Seed ratio ambiguous for partly downloaded torrents

[kovalev]

Currently, torrent seed ratio is calculated from the amount of data sent and received over a network. This method is pretty straightforward and works perfectly in almost all down/up cases. However, under some special circumstances it can lead to ambiguous situations.

First of all, if one starts to seed a torrent which has been created locally, then its amount of data received is zero, and hence its seed ratio cannot be calculated correctly on such a way. Apparently Transmission must handle this special case correctly (actually, I have never tried it by myself). Another example I have just come across with is a partly updated multiple-file torrent. Having had most of its data locally, I just loaded an updated torrent file, selected and downloaded only an updated data, then copied an old portion to the appropriate location, re-selected all data, re-verified it and started to seed. Upon completion of verification the local data size was set to 100% and everything seemed to be fine. The seed ratio however was calculated from the size of the updated part only, which was only a small fraction of all data, and thus had quickly become pretty high - of the order of 30-40 even though the upload was way lower than the total data size. Though it might be good for the enhancement of seeder rating :-), this is probably not exactly the sort of statistics some trackers ask for...

To make seed ratio less ambiguous in such special situations, I would suggest to calculate it from either "Have" instead of "Downloaded" or from the biggest of the two. This "share ratio" would handle both updated and locally created torrents correctly as soon as local data verification is complete and "Have" value is updated.

Observed in Transmission GTK 2.22+

[livings124]

Ratio is mostly relevant for your activity. That's why we use the amount we've downloaded, as opposed to the max of have and downloaded (except when downloaded is zero, for cases where seeds are added to the app directly). This is completely intentional.