Showing upload progress

[olizilla]

We want to show a progress bar to inform the user of what is happening during an upload. At a minimum we want to show how much of the data has been send to w3, e.g.

But there are some hurdles!

• The upload-client library doesn't expose an upload progress callback
• under the hood we use fetch which doesn't provide a mechanism to report upload progress.

Some options

1. Update upload-client to use XMLHttpRequest where available, which provides a progress event
2. Update upload-client to use fetch with a ReadableStream as the Request body. We wrap the body in a custom stream that just tracks number of bytes that pass through it, and use this as a proxy for bytes actually sent. This is supported in by about 60% of current browsers, notably Chrome & Edge, but not Firefox or Safari. There are caveats too, e.g. http2 connection required, outlined here

Part of #134

[olizilla]

aws suggest using xhr to show upload progress in browsers – https://github.com/aws/aws-sdk-js-v3/blob/main/packages/xhr-http-handler/README.md

fetch with a ReadableStream body requires duplex: half to be set – bluesky-social/atproto#470

[heyjay44]

This will be put on hold. Interim solution can be found in this ticket: storacha/w3up#655