在发布的应用程序中上传到Blob存储时出现IOException

Question

我开发了一个简单的应用程序，只需将文件从文件夹上传到Azure Blob存储，从VS运行时我运行良好，但是在发布的应用程序中，偶尔会出现此错误：

ved System.IO .__ Error.WinIOError（Int32 errorCode，字符串，可能是FullPath）ved System.IO.FileStream.Init（字符串路径，FileMode模式，FileAccess访问，Int32权限，布尔useRights，FileShare共享，Int32 bufferSize，FileOptions选项，SECURITY_ATTRIBUTES secAttrs，字符串msgPath，布尔bFromProxy，布尔useLongPath，布尔checkHost）ved System.IO.FileStream..ctor（字符串路径，FileMode模式，FileAccess访问权限）ved Microsoft.WindowsAzure.Storage.Blob.CloudBlockBlobBlob.UploadFromFile（字符串路径，FileMode模式，AccessCondition，accessCondition，BlobRequestOptions选项，OperationsContext operationContext）ved Program.MainWindow.Process（对象发送者，NotifyCollectionChangedEventArgs e）

我的上传代码如下：

private void Process(object sender, NotifyCollectionChangedEventArgs e)
{
    if (paths.Count > 0){
        var currentPath = paths.Dequeue();
        CloudStorageAccount storageAccount = CloudStorageAccount.Parse(UserSettings.Instance.getConnectionString());
        CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();
        CloudBlobContainer blobContainer = blobClient.GetContainerReference(UserSettings.Instance.getContainer());
        CloudBlockBlob b = blobContainer.GetBlockBlobReference(System.IO.Path.GetFileName(currentPath));
        try
        {
           b.UploadFromFile(currentPath, FileMode.Open);
        }
        catch (StorageException s)
        {
            throw new System.InvalidOperationException("Could not connect to the specified storage account. Please check the configuration.");
        }
        catch (IOException exc)
        {
            throw new System.InvalidOperationException(exc.StackTrace);
        }
    }
}

捕获中的IOException有时会被击中，您知道如何解决此问题吗？

如果查看文档，我会被告知，如果发生存储服务错误，则会发生异常。任何想法如何进一步调查？

https://docs.microsoft.com/zh-cn/java/api/com.microsoft.azure.storage.blob._cloud_blob.uploadfromfile?view=azure-java-legacy#com_microsoft_azure_storage_blob__cloud_blob_uploadFromFile_final_String_

Answer 1

我发现只有当我将文件复制到受监视的文件夹中时才会出现错误，如果我拖动它们，它就可以正常工作吗？

看起来您的应用程序正在尝试读取仍在写入磁盘（不完整）或被其他进程锁定的本地文件。拖动文件在某种程度上是“原子”操作（即非常快），因此大大减少了出现此错误的机会。

尝试实现此答案中的方法来测试文件在调用之前是否未锁定UploadFromFile()。现在，根据您的代码逻辑，如果文件被锁定，您将需要实现某种形式的“重试”。这是一个例子：

    protected virtual bool IsFileLocked(FileInfo file)
    {
        FileStream stream = null;

        try
        {
            stream = file.Open(FileMode.Open, FileAccess.Read, FileShare.None);
        }
        catch (IOException)
        {
            //the file is unavailable because it is:
            //still being written to
            //or being processed by another thread
            //or does not exist (has already been processed)
            return true;
        }
        finally
        {
            if (stream != null)
                stream.Close();
        }

        //file is not locked
        return false;
    }

    private void Process(object sender, NotifyCollectionChangedEventArgs e)
    {
        if (paths.Count > 0)
        {
            var currentPath = paths.Dequeue();
            CloudStorageAccount storageAccount = CloudStorageAccount.Parse(UserSettings.Instance.getConnectionString());
            CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();
            CloudBlobContainer blobContainer = blobClient.GetContainerReference(UserSettings.Instance.getContainer());
            CloudBlockBlob b = blobContainer.GetBlockBlobReference(System.IO.Path.GetFileName(currentPath));
            try
            {
                FileInfo fi = new FileInfo(currentPath);
                while (IsFileLocked(fi))
                    Thread.Sleep(5000); // Wait 5 seconds before checking again
                b.UploadFromFile(currentPath, FileMode.Open);
            }
            catch (StorageException s)
            {
                throw new System.InvalidOperationException("Could not connect to the specified storage account. Please check the configuration.");
            }
            catch (IOException exc)
            {
                throw new System.InvalidOperationException(exc.StackTrace);
            }
        }
    }

请注意，这决不能保证文件不会在IsFileLocked()调用和b.UploadFromFile()调用之间被另一个进程再次锁定。