Allow promotion of the "from" value in peer_atom (and still show where it was first discovered)

[Longinus00]

Transmission uses the "from" value in peer_atom when determining atoms it wants to keep or connect to. Currently the "from" value is set in stone when transmission first learns of a peer even if it finds it through "better" sources later.

[charles]

Longinus00, I don't think this patch does any harm, but I'm not sure that I see the benefit either. What does this win compared to promoting an atom's "from" field from a worse state to a higher one?

[livings124]

It would put all peers into a fair state when picking the best based on where it's from. Since you're using the criteria of where it's from, best to use the best (or worst) place it was discovered, instead of which happened to be the first.

[charles]

livings124, wouldn't promotion do the same thing?

[livings124]

Assuming none of the code uses the information, then ya, it would be the same. Is multiple "froms" something we should show in the GUI?

[Longinus00]

My reasoning for not simply replacing the 'from' value was two fold:

1. give a slight preference to peers which are more 'visible'
2. keep better records of where peers are from

The reason I made my patch compatible with the old "from" is because it's used in the mac client. The only other place I saw it being used was in transmission-remote-cli but that project doesn't provide much backward compatibility so changing things up there probably isn't an issue.

[livings124]

The Mac client can always be changed if needed.

[charles]

Longinus00, if you're happy with this patch go ahead & commit

[livings124]

r11578