Handle peer 'error' events that are fired *before* the peer is emitted
in a 'peer' event. Once the peer is emitted in a 'peer' event, then
it's the consumer's responsibility to listen for errors.
This fixes the most common error in WebTorrent Desktop according to our
telemetry.
Caught this issue because of the new eviction tests. Essentially, this
change moves the socketPool into the client instance instead of a
reused variable at the module level.
When a client sends stop (or is evicted) the server will close the
websocket connection if that client is not in any other swarms (based
on peerId). However, if we are using a single socket for multiple
clients (as was the case before this commit), then other clients will
have their sockets unintentionally closed by the server.
Possibly fixes: https://github.com/feross/bittorrent-tracker/issues/196
Close websockets when peers are evicted from LRU cache, otherwise it's
possible for a peer object to be evicted from the LRU cache without the
socket being cleaned up. That will leak memory until the websocket is
closed by the remote client. It also messes up the stats.
It's not necessary to include webrtc offers because the client is not
really looking for more peers when it has just completed the torrent.
Fewer WebRTC offers = less resource usage
If the user calls:
client.stop()
client.destroy()
We should ensure that the final 'stopped' message reaches the tracker
server, even though the client will not get the response (because they
destroyed the client and no more events will be emitted).
If there are pending requests when destroy() is called, then a 1s timer
is set after which point all requests are forcibly cleaned up. If the
requests complete before the 1s timer fires, then cleanup happens right
away (so we're not stuck waiting for the 1s timer).
So, destroy() can happen one of three ways:
- immediately, if no pending requests exist
- after exactly 1s, if pending requests exist and they don't complete
within 1s
- less than 1s, if pending requests exist and they all complete before
the 1s timer fires
