SqlDataReader 在读取大行时不遵守取消请求

如何解决SqlDataReader 在读取大行时不遵守取消请求

请考虑此代码示例：

        const int timeoutInSeconds = 60; // 1 minute
        static readonly CancellationTokenSource tokenSource = new CancellationTokenSource();

        public static void Main()
        {
            try
            {
                tokenSource.CancelAfter(timeoutInSeconds * 1000);

                Task.WaitAll(ReadLargeFile(),TimeStat());
            }
            catch (AggregateException ex)
            {
                foreach (var e in ex.InnerExceptions)
                {
                    Console.WriteLine(e.Message);
                }
            }
            finally
            {
                tokenSource.dispose();
            }
        }

        static async Task ReadLargeFile()
        {
            using (var con = new sqlConnection($"some connection string"))
            {
                await con.OpenAsync(tokenSource.Token).ConfigureAwait(false);

                using (var command = new sqlCommand("SELECT * FROM dbo.TableWithFatRows where Id = 1",con))
                {
                    command.CommandTimeout = timeoutInSeconds;

                    sqlDataReader reader = await command.ExecuteReaderAsync(CommandBehavior.Default,tokenSource.Token).ConfigureAwait(false);

                    while (await reader.ReadAsync(tokenSource.Token).ConfigureAwait(false)) // we expect cancellation here
                    {
                        Console.WriteLine($"Finished Read iteration. Checking cancellation ");

                        tokenSource.Token.ThrowIfCancellationRequested(); // but actually we got it here

                        // some work
                    }
                }
            }
        }

        static async Task TimeStat(int secondsDelay = 10)
        {
            try
            {
                while (!tokenSource.IsCancellationRequested)
                {
                    Console.WriteLine($"#TotalSeconds: {stopwatch.Elapsed.TotalSeconds}");

                    await Task.Delay(new TimeSpan(0,secondsDelay),tokenSource.Token).ConfigureAwait(false); ;
                }
            }
            catch (TaskCanceledException)
            {
                Console.WriteLine("Cancellation has been requested. Finishing TimeStat task.");
            }
        }

问题 - 我们必须从表中查询非常大的行。例如。每个 15Mb。 而且通常读取一行需要10分钟以上。

问题是 - 如何强制 sqlDataReader 中止/关闭数据检索过程？

目前在上面的代码中 - sqlDataReader 只是忽略请求的取消，可能是设计使然。 因此，执行会卡在数据读取过程 (await reader.ReadAsync(tokenSource.Token)) 上，直到大行完全下载并违反所有连接/命令/取消令牌超时。