Fix 'left' parameter on seed

[alxhotel]

Fixes #1105

As mentioned by @feross, this PR just verifies the torrent before trying to discover peers.

I have tested it by seeding and downloading and it works fine.

If anyone has better solutions, let me know.

[feross]

Thanks for taking a stab at solving this!

This doesn't seem to fix the issue for me. Piece verification is asynchronous so it is not guaranteed to complete before the Discovery object is initialized and sends messages to the tracker servers.

I used webtorrent-cli pointing to a version of webtorrent with this PR on it and got this:

DEBUG='bittorrent-tracker*' ./bin/cmd.js seed ~/Desktop/blah.png
  bittorrent-tracker:client new client c97eedde957e0689871a450f537c2cf19af36276 +0ms
  bittorrent-tracker:udp-tracker new udp tracker udp://explodie.org:6969 +0ms
  bittorrent-tracker:udp-tracker new udp tracker udp://tracker.coppersurfer.tk:6969 +0ms
  bittorrent-tracker:udp-tracker new udp tracker udp://tracker.empire-js.us:1337 +0ms
  bittorrent-tracker:udp-tracker new udp tracker udp://tracker.leechers-paradise.org:6969 +0ms
  bittorrent-tracker:udp-tracker new udp tracker udp://tracker.opentrackr.org:1337 +0ms
  bittorrent-tracker:client setInterval 900000 +2ms
  bittorrent-tracker:client send `start` { numwant: 50, uploaded: 0, downloaded: 0, left: 119515, event: 'started' } +1ms

Note that left is not 0. I think we would need to wait for the verification to actually complete.

[alxhotel]

Ah yeah, of course. Thanks for the feedback!

I've made some changes to take the asynchronous behaviour into account. (Still don't know if it's the best approach)

I also had to change the tests blocklist-dht and blocklist-tracker because the clients were sharing the download path. This meant that client2 always had the file downloaded, so it wasn't blocking any peers because it didn't need to. By separating the download paths, now the behaviour is as expected. (It was working previously because the discovery was always trigerring before verifying the pieces)

[feross]

the clients were sharing the download path

Thanks for catching this!

[feross]

This is a perfect PR. Thank you @alxhotel ❤️

[feross]

0.107.4