David Fifield 8f965fe37b Fix sending of leftover packets. ...

There was a logic error in the code. The nextP variable was used to
store the packet that was too big to pack into the most recent DNS
response. But nextP was not tied to any particular ClientID; instead it
would be sent to whatever client happened to be the recipient of the
next response.

The confusion didn't cause connections to fail completely; any
misdirected packets were treated as out-of-sequence garbage by KCP and
dropped. But it hurt performance a lot: I saw a download go from 300
KB/s to 50 KB/s just by connecting a second client with a different
ClientID (not even sending or receiving with the second client). The
reason is that a fraction of the packets intended for the downloading
client were instead sent to the idle client, which to the downloading
client looks like a packet drop, requiring a retransmission by the
server.

We fix it by placing the leftover packet in a per-ClientID stash, rather
than a variable shared by all ClientIDs.

2020-04-29 23:29:39 -06:00

..

main.go

Fix sending of leftover packets.

2020-04-29 23:29:39 -06:00