Caching method results with AOP - CacheResultInterceptor

cache-result-aop-src-cache-interceptor.cs

public class CacheResultInterceptor : IInterceptor
{
    private readonly ICacheProvider _cache;

    public CacheResultInterceptor(ICacheProvider cache)
    {
        _cache = cache;
    }

    public CacheResultAttribute GetCacheResultAttribute(IInvocation invocation)
    {
        return Attribute.GetCustomAttribute(
            invocation.MethodInvocationTarget,
            typeof(CacheResultAttribute)
        )
        as CacheResultAttribute;
    }

    public string GetInvocationSignature(IInvocation invocation)
    {
        return String.Format("{0}-{1}-{2}",
            invocation.TargetType.FullName,
            invocation.Method.Name,
            String.Join("-", invocation.Arguments.Select(a => (a ?? "").ToString()).ToArray())
        );
    }

    public void Intercept(IInvocation invocation)
    {
        var cacheAttr = GetCacheResultAttribute(invocation);

        if (cacheAttr == null)
        {
            invocation.Proceed();
            return;
        }

        string key = GetInvocationSignature(invocation);

        if (_cache.Contains(key))
        {
            invocation.ReturnValue = _cache.Get(key);
            return;
        }

        invocation.Proceed();
        var result = invocation.ReturnValue;

        if (result != null)
        {
            _cache.Put(key, result, cacheAttr.Duration);
        }
    }
}