Deduplicate trackers, fixes #4

[valpackett]

I'm not actually sure whether we need to sum up the DownloadCount or just ignore the duplicates…

[metalmatze]

So this fix is just about the download count, which was previously the sum of all trackers?

[valpackett]

It's about duplicate entries in TrackerStats, by using a hash map the entries are deduplicated and the #4 error is prevented

[metalmatze]

Alright, I can recreate the issue on my machine now, thanks for the help.

I have a lot of counters that are -1. I think we should update the PR to set those to 0.

transmission_torrent_downloads_total{id="2",name="pwned-passwords-2.0.txt.7z",tracker="udp://tracker.zer0day.to:1337"} -1
transmission_torrent_downloads_total{id="2",name="pwned-passwords-2.0.txt.7z",tracker="udp://tracker1.wasabii.com.tw:6969"} -1
...
transmission_torrent_leechers{id="2",name="pwned-passwords-2.0.txt.7z",tracker="udp://tracker.zer0day.to:1337"} -1
transmission_torrent_leechers{id="2",name="pwned-passwords-2.0.txt.7z",tracker="udp://tracker1.wasabii.com.tw:6969"} -1
...
transmission_torrent_seeders{id="2",name="pwned-passwords-2.0.txt.7z",tracker="udp://tracker.zer0day.to:1337"} -1
transmission_torrent_seeders{id="2",name="pwned-passwords-2.0.txt.7z",tracker="udp://tracker1.wasabii.com.tw:6969"} -1

Otherwise this looks good to me.

[jonnrb]

I didn’t notice this until now, but I think the dups are due to udp and http trackers with the same fqdn in one torrent. Should those be treated as the same tracker in the stats? Might it be a good future improvement to add a label for the protocol used?

[metalmatze]

I'll merge this and then do some more testing with it. Thanks and sorry for the huge delay!