">The delegate returning the item to insert into cache when it doesn't exist.</param>
/// <param name="priority">The priority.</param>
/// <returns>
/// The cached item when present at HttpRuntime.Cache, the loadObj delegate (which re-adds the item
/// at cache) when the item can't be found at cache, null if the cache item dependency doesn't exist
/// or the loadObj delegate returned null.
/// </returns>
public static object GetCacheItem(string key, ReloadObjectAtCache loadObj, CacheItemPriority priority)
{
return(GetCacheItem(key, loadObj, priority, false));
}