progress should be based on 100% scale

[pombredanne]

reported by @chinyeungli

Scanning files...
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I thought the above is the progress bar based on percentage. But then I realize it's number of file counts.

I think 100% scale make more scenes as not many users care about how many files have been processed, but how much left to be completed.

[pombredanne]

To compute a percentage we need to know ahead of time the number of items that will be computed.

This means walking the file system first to count files and weight that possibly based on the size of each file.

This is not a big deal, but would possibly slow down a bit every scan. Another thing could be to make the progress being displayed based on an option rather than by default (for instance rsync displays progress on demand only).

[pombredanne]

I am closing as wontfix because it is either never possible to exactly know a correct percentage or getting a reasonable percentage is likely prohibitively expensive as this requires a whole pre-processing of a scanned tree.

Please reopen if you feel strongly about this.