public object GetData(string key)
{
ValidateKey(key);
CacheItem cacheItemBeforeLock = null;
bool lockWasSuccessful = false;
do
{
lock (inMemoryCache.SyncRoot)
{
cacheItemBeforeLock = (CacheItem)inMemoryCache[key];
if (IsObjectInCache(cacheItemBeforeLock))
{
CachingServiceItemReadEvent.Fire(false);
return(null);
}
lockWasSuccessful = Monitor.TryEnter(cacheItemBeforeLock);
}
if (lockWasSuccessful == false)
{
Thread.Sleep(0);
}
} while (lockWasSuccessful == false);
try
{
if (cacheItemBeforeLock.HasExpired())
{
cacheItemBeforeLock.TouchedByUserAction(true);
backingStore.Remove(key); // Does exception safety matter here? We're removing it due to expiration or scavenging...
inMemoryCache.Remove(key);
RefreshActionInvoker.InvokeRefreshAction(cacheItemBeforeLock, CacheItemRemovedReason.Expired);
CachingServiceItemReadEvent.Fire(false);
CachingServiceItemTurnoverEvent.FireRemoveItems(1);
CachingServiceItemTurnoverEvent.SetItemsTotal(inMemoryCache.Count);
return(null);
}
backingStore.UpdateLastAccessedTime(cacheItemBeforeLock.Key, DateTime.Now); // Does exception safety matter here?
cacheItemBeforeLock.TouchedByUserAction(false);
CachingServiceItemReadEvent.Fire(true);
return(cacheItemBeforeLock.Value);
}
finally
{
Monitor.Exit(cacheItemBeforeLock);
}
}
public void Remove(string key, CacheItemRemovedReason removalReason)
{
ValidateKey(key);
CacheItem cacheItemBeforeLock = null;
bool lockWasSuccessful;
do
{
lock (inMemoryCache.SyncRoot)
{
cacheItemBeforeLock = (CacheItem)inMemoryCache[key];
if (IsObjectInCache(cacheItemBeforeLock))
{
return;
}
lockWasSuccessful = Monitor.TryEnter(cacheItemBeforeLock);
}
if (lockWasSuccessful == false)
{
Thread.Sleep(0);
}
} while (lockWasSuccessful == false);
try
{
cacheItemBeforeLock.TouchedByUserAction(true);
backingStore.Remove(key); // Does exception safety matter here? We're removing it due to expiration or scavenging...
inMemoryCache.Remove(key);
RefreshActionInvoker.InvokeRefreshAction(cacheItemBeforeLock, removalReason);
CachingServiceItemTurnoverEvent.FireRemoveItems(1);
CachingServiceItemTurnoverEvent.SetItemsTotal(inMemoryCache.Count);
}
finally
{
Monitor.Exit(cacheItemBeforeLock);
}
}
/// <devdoc>
/// There may still be thread safety issues in this class with respect to expirations
/// and scavenging, but I really doubt that either of those will be happening while
/// a Flush is in progress. It seems that the most likely scenario for a flush
/// to be called is at the very start of a program, or when absolutely nothing else
/// is going on. Calling flush in the middle of an application would seem to be
/// an "interesting" thing to do in normal circumstances.
/// </devdoc>
public void Flush()
{
RestartFlushAlgorithm:
lock (inMemoryCache.SyncRoot)
{
foreach (string key in inMemoryCache.Keys)
{
bool lockWasSuccessful = false;
CacheItem itemToRemove = (CacheItem)inMemoryCache[key];
try
{
if (lockWasSuccessful = Monitor.TryEnter(itemToRemove))
{
itemToRemove.TouchedByUserAction(true);
}
else
{
goto RestartFlushAlgorithm;
}
}
finally
{
if (lockWasSuccessful)
{
Monitor.Exit(itemToRemove);
}
}
}
int countBeforeFlushing = inMemoryCache.Count;
backingStore.Flush();
inMemoryCache.Clear();
CachingServiceItemTurnoverEvent.FireRemoveItems(countBeforeFlushing);
CachingServiceItemTurnoverEvent.SetItemsTotal(0);
CachingServiceCacheFlushedEvent.FireEvent();
}
}
private void FireCachingServiceItemTurnoverEventRemoveItems()
{
CachingServiceItemTurnoverEvent.FireRemoveItems(1);
}