public FormattedImage Process(FormattedImage image, ILogger logger, IDictionary <string, string> commands) => image;
private async Task ProcessRequestAsync(HttpContext context, bool processRequest, IImageResolver sourceImageResolver, ImageContext imageContext, IDictionary <string, string> commands)
{
// Create a cache key based on all the components of the requested url
string uri = GetUri(context, commands);
string key = this.cacheHash.Create(uri, this.options.CachedNameLength);
ImageMetadata sourceImageMetadata = default;
if (processRequest)
{
// Lock any reads when a write is being done for the same key to prevent potential file locks.
using (await AsyncLock.ReaderLockAsync(key))
{
// Check to see if the cache contains this image
sourceImageMetadata = await sourceImageResolver.GetMetaDataAsync();
IImageCacheResolver cachedImageResolver = await this.cache.GetAsync(key);
if (cachedImageResolver != null)
{
ImageCacheMetadata cachedImageMetadata = await cachedImageResolver.GetMetaDataAsync();
if (cachedImageMetadata != default)
{
// Has the cached image expired or has the source image been updated?
if (cachedImageMetadata.SourceLastWriteTimeUtc == sourceImageMetadata.LastWriteTimeUtc &&
cachedImageMetadata.CacheLastWriteTimeUtc > DateTimeOffset.Now.AddDays(-this.options.MaxCacheDays))
{
// We're pulling the image from the cache.
using (Stream cachedBuffer = await cachedImageResolver.OpenReadAsync())
{
await this.SendResponseAsync(imageContext, key, cachedBuffer, cachedImageMetadata);
}
return;
}
}
}
}
// Not cached? Let's get it from the image resolver.
ChunkedMemoryStream outStream = null;
try
{
if (processRequest)
{
// Enter a write lock which locks writing and any reads for the same request.
// This reduces the overheads of unnecessary processing plus avoids file locks.
using (await AsyncLock.WriterLockAsync(key))
{
// No allocations here for inStream since we are passing the raw input stream.
// outStream allocation depends on the memory allocator used.
ImageCacheMetadata cachedImageMetadata = default;
outStream = new ChunkedMemoryStream();
using (Stream inStream = await sourceImageResolver.OpenReadAsync())
{
IImageFormat format;
// No commands? We simply copy the stream across.
if (commands.Count == 0)
{
format = Image.DetectFormat(this.options.Configuration, inStream);
await inStream.CopyToAsync(outStream);
}
else
{
using (var image = FormattedImage.Load(this.options.Configuration, inStream))
{
image.Process(this.logger, this.processors, commands);
this.options.OnBeforeSave?.Invoke(image);
image.Save(outStream);
format = image.Format;
}
}
// Check to see if the source metadata has a cachecontrol max-age value and use it to
// override the default max age from our options.
var maxAge = TimeSpan.FromDays(this.options.MaxBrowserCacheDays);
if (!sourceImageMetadata.CacheControlMaxAge.Equals(TimeSpan.MinValue))
{
maxAge = sourceImageMetadata.CacheControlMaxAge;
}
cachedImageMetadata = new ImageCacheMetadata(
sourceImageMetadata.LastWriteTimeUtc,
DateTime.UtcNow,
format.DefaultMimeType,
maxAge);
}
// Allow for any further optimization of the image. Always reset the position just in case.
outStream.Position = 0;
string contentType = cachedImageMetadata.ContentType;
string extension = this.formatUtilities.GetExtensionFromContentType(contentType);
this.options.OnProcessed?.Invoke(new ImageProcessingContext(context, outStream, commands, contentType, extension));
outStream.Position = 0;
// Save the image to the cache and send the response to the caller.
await this.cache.SetAsync(key, outStream, cachedImageMetadata);
await this.SendResponseAsync(imageContext, key, outStream, cachedImageMetadata);
}
}
}
catch (Exception ex)
{
// Log the error internally then rethrow.
