Custom Image Resolver

[tekguy]

Hello,

I recently upgraded to version 1.0.1 of the ImageSharp.Web nuget. I have two custom Image Providers (ProviderA, ProviderB).
Both ORIGINAL images I am grabbing updates the image every 5 seconds or so (think security cams).

I am trying to figure out a way to set the max cache for each provider (one for 10 seconds, one for 1 min as an example). Here is the code I am using in ProviderA:

public async Task<ImageMetadata> GetMetaDataAsync()
{
    // just randomly setting a content length to get it to update the disk cache
    var rand = new Random(1000);
    var contentLength = rand.Next();


    var maxAge = TimeSpan.FromTicks(DateTime.UtcNow.AddSeconds(10).Ticks);
    var meta = new ImageMetadata(DateTime.UtcNow, maxAge, contentLength);

    return await Task.FromResult(meta);
}

I keep getting the following in my debug output when refreshing after 10 seconds:
SixLabors.ImageSharp.Web.Middleware.ImageSharpMiddleware: Information: The image 'https://BLAH/BLAH.jpg?format=jpg&width=360' was not modified

With this code, I would expect the image to update every 10 seconds, but it is not. The image only gets updated when I restart the app.

I was able to get the image to update every 10 seconds by applying:

options.CacheMaxAge = TimeSpan.FromSeconds(10);

Here is my ConfigureServices

public void ConfigureServices(IServiceCollection services)
{
    services.AddImageSharp(options => {
        options.CacheMaxAge = TimeSpan.FromSeconds(10);
    })
    .ClearProviders()
    .Configure<AzureBlobStorageImageProviderOptions>(options =>
        {
            options.BlobContainers.Add(new AzureBlobContainerClientOptions
            {
                ConnectionString = "OMIT",
                ContainerName = "OMIT"
            });
        })
    .Configure<PhysicalFileSystemCacheOptions>(options =>
    {
        options.CacheFolder = "is-cache";
    })
    .SetCache(provider =>
    {
        return new PhysicalFileSystemCache(
            provider.GetRequiredService<IOptions<PhysicalFileSystemCacheOptions>>(),
            provider.GetRequiredService<IWebHostEnvironment>(),
            provider.GetRequiredService<IOptions<ImageSharpMiddlewareOptions>>(),
            provider.GetRequiredService<FormatUtilities>());
    })
    .SetCacheHash<CacheHash>()
    .AddProvider<AzureBlobStorageImageProvider>()
    .AddProvider<ProviderA>()
    .AddProvider<ProviderB>()
    .AddProcessor<ResizeWebProcessor>()
    .AddProcessor<FormatWebProcessor>()
    .AddProcessor<BackgroundColorWebProcessor>();
}

So with that said. Can I somehow apply the CacheMaxAge per provider in the ConfigureService? Or am I doing something wrong within the GetMetaDataAsync method?

Thank you!

[JimBobSquarePants]

Ok...

So yeah, you cannot currently set the cached max age per image or provider only the max age that is sent to the browser headers collection.

However, I think it's reasonable to request that the max age override affects both browser and cache values.

We could add a property to the options that chooses whether we look at the global CacheMaxAge property or the CacheControlMaxAge property of the cache metadata (which is set by the source provider) when we check to see whether the cache has expired.

Then you could set individual providers to cache images for individual times both in the browser and cache.