/// <summary>
/// Retrieves the file corresponding to the key, if it is in the cache.
/// Also touches the item, thus changing its LRU timestamp. If the file
/// is not present in the file cache, returns null.
/// <para />
/// This should NOT be called on the UI thread.
/// </summary>
/// <param name="key">The key to check.</param>
/// <returns>
/// The resource if present in cache, otherwise null.
/// </returns>
public IBinaryResource GetResource(ICacheKey key)
{
SettableCacheEvent cacheEvent = SettableCacheEvent
.Obtain()
.SetCacheKey(key);
try
{
lock (_lock)
{
IBinaryResource resource = null;
IList <string> resourceIds = CacheKeyUtil.GetResourceIds(key);
string resourceId = default(string);
foreach (var entry in resourceIds)
{
resourceId = entry;
cacheEvent.SetResourceId(resourceId);
resource = _storage.GetResource(resourceId, key);
if (resource != null)
{
break;
}
}
if (resource == null)
{
_cacheEventListener.OnMiss(cacheEvent);
_resourceIndex.Remove(resourceId);
}
else
{
_cacheEventListener.OnHit(cacheEvent);
_resourceIndex.Add(resourceId);
}
return(resource);
}
}
catch (IOException ioe)
{
_cacheErrorLogger.LogError(
CacheErrorCategory.GENERIC_IO,
typeof(DiskStorageCache),
"GetResource");
cacheEvent.SetException(ioe);
_cacheEventListener.OnReadException(cacheEvent);
return(null);
}
finally
{
cacheEvent.Recycle();
}
}
internal void CreateRootDirectoryIfNecessary(FileSystemInfo rootDirectory)
{
try
{
FileUtils.Mkdirs(rootDirectory);
}
catch (CreateDirectoryException)
{
_cacheErrorLogger.LogError(
CacheErrorCategory.WRITE_CREATE_DIR,
typeof(DynamicDefaultDiskStorage),
"createRootDirectoryIfNecessary");
throw;
}
Debug.WriteLine($"Created cache directory { rootDirectory.FullName }");
}
private static bool CheckExternal(FileSystemInfo directory, ICacheErrorLogger cacheErrorLogger)
{
try
{
// Get the logical root folder for all external storage devices.
StorageFolder externalDevices = KnownFolders.RemovableDevices;
if (directory.FullName.Contains(externalDevices.Path))
{
return(true);
}
}
catch (Exception)
{
cacheErrorLogger.LogError(
CacheErrorCategory.OTHER,
typeof(DefaultDiskStorage),
"Failed to read folder to check if external: " + directory.Name);
}
return(false);
}