// We don't call next here, the pipeline will automatically handle it
this.logger.LogImageProcessingFailed(imageContext.GetDisplayUrl(), ex);
throw;
}
finally
{
outStream?.Dispose();
}
}
}
/// <summary>
/// Performs operations upon the current request.
/// </summary>
/// <param name="context">The current HTTP request context</param>
/// <returns>The <see cref="Task"/></returns>
public async Task Invoke(HttpContext context)
{
IDictionary <string, string> commands = this.uriParser.ParseUriCommands(context);
this.options.OnValidate(new ImageValidationContext(context, commands, CommandParser.Instance));
if (!commands.Any() || !commands.Keys.Intersect(this.knownCommands).Any())
{
// Nothing to do. call the next delegate/middleware in the pipeline
await this.next(context);
return;
}
// Get the correct service for the request.
IImageResolver resolver = this.resolvers.FirstOrDefault(r => r.Match(context));
if (resolver == null || !await resolver.IsValidRequestAsync(context, this.logger))
{
// Nothing to do. call the next delegate/middleware in the pipeline
await this.next(context);
return;
}
string uri = context.Request.Path + QueryString.Create(commands);
string key = CacheHash.Create(uri, this.options.Configuration);
CachedInfo info = await this.cache.IsExpiredAsync(key, DateTime.UtcNow.AddDays(-this.options.MaxCacheDays));
var imageContext = new ImageContext(context, this.options);
if (!info.Expired)
{
// Image is a cached image. Return the correct response now.
await this.SendResponse(imageContext, key, info.LastModifiedUtc, null, (int)info.Length);
return;
}
// Not cached? Let's get it from the image resolver.
byte[] inBuffer = null;
byte[] outBuffer = null;
MemoryStream outStream = null;
try
{
inBuffer = await resolver.ResolveImageAsync(context, this.logger);
if (inBuffer == null || inBuffer.Length == 0)
{
// Log the error but let the pipeline handle the 404
this.logger.LogImageResolveFailed(imageContext.GetDisplayUrl());
await this.next(context);
return;
}
// No allocations here for inStream since we are passing the buffer.
// TODO: How to prevent the allocation in outStream? Passing a pooled buffer won't let stream grow if needed.
outStream = new MemoryStream();
using (var image = FormattedImage.Load(this.options.Configuration, inBuffer))
{
image.Process(this.logger, this.processors, commands);
image.Save(outStream);
}
// Allow for any further optimization of the image. Always reset the position just in case.
outStream.Position = 0;
this.options.OnProcessed(new ImageProcessingContext(context, outStream, Path.GetExtension(key)));
outStream.Position = 0;
int outLength = (int)outStream.Length;
// Copy the outstream to the pooled buffer.
outBuffer = BufferDataPool.Rent(outLength);
await outStream.ReadAsync(outBuffer, 0, outLength);
DateTimeOffset cachedDate = await this.cache.SetAsync(key, outBuffer, outLength);
await this.SendResponse(imageContext, key, cachedDate, outBuffer, outLength);
}
catch (Exception ex)
{
this.logger.LogImageProcessingFailed(imageContext.GetDisplayUrl(), ex);
}
finally
{
outStream?.Dispose();
// Buffer should have been rented in IImageResolver
BufferDataPool.Return(inBuffer);
BufferDataPool.Return(outBuffer);
}
}
/// <summary>
/// Loops through the available processors and updates the image if any match.
/// </summary>
/// <param name="source">The image to resize.</param>
/// <param name="logger">The type used for performing logging.</param>
/// <param name="processors">The collection of available processors.</param>
/// <param name="commands">The parsed collection of processing commands.</param>
/// <param name="parser">The command parser use for parting commands.</param>
/// <param name="culture">
/// The <see cref="CultureInfo"/> to use as the current parsing culture.
/// </param>
/// <returns>The <see cref="FormattedImage"/>.</returns>
public static FormattedImage Process(
this FormattedImage source,
ILogger logger,
IReadOnlyList <(int Index, IImageWebProcessor Processor)> processors,
