public IAsyncTyrantCache GetAsyncCacheFor(HttpContext context, IAsyncResponsePlan plan)
{
IAsyncTyrantCache defaultCache = null;
//Grab the last cache that claims it can process the request.
foreach (IAsyncTyrantCache cache in c.Plugins.GetAll <IAsyncTyrantCache>())
{
if (cache.CanProcess(context, plan))
{
defaultCache = cache;
}
}
return(defaultCache);
}
/// <summary>
/// Generates the resized image to disk (if needed), then rewrites the request to that location.
/// Perform 404 checking before calling this method. Assumes file exists.
/// Called during PostAuthorizeRequest
/// </summary>
/// <param name="context"></param>
/// <param name="ra"></param>
/// <param name="vf"></param>
protected virtual async Task HandleRequest(HttpContext context, HttpModuleRequestAssistant ra, IVirtualFileAsync vf)
{
if (!ra.CachingIndicated && !ra.ProcessingIndicated)
{
ra.ApplyRewrittenPath(); //This is needed for both physical and virtual files; only makes changes if needed.
if (vf != null)
{
ra.AssignSFH(); //Virtual files are not served in .NET 4.
}
return;
}
//Communicate to the MVC plugin this request should not be affected by the UrlRoutingModule.
context.Items[conf.StopRoutingKey] = true;
context.Items[conf.ResponseArgsKey] = ""; //We are handling the request
ra.EstimateResponseInfo();
//Build CacheEventArgs
var e = new AsyncResponsePlan();
var modDate = (vf == null) ? System.IO.File.GetLastWriteTimeUtc(ra.RewrittenMappedPath) :
(vf is IVirtualFileWithModifiedDateAsync ? await((IVirtualFileWithModifiedDateAsync)vf).GetModifiedDateUTCAsync() : DateTime.MinValue);
e.RequestCachingKey = ra.GenerateRequestCachingKey(modDate);
var settings = new ResizeSettings(ra.RewrittenInstructions);
e.RewrittenQuerystring = settings;
e.EstimatedContentType = ra.EstimatedContentType;
e.EstimatedFileExtension = ra.EstimatedFileExtension;
//A delegate for accessing the source file
e.OpenSourceStreamAsync = async delegate()
{
return((vf != null) ? await vf.OpenAsync() : File.Open(ra.RewrittenMappedPath, FileMode.Open, FileAccess.Read, FileShare.Read));
};
//Add delegate for writing the data stream
e.CreateAndWriteResultAsync = async delegate(System.IO.Stream stream, IAsyncResponsePlan plan)
{
//This runs on a cache miss or cache invalid. This delegate is preventing from running in more
//than one thread at a time for the specified cache key
try
{
if (!ra.ProcessingIndicated)
{
//Just duplicate the data
using (Stream source = await e.OpenSourceStreamAsync())
await source.CopyToAsync(stream); //4KiB buffer
}
else
{
MemoryStream inBuffer = null;
using (var sourceStream = vf != null ? await vf.OpenAsync() : File.Open(ra.RewrittenMappedPath, FileMode.Open, FileAccess.Read, FileShare.Read))
{
inBuffer = new MemoryStream(sourceStream.CanSeek ? (int)sourceStream.Length : 128 * 1024);
await sourceStream.CopyToAsync(inBuffer);
}
inBuffer.Seek(0, SeekOrigin.Begin);
var outBuffer = new MemoryStream(32 * 1024);
//Handle I/O portions of work asynchronously.
var j = new ImageJob
{
Instructions = new Instructions(settings),
SourcePathData = vf != null ? vf.VirtualPath : ra.RewrittenVirtualPath,
Dest = outBuffer,
Source = inBuffer
};
await conf.GetImageBuilder().BuildAsync(j, int.MaxValue, CancellationToken.None);
outBuffer.Seek(0, SeekOrigin.Begin);
await outBuffer.CopyToAsync(stream);
}
ra.FireJobSuccess();
//Catch not found exceptions
}
catch (System.IO.FileNotFoundException notFound)
{
if (notFound.Message.Contains(" assembly "))
{
throw; //If an assembly is missing, it should be a 500, not a 404
}
//This will be called later, if at all.
ra.FireMissing();
throw new ImageMissingException("The specified resource could not be located", "File not found", notFound);
}
catch (System.IO.DirectoryNotFoundException notFound)
{
ra.FireMissing();
throw new ImageMissingException("The specified resource could not be located", "File not found", notFound);
}
catch (Exception ex)
{
ra.FireJobException(ex);
throw;
}
};
//All bad from here down....
context.Items[conf.ResponseArgsKey] = e; //store in context items
//Fire events (for client-side caching plugins)
conf.FirePreHandleImageAsync(this, context, e);
//Pass the rest of the work off to the caching module. It will handle rewriting/redirecting and everything.
//We handle request headers based on what is found in context.Items
IAsyncTyrantCache cache = conf.GetAsyncCacheFor(context, e);
//Verify we have a caching system
if (cache == null)
{
throw new ImageProcessingException("Image Resizer: No async caching plugin was found for the request");
}
await cache.ProcessAsync(context, e);
}
