Relocate the overlay peer-rendezvous subsystem out of the overloaded
src/discovery/ tree into two focused, independent homes: src/nostr/
(relay-mediated overlay endpoint advertise/resolve/auto-mesh plus NAT
traversal) and src/mdns/ (link-local DNS-SD rendezvous). The two
subsystems are independent, so they get separate homes rather than
sharing one.
Drop the ambiguous "Discovery" stem from their identifiers in favor of
"Rendezvous": NostrDiscovery -> NostrRendezvous, LanDiscovery ->
LanRendezvous, and the matching config, policy, field, and method names.
The former src/discovery.rs handoff types (EstablishