c# - 文件上传到 Web API 和 Azure 抛出 HttpException

Question

有时，当中国用户将小文件 (100-200kB) 上传到将文件直接传递到 Azure blob 的 WebAPI 服务时，我会遇到此异常:

System.Web.HttpException: The client is disconnected because the underlying request has been completed. There is no longer an HttpContext available.

Controller 代码如下所示:

[HttpPost]
public async Task<IHttpActionResult> Upload()
{
    var stream = await Request.Content.ReadAsStreamAsync();

    var guid = Guid.NewGuid().ToString();
    var blob = /*CloudBlobContainer*/.GetBlockBlobReference(guid);

    blob.Properties.ContentType = Request.Content.Headers.ContentType.MediaType;
    blob.UploadFromStream(stream);

    return Ok(guid);
}

以及堆栈跟踪:

System.Web.HttpException: The client is disconnected because the underlying request has been completed.  There is no longer an HttpContext available.

at System.Web.HttpBufferlessInputStream.Read(Byte[] buffer, Int32 offset, Int32 count)

at System.Web.Http.WebHost.SeekableBufferedRequestStream.Read(Byte[] buffer, Int32 offset, Int32 count)

at Microsoft.WindowsAzure.Storage.Core.Util.StreamExtensions.WriteToSync[T](Stream stream, Stream toStream, Nullable`1 copyLength, Nullable`1 maxLength, Boolean calculateMd5, Boolean syncRead, ExecutionState`1 executionState, StreamDescriptor streamCopyState)

at Microsoft.WindowsAzure.Storage.Blob.CloudBlockBlob.UploadFromStreamHelper(Stream source, Nullable`1 length, AccessCondition accessCondition, BlobRequestOptions options, OperationContext operationContext)

at .Controllers.FileController.<Upload>d__5.MoveNext()

可以安全地假设这只是互联网连接不良吗？在这种情况下，我可以捕捉并忽略它。客户端有一个安全的重试机制，以防上传出错。

或者我的代码有问题吗？

Answer 1

代码对我来说看起来不错，在这种情况下重试是有意义的。

您可能还想为您的存储帐户启用存储分析，这样如果下次您遇到此异常，您将能够通过检查日志来判断请求是否已到达 Azure 存储服务器端，请参阅有关详细信息，请参阅下面帖子中的“端到端跟踪”部分。

http://azure.microsoft.com/en-us/documentation/articles/storage-monitoring-diagnosing-troubleshooting/