The magicsock derpReader was holding onto 65KB for each DERP
connection forever, just in case.
Make the derp{,http}.Client be in charge of memory instead. It can
reuse its bufio.Reader buffer space.
This lets a trusted DERP client that knows a pre-shared key subscribe
to the connection list. Upon subscribing, they get the current set
of connected public keys, and then all changes over time.
This lets a set of DERP server peers within a region all stay connected to
each other and know which clients are connected to which nodes.
Updates #388
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This avoids the server blocking on misbehaving or heavily contended
clients. We attempt to drop from the head of the queue to keep
overall queueing time lower.
Also:
- fixes server->client keepalives, which weren't happening.
- removes read rate-limiter, deferring instead to kernel-level
global limiter/fair queuer.
Signed-off-by: David Anderson <dave@natulte.net>
This lets us publish sets of vars that are breakdowns along one
dimension in a format that Prometheus and Grafana natively know
how to do useful things with.
Signed-off-by: David Anderson <dave@natulte.net>
