Stamp every registered connection and in-flight dial with a network
generation, bumped by MarkNetworkChange, which replaces the immediate
full sweep with one delayed by a configurable 500ms. The sweep then
cuts only registrations older than the last change: subsystems that
redialed on their own hold fresh-generation connections and survive,
so the callers no longer need cancellation logic around the sweep.
A connection inherits its dial's generation, because the socket was
bound to the network that was default when the dial started.
This fixes the sweep being cancelled by the engine's management-level
reconnect while the relay was still down, and lets the mobile
notifiers shrink to plain forwarders.
WrapDialContext and WrapConn registered the dial and the connection
independently, so a sweep landing between the dial finishing and WrapConn
cancelled only the dial registration: the connection dialed on the old
network entered the fresh registry and survived the network change.
Replace the pair with a Dial handle. Sweep marks pending dials under the
sweeper mutex, and WrapConn decides under the same mutex: a swept dial's
connection is closed and ErrSwept returned, so the caller redials on the
new network; otherwise the connection transfers to the registry with no
window in between.
connPair closed the accepted connection right after the handshake, so the
reads in TestSweepClosesRegisteredConns failed on the peer's own close
rather than on the sweep. The test passed even with Sweep's close loop
removed. Hold the peer until cleanup so the read errors come from Sweep.
Adding OnStateChanged to the gomobile interface forces every Swift
implementation to grow the method before the app builds again. Drop it
from the iOS binding for now — the adapter satisfies the internal
listener with a no-op and the legacy per-state callbacks keep firing —
so the app upgrades on its own schedule. The state constants stay
exported for that follow-up.
Zoltán Papp