Downloading Files that are Unchecked

[smmalis]

I started downloading a torrent that included several files. The properties box came up, and I unchecked all but one file (the one I wanted). I was later startled to see that I was downloading one of the files I had unchecked. After I checked and unchecked it again, the download stopped. Screenshot attached.

[smmalis]

Screenshot of the bug in action.

[livings124]

The bittorrent protocol requires data to be downloaded in blocks, and data cannot be finished downloading until the full blocks of a selected file are received. It seems that this 2 mb is the rest of the final block for the selected file, so it must be downloaded in order to seed.

[smmalis]

I'm pretty sure that this is a bug in Transmission though. After I rechecked and re-unchecked the second file it stopped and hasn't resumed. I tried dl'ing the same torrent in uTorrent and this didn't happen. It seems to be in how Transmission handles folders. The second folder was unchecked, so it wasn't downloaded. I think that if I had unchecked the first folder and then rechecked the one file, I would have been fine. More info: the third file in the first folder was also downloaded, despite being unchecked as well.

[charles]

What is the piece size of that torrent?

[charles]

Please reopen this ticket with the piece size from the "Information" tab in the Details dialog

[smmalis]

The piece size is set to 2.0 MB, but remember: the first file is dl'ed to 100, the second file is currently at 85, and the third file is at 100. The last two were not checked at the beginning, and I checked and unchecked the second file which caused it to stop.

[livings124]

When you checked the second file, it started asking for its data. That overlaps with the third file, which is why you got data for that. The second file is 2mb, so part of that most definitely laps onto the first file.

If you can replicate this with another torrent file with files that aren't as small/smaller than the piece size, reopen. Right now it definitely looks like the issue I first described.

[smmalis]

Except that I unchecked the second file. Why would the third file still download?

[livings124]

If the data was already asked for and being sent. It's a 121 byte file; it's not unreasonable to think it came near instantaneously.

Again, if this can be replicated with files of size larger than the piece size, reopen this.

[charles]

The third file was in a piece that overlaps with the second file, and was most likely requested before you unchecked the second file.

There really are valid reasons for downloading entire pieces whether you want all the data in the piece or not. However, you could argue that it makes more sense to `hide' the excess data so that it's not confusing or annoying to users. There's already a ticket open for this, #532... maybe this ticket should be folded into that one.