Dynamic total value

[mozillazg]

First of all, many thanks for your work! I have a question: How can I dynamic setting the total value of bar?

Thanks!

[vbauerster]

You're welcome! You can't, because this feature isn't implemented. Why would you need this? What is your use case?

[mozillazg]

For example:

Download a directory with a progress, but I don't know the total size of all files in this directory(because the api for getting all files info for a directory has pagination).

[vbauerster]

If you don't know the total beforehand, you can set it to zero or negative. In that case progress bar will be replaced by simple spinner. Is it ok for you?

[mozillazg]

In that case progress bar will lose progress:

Bar#0: 0 % [|] -5s

If it could still have a progress will be better:

Bar#0: 13 % [===>----------------------------] 3s

[vbauerster]

I'm quite busy for the next two weeks, so your PR is welcome. However setting (incrementing) total dynamically, may cause undesired/unexpected behaviour of a progress bar. For example, imagine current progress shows 99%, and at that point you increment the total. It means progress will drop from 99% to something lower say 50%. But what if someone will decrement total by mistake?

[vbauerster]

I'm going to close this issue out because it doesn't seem to be getting any traction. Anyone please feel free to re-open it if you want to work on this :)

[cognusion]

Looking at this issue, seems like a big missing feature. I have lots of applications that might make a guess at a total quickly, but then update it as more information becomes available (eventual consistency). e.g. counting all the files in a filesystem or S3 bucket might take hours, but during a copy operation you may have a goro finding files and passing them along to a goro copying them elsewhere. Knowing counts beforehand is actually abnormal at scale. A more practical example is a program that reads lines from stdin and acts on them - it might not know the count ahead of time, but by having separate goros reading vs. processing (thanks, channels), it could be continuously updating the total at a different pace than the processor.

A naive, and working, patch is below. It properly updates the total, and the percentage shifts, the ETA changes, etc. The progress bar, however, is replaced by a spinner, and I'm unsure how to get that back.

func (b *Bar) SetTotal(newTotal int64) {
    b.ops <- func(s *state) {
        if s.completed == true {
            s.completed = false
        }

        s.total = newTotal
    }
}

I haven't looked into the bar issue for more than a few moments.

[vbauerster]

Dynamic total implemented. See SetTotal.

[cognusion]

Works as expected. With the while-running configurability of mpb, this is really a compelling package for tools that may run non-trivially long, and want to report feedback symbolically. Thanks for reassessing this.

[vbauerster]

You're welcome. Also if you have a chance to make animated gif with dynamic total in action, I will be happy to put it in readme.

[cognusion]

Attached please find a demo of the settotal in use. First guess is "50" then it paddles up to the actual total of 142.