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Upload sample with pause/resume

See original GitHub issue

We’re trying to upload a large file and want to support pause/resume. However the upload doesn’t finish and is stuck in the while loop:

TransferManager.Configurations.BlockSize = 4 * 1024 * 1024; // 4 MB

// create stream with 100 MB
var content = Enumerable
    .Range(0, 100 * 1024 * 1024)
    .Select(i => (byte)'b')
var source = new MemoryStream(content);

TransferCheckpoint checkPoint = null;
while (true)
    // Resume if there is already a checkpoint
    var context = checkPoint != null
        ? new SingleTransferContext(checkPoint)
        : new SingleTransferContext();

    context.ShouldOverwriteCallback = (src, dest) => true;
    context.LogLevel = Microsoft.WindowsAzure.Storage.LogLevel.Verbose;
    var recorder = new ProgressRecorder();
    context.ProgressHandler = recorder;
        // Interrupt upload after 20 seconds
        using (var cts = new CancellationTokenSource(TimeSpan.FromSeconds(20)))
            await TransferManager.UploadAsync(source, blob, null, context, cts.Token);
        // break if no exception occured, i.e. the upload finished
    catch (OperationCanceledException) { }
    checkPoint = context.LastCheckpoint; // save the last checkpoint

What are we doing wrong?

Issue Analytics

  • State:closed
  • Created 7 years ago
  • Reactions:1
  • Comments:15 (5 by maintainers)

github_iconTop GitHub Comments

dgodwin1175commented, Nov 21, 2017

Once the upload is cancelled, you can save the checkpoint like this:

            return TransferManager.UploadAsync(file.FileName, destinationBlob, options, context, token);
        catch (TaskCanceledException ex)
            checkpoint = context.LastCheckpoint;
            memoryStream = new MemoryStream();
            formatter.Serialize(memoryStream, checkpoint);
            file.Checkpoint = Convert.ToBase64String(memoryStream.ToArray());
            throw ex;

And to resume your upload from the saved checkpoint:

        memoryStream = new MemoryStream(Convert.FromBase64String(file.Checkpoint));
        checkpoint = formatter.Deserialize(memoryStream) as TransferCheckpoint;
        var context = new SingleTransferContext(checkpoint);
        context.SetAttributesCallback = (destination) =>
            var destBlob = destination as CloudBlob;
            destBlob.Properties.ContentType = ContentType;

Then upload the file again with the above context object.

haldarsumanacommented, Sep 23, 2021

Is there a way to save context.LastCheckpoint in the database or as a file to use it later to start blob upload from the last checkpoint by using Azure Data Movement library?

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