ServiceStack.HttpCacheFeature.HandleCacheResponses C# (CSharp) Method

        public void HandleCacheResponses(IRequest req, IResponse res, object response)
        {
            if (req.IsInProcessRequest())
                return;

            if (response is Exception || res.StatusCode >= 300)
                return;

            var cacheInfo = req.GetItem(Keywords.CacheInfo) as CacheInfo;
            if (cacheInfo != null && cacheInfo.CacheKey != null)
            {
                if (CacheAndWriteResponse(cacheInfo, req, res, response))
                    return;
            }

            var httpResult = response as HttpResult;
            if (httpResult == null)
                return;

            cacheInfo = httpResult.ToCacheInfo();

            if ((req.Verb != HttpMethods.Get && req.Verb != HttpMethods.Head) ||
                (httpResult.StatusCode != HttpStatusCode.OK && httpResult.StatusCode != HttpStatusCode.NotModified))
                return;

            if (httpResult.LastModified != null)
                httpResult.Headers[HttpHeaders.LastModified] = httpResult.LastModified.Value.ToUniversalTime().ToString("r");

            if (httpResult.ETag != null)
                httpResult.Headers[HttpHeaders.ETag] = httpResult.ETag.Quoted();

            if (httpResult.Expires != null)
                httpResult.Headers[HttpHeaders.Expires] = httpResult.Expires.Value.ToUniversalTime().ToString("r");

            if (httpResult.Age != null)
                httpResult.Headers[HttpHeaders.Age] = httpResult.Age.Value.TotalSeconds.ToString(CultureInfo.InvariantCulture);

            var alreadySpecifiedCacheControl = httpResult.Headers.ContainsKey(HttpHeaders.CacheControl);
            if (!alreadySpecifiedCacheControl)
            {
                var cacheControl = BuildCacheControlHeader(cacheInfo);
                if (cacheControl != null)
                    httpResult.Headers[HttpHeaders.CacheControl] = cacheControl;
            }

            if (req.ETagMatch(httpResult.ETag) || req.NotModifiedSince(httpResult.LastModified))
            {
                res.EndNotModified();
            }
        }