non-deterministic behavior: undefined property errors on console

[miguelfreitas]

• WebTorrent version: v0.91.4 - 2016-05-05
• Browser name/version (if using WebTorrent in the browser): chrome 38

sometimes webtorrent works fine, but sometimes it does not (nothing changed - just page reloading)

• torrent.numPeers is updated but torrent.downloadSpeed stays 0.
• console shows the following errors (several times):

Uncaught TypeError: Cannot read property 'peerPieces' of undefined
Uncaught TypeError: Cannot read property 'isSeeder' of undefined

[feross]

@miguelfreitas Thanks for the report. Can you share a complete stack trace? If you keep the Web Console open when you refresh the page, you might be able to get a more complete trace, which would aid in debugging. Thanks!

[miguelfreitas]

guess what, it was very common behavior but now it seems difficult to reproduce...

i can't say i didn't changed anything because now i did (on my side, still the same webtorrent.min.js). but i'm pretty sure at one point i had it working/nonworking with just a browser reload.

i'll keep trying.

[miguelfreitas]

Got it:

Uncaught TypeError: Cannot read property 'peerPieces' of undefined VM644474:1
r.recalculate VM644474:1
t._onWire VM644474:1
r.emit VM644474:3
o._onWire VM644474:1
r.onHandshake VM644474:1
(anonymous function) VM644474:1
n VM644474:3
r.emit VM644474:3
o._onHandshake VM644474:2
(anonymous function) VM644474:2
o._write VM644474:2
d VM644474:6
f VM644474:6
s.write VM644474:6
s VM644474:5
r.emit VM644474:3
i VM644474:5
o.push VM644474:5
r._onChannelMessage VM644474:8
r._setupData.t._channel.onmessage

Uncaught TypeError: Cannot read property 'isSeeder' of undefined VM644474:1
(anonymous function) VM644474:1
o._rechoke VM644474:1
(anonymous function) VM644474:1
(anonymous function)

[feross]

Aha! I think I've figured this one out!

If a peer disconnects, but the handshake they already sent hasn't been
processed by the wire yet (rare!) then onHandshake could be called
after the peer is destroyed.

At this point self.wire is null, so that will get pushed into the
self.swarm.wires array and cause this issue when wire.peerPieces is accessed.

[feross]

Released as v0.93.4.

[lock]

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