System.Net.Cache.FtpRequestCacheValidator.ValidateFreshness C# (CSharp) Method

        protected internal override CacheFreshnessStatus ValidateFreshness()
        {

            if (HttpProxyMode)
            {
                if (CacheStream != Stream.Null)
                {
                    if(Logging.On)Logging.PrintInfo(Logging.RequestCache, SR.GetString(SR.net_log_cache_replacing_entry_with_HTTP_200));

                    // HTTP validator cannot parse FTP status code and other metadata
                    if (CacheEntry.EntryMetadata == null)
                        CacheEntry.EntryMetadata = new StringCollection();

                    CacheEntry.EntryMetadata.Clear();
                    CacheEntry.EntryMetadata.Add("HTTP/1.1 200 OK");
                }
                return base.ValidateFreshness();
            }

            DateTime nowDate = DateTime.UtcNow;

            if(Logging.On)Logging.PrintInfo(Logging.RequestCache, SR.GetString(SR.net_log_cache_now_time, nowDate.ToString("r", CultureInfo.InvariantCulture)));

            // If absolute Expires can be recovered
            if (CacheEntry.ExpiresUtc != DateTime.MinValue)
            {
                //Take absolute Expires value
                if(Logging.On)Logging.PrintWarning(Logging.RequestCache, SR.GetString(SR.net_log_cache_max_age_absolute, CacheEntry.ExpiresUtc.ToString("r", CultureInfo.InvariantCulture)));
                if (CacheEntry.ExpiresUtc < nowDate) {
                    return CacheFreshnessStatus.Stale;
                }
                return CacheFreshnessStatus.Fresh;
            }

            TimeSpan age  = TimeSpan.MaxValue;

            if(CacheEntry.LastSynchronizedUtc != DateTime.MinValue)
            {
                age = nowDate - CacheEntry.LastSynchronizedUtc;
                if(Logging.On)Logging.PrintInfo(Logging.RequestCache, SR.GetString(SR.net_log_cache_age1, ((int)age.TotalSeconds).ToString(NumberFormatInfo.InvariantInfo), CacheEntry.LastSynchronizedUtc.ToString("r", CultureInfo.InvariantCulture)));
            }

            //
            // Heruistic expiration
            //
            if (CacheEntry.LastModifiedUtc != DateTime.MinValue)
            {
                TimeSpan span = (nowDate - CacheEntry.LastModifiedUtc);
                int maxAgeSeconds = (int)(span.TotalSeconds/10);
                if(Logging.On)Logging.PrintInfo(Logging.RequestCache, SR.GetString(SR.net_log_cache_no_max_age_use_10_percent, maxAgeSeconds.ToString(NumberFormatInfo.InvariantInfo), CacheEntry.LastModifiedUtc.ToString("r", CultureInfo.InvariantCulture)));
                if (age.TotalSeconds < maxAgeSeconds) {
                    return CacheFreshnessStatus.Fresh;
                }
                return CacheFreshnessStatus.Stale;
            }

            // Else we can only rely on UnspecifiedMaxAge hint
            if(Logging.On)Logging.PrintWarning(Logging.RequestCache, SR.GetString(SR.net_log_cache_no_max_age_use_default, ((int)(UnspecifiedMaxAge.TotalSeconds)).ToString(NumberFormatInfo.InvariantInfo)));
            if (UnspecifiedMaxAge >= age)
            {
                return CacheFreshnessStatus.Fresh;
            }

            return CacheFreshnessStatus.Stale;
            //return OnValidateFreshness(this);
        }