public class SizeLimitedFileBitmapTileCache : FileBitmapTileCache
    {
        private long totalSize;
        public SizeLimitedFileBitmapTileCache(string cacheDirectory, string cacheId)
            : base(cacheDirectory, cacheId)
        {
            LimitedSize = 100000000;
        }

        public double LimitedSize { get; set; }

        protected override void SaveTileCore(ThinkGeo.MapSuite.Core.Tile tile)
        {
            base.SaveTileCore(tile);
            TileMatrixCell cell = TileMatrix.GetCell(tile.BoundingBox.GetCenterPoint());
            if (cell != null)
            {
                string fileCacheName = GetTileImageFileName(cell.Row, cell.Column, tile.Scale);
                if (File.Exists(fileCacheName))
                {
                    totalSize += new FileInfo(fileCacheName).Length;
                    if (totalSize > LimitedSize)
                    { 
                        // Do you logic here.
                    }
                }
            }
        }

        private string GetTileImageFileName(long row, long column, double scale)
        {
            string tileImageFileName = CacheDirectory;

            if (!tileImageFileName.EndsWith(@"\", StringComparison.OrdinalIgnoreCase))
            {
                tileImageFileName += @"\";
            }

            //Append cacheId
            if (!string.IsNullOrEmpty(CacheId))
            {
                tileImageFileName += CacheId + @"\";
            }

            bool foundAproximiateScaleDirectory = false;

            if (Directory.Exists(CacheDirectory + "\\" + CacheId))
            {
                string[] targetDirectories = Directory.GetDirectories(CacheDirectory + "\\" + CacheId, "*.*", SearchOption.TopDirectoryOnly);
                foreach (string targetDirectory in targetDirectories)
                {
                    DirectoryInfo directoryInfo = new DirectoryInfo(targetDirectory);
                    string scaleFolder = directoryInfo.Name;
                    double targetDirectoryScale = Convert.ToDouble(scaleFolder, CultureInfo.InvariantCulture);

                    if (Math.Abs(scale - targetDirectoryScale) < 1e-4)
                    {
                        tileImageFileName = targetDirectory + @"\";
                        foundAproximiateScaleDirectory = true;
                        break;
                    }
                }
            }

            if (!foundAproximiateScaleDirectory)
            {
                tileImageFileName += scale.ToString(CultureInfo.InvariantCulture) + @"\";
            }

            //Append row
            tileImageFileName += row.ToString(CultureInfo.InvariantCulture) + @"\";

            //Append column
            tileImageFileName += column.ToString(CultureInfo.InvariantCulture);

            //Append extension
            string extension = ImageFormat.ToString().ToLowerInvariant();
            tileImageFileName += "." + extension;

            return tileImageFileName;
        }
    }