A UDP service's socket is kept as a listener like a TCP one, the
protocol part of what must match: on a reload a new UDP service on the
same address takes it over. It is the way the old service's sessions
answer as well, and they go on answering through it; the new service
reads what comes, a datagram of an old session forwarded to it as
before, sessions being found by the service's and the client's
addresses whichever service made them. The socket stays open while the
old sessions do.
The takeover case keeps a udppm session going through three reloads
and wants every datagram back; with the build before this datagrams
were lost.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A service's TCP listening socket is kept as a listener: when a reload
commits, before the old services are told to stop, each new service
takes over the listener of an older configuration's service on the same
address, port, network namespace and device with the same -ol options.
It skips socket() and bind(), calling only listen() again for its own
backlog, and logs "Accepting connections, taken over". The old service
stops accepting at its next poll and lets go of the socket; whoever
lets go last closes it, unlinking a Unix socket's path.
So a service staying where it was no longer leaves a gap: before, the
old one closed its socket and the new one opened another, and a
connection queued on the old socket was reset. UDP services, whose
clients read from the service's socket, and two services of the same
configuration on one address keep their own sockets as before.
A test case makes requests nonstop through three reloads and wants none
refused or reset; against the build before this, connections were
reset. The reload case no longer waits out the switch. SIGUSR1 in
3proxy(8) describes how a reload behaves now.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
