public MemoryMapper(string filePath, long initialFileSize)
        {
            try
            {
                if (initialFileSize <= 0 || initialFileSize % Constants.AllocationGranularity != 0)
                {
                    throw new ArgumentException("The initial file size must be a multiple of 64Kb and grater than zero");
                }

                bool existingFile = File.Exists(filePath);
                fs = new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None);
                if (existingFile)
                {
                    if (fs.Length <= 0 || fs.Length % Constants.AllocationGranularity != 0)
                    {
                        throw new ArgumentException("Invalid file. Its lenght must be a multiple of 64Kb and greater than zero");
                    }
                }
                else
                {
                    fs.SetLength(initialFileSize);
                }
                mapping = MemoryMapping.Create(fs);
            }
            catch
            {
                Dispose();
                throw;
            }
        }
        public DataFile(string filePath, long initialSize, int growthIncrement)
        {
            try
            {
                bool isNew = !File.Exists(filePath);
                memoryMapper          = new MemoryMapper(filePath, initialSize);
                mapping               = MemoryMapping.Create(memoryMapper.fs, Constants.AllocationGranularity);
                dataFileHeaderPointer = (DataFileHeader *)mapping.GetBaseAddress();
                this.growthIncrement  = (growthIncrement + Constants.AllocationGranularityMask) / Constants.AllocationGranularity * Constants.AllocationGranularity;

                if (isNew)
                {
                    InitializeHeader();
                }
                else
                {
                    ValidateHeader();
                }
            }
            catch
            {
                Dispose();
                throw;
            }
        }