/// <summary>
        /// 写入文件,可不等待
        /// </summary>
        /// <param name="fileStartPoint">从文件的哪里开始写</param>
        /// <param name="data">写入的数据</param>
        /// <param name="dataOffset"></param>
        /// <param name="dataLength"></param>
        public async Task WriteAsync(long fileStartPoint, byte[] data, int dataOffset, int dataLength)
        {
            var task = new TaskCompletionSource <bool>();

            var fileSegment = new FileSegment(fileStartPoint, data, dataOffset, dataLength, task);

            FileSegmentList.Enqueue(fileSegment);
            await task.Task;
        }
        /// <summary>
        /// 加入写文件队列
        /// </summary>
        public void QueueWrite(long fileStartPoint, byte[] data, int dataOffset, int dataLength)
        {
            var fileSegment = new FileSegment(fileStartPoint, data, dataOffset, dataLength);

            FileSegmentList.Enqueue(fileSegment);
        }