73280595a8 for #2751 added a "clientSet" interface to
distinguish the two cases of a client being singly connected (the
common case) vs tolerating multiple connections from the client at
once. At the time (three years ago) it was kinda an experiment
and we didn't know whether it'd stop the reconnect floods we saw
from certain clients. It did.
So this promotes it to a be first-class thing a bit, removing the
interface. The old tests from 73280595a were invaluable in ensuring
correctness while writing this change (they failed a bunch).
But the real motivation for this change is that it'll permit a future
optimization to add flow tracking for stats & performance where we
don't contend on Server.mu for each packet sent via DERP. Instead,
each client can track its active flows and hold on to a *clientSet and
ask the clientSet per packet what the active client is via one atomic
load rather than a mutex. And if the atomic load returns nil, we'll
know we need to ask the server to see if they died and reconnected and
got a new clientSet. But that's all coming later.
Updates #3560
Change-Id: I9ccda3e5381226563b5ec171ceeacf5c210e1faf
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This repository contains the majority of Tailscale's open source code.
Notably, it includes the tailscaled daemon and
the tailscale CLI tool. The tailscaled daemon runs on Linux, Windows,
macOS, and to varying degrees
on FreeBSD and OpenBSD. The Tailscale iOS and Android apps use this repo's
code, but this repo doesn't contain the mobile GUI code.
The macOS, iOS, and Windows clients
use the code in this repository but additionally include small GUI
wrappers. The GUI wrappers on non-open source platforms are themselves
not open source.
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