ServiceStack MemoryCacheClient not Caching

Question

I am a relative noob when it comes to ServiceStack and have inherited a project which appears to be trying to make use of the MemoryCacheClient but it seems that no caching appears to take place beyond the scope of a single request e.g. the cache is not persisted between requests, regardless of what expiry I add.

Is that expected? Here is the ICacheManager implementation:

public class CacheManager : ICacheManager
{
    public CacheManager(ICacheClient cacheClient)
    {
        CacheClient = cacheClient;
    }

    public void Clear(IEnumerable<string> cacheKeys)
    {
        Clear(cacheKeys.ToArray());
    }

    public void Clear(params string[] cacheKeys)
    {
        CacheClient.ClearCaches(cacheKeys.ToArray());
    }

    public ICacheClient CacheClient { get; private set; }

    public T Resolve<T>(string cacheKey, Func<T> createCacheFn) where T : class
    {
        return Resolve(cacheKey, new TimeSpan(0, 15, 0), createCacheFn);
    }

    public T Resolve<T>(string cacheKey, TimeSpan expireIn, Func<T> createCacheFn) where T : class
    {
      var cacheResult = CacheClient.Get<T>(cacheKey);
      if (cacheResult != null)
        return cacheResult;

        var item = createCacheFn();
        CacheClient.Set(cacheKey, item, expireIn);
        return item;
    }
}

This is wired up using the AutoFac ContainerBuilder as follows:

_builder.Register(c => new MemoryCacheClient())
    .As<ServiceStack.CacheAccess.ICacheClient>();

_builder.RegisterType<CacheManager>()
    .As<ServiceStack.CacheAccess.ICacheManager>();

Answer 1

The MemoryCacheClient instance have to be unique. So you have to tell Autofac to create only a single instance :

_builder.Register(c => new MemoryCacheClient())
        .As<ServiceStack.CacheAccess.ICacheClient>()
        .SingleInstance();

When you don't specify the instance scope mode, Autofac uses instancePerDependency : a new instance will be returned each time you resolve it. See instance scope documentation for more information about instance scope.