ImageResizer - Need to remove images that are in the image cache

Question

I use the ImageResizer tool with the DiskCache plugin. We use Azure blob storage to store images and a custom plugin to serve those images within the resizer code. Something went awry and some of the blobs have been deleted, but are cached in the DiskCache in the resizer.

I need to be able to build the hash key to be able to identify the images in the cache. I tried building the key from what I can see in the code, but the string returned does not yield a file in the cache

var vp = ResolveAppRelativeAssumeAppRelative(virtualPath);
var qs = PathUtils.BuildQueryString(queryString).Replace("&red_dot=true", "");

var blob = new Blob(this, virtualPath, queryString);
var modified = blob.ModifiedDateUTC;

var cachekey = string.Format("{0}{1}|{2}", vp, qs, blob.GetModifiedDateUTCAsync().Result.Ticks.ToString(NumberFormatInfo.InvariantInfo));

var relativePath = new UrlHasher().hash(cachekey, 4096, "/");

How can I query the cache to see if the images are still cached and then delete them if they do not exist in the blob storage account?

Note: I have tried to use the AzureReader2 plugin and it doesn't work for us at the moment.

Answer 1

Custom plugins are responsible for controlling access to cached files.

If you want to see where an active request is being cached, check out HttpContext.Current.Items["FinalCachedFile"] during the EndRequest phase of the request. You could do this with an event handler.