Immediate.Cache

Immediate.Cache is a collection of classes that simplify caching responses from Immediate.Handlers handlers.

Installing Immediate.Cache

You can install Immediate.Cache with NuGet:

Install-Package Immediate.Cache

Or via the .NET Core command line interface:

dotnet add package Immediate.Cache

Either commands, from Package Manager Console or .NET Core CLI, will download and install Immediate.Cache.

Using Immediate.Cache

Creating a Cache

Create a subclass of ApplicationCacheBase, which will serve as the cache for a particular handler. An example:

[Handler]
public static partial class GetValue
{
	public sealed record Query(int Value);
	public sealed record Response(int Value);

	private static ValueTask<Response> HandleAsync(
		Query query,
		CancellationToken _
	) => ValueTask.FromResult(new Response(query.Value));
}

public sealed class GetValueCache(
	IMemoryCache memoryCache,
	Owned<IHandler<GetValue.Query, GetValue.Response>> ownedHandler
) : ApplicationCacheBase<GetValue.Query, GetValue.Response>(
	memoryCache,
	ownedHandler
)
{
	protected override string TransformKey(GetValue.Query request) =>
		$"GetValue(query: {request.Value})";
}

In this case, the GetValueCache class will serve as a cache for the GetValue IH handler.

Register the Cache with DI

In your Program.cs file:

• Ensure that Memory Cache is registered, by calling:

services.AddMemoryCache();

• Register Owned<> as a singleton

services.AddSingleton(typeof(Owned<>));

• Register your cache service(s) as a singleton(s)

services.AddSingleton<GetValueCache>();

Retrieve Data From the Cache

Using an instance of the GetValueCache class that you have created above, you can simply call:

var response = await cache.GetValue(request, token);

If there is a cached value, it will be returned; otherwise a temporary scope will be used to create the handler and execute it; and the returned value will be stored.

Note

If simultaneous requests are made while the handler is executing, they will wait for the first handler to complete, rather than executing the handler a second/simultaenous time.

Removing Data From the Cache

Using an instance of the GetValueCache class that you have created above, you can remove cached data by calling:

await cache.RemoveValue(request);

Note

If a handler is running based on this request, it will be cancelled, and any callers waiting on the results from this handler will experience a CancellationToken cancellation.

Updating Data In the Cache

Using an instance of the GetValueCache class that you have created above, you can assign cached data by calling:

await cache.SetValue(request, response);

Note

If a handler is running based on this request, it will be cancelled, and any callers waiting on the results from this handler will immediately receive the updated response.