Force cache to refresh?

vkhazen · July 29, 2021, 4:20pm

Hi service stack team and users. we use the [CacheResponse(Duration = 72000, MaxAge = 30)] tag to cache response. I want to have a background job that runs in intervals much smaller than 72000 seconds so that user will always hit the cache because our endpoint is slow if it hits a cache miss. Is there a way to accomplish this? Thanks

Update:
We have been considering custom caching but wondering if we can accomplish the same thing using bulit-in CacheResponse feature

mythz · July 29, 2021, 8:46pm

If you want to access the Service at a lower cache duration than what you’ve specified for the Service I would recommend that you maintain different Services, where your Cached API uses the gateway to invoke an internal non-cached services as done in our https://northwind.netcore.io example, e.g:

github.com

NetCoreApps/Northwind/blob/master/src/Northwind.ServiceInterface/CachedServices.cs

using Northwind.ServiceModel;
using ServiceStack;

namespace Northwind.ServiceInterface
{
    [CacheResponse(Duration = 60 * 60, MaxAge = 30 * 60)]
    public class CachedServices : Service
    {
        public object Get(CachedGetAllCustomers request) => 
            Gateway.Send(new GetAllCustomers());

        public object Get(CachedGetCustomerDetails request) => 
            Gateway.Send(new GetCustomerDetails { Id = request.Id });

        public object Get(CachedGetOrders request) => 
            Gateway.Send(new GetOrders { CustomerId = request.CustomerId, Page = request.Page });
    }
}

You can use AutoMapping’s ConvertTo API to convert an entire Request DTO into a different type, e.g:

[CacheResponse(Duration = 72000, MaxAge = 30)]
public class CachedServices : Service
{
    public object Get(CachedMyRequest request) => 
        Gateway.Send(request.ConvertTo<MyRequest>());
}

vkhazen · July 29, 2021, 9:40pm

Thanks for the response.
But I don’t think we are on the same page.

I don’t want to call a cached API at a smaller interval.
I want to ask all my users to call GET CachedMyRequest instead of some API that does exactly the same thing but with smaller cache expiration value

[CacheResponse(Duration = 72000, MaxAge = 30)]
public class CachedServices : Service
{
    public object Get(CachedMyRequest request) => 
        Gateway.Send(request.ConvertTo<MyRequest>());
}

but since GET CachedMyRequest is slow, I want the users to always hit the cache.

In order to do that, I want to have a background job that keeps updating the cache every 3600 seconds (e.g. res:/cachedmyrequest.json, res:/cachedmyrequest.json.deflate, res:/cachedmyrequest.html, res:/cachedmyrequest.html.deflate) so that before the cache items expire, the cache values were already updated with newer values and the cache item TTL were already reset to 72000

mythz · July 30, 2021, 2:49am

Doesn’t sound like you’ll be able to handle your use-case with [CacheResponse] which uses the classic Lazy Loading caching pattern and a dynamic cache key based on the end user request.

If you want to prepopulate the cache you’re going to need a constant and deterministic cache key that you control yourself that your background job populates and your Service implementations returns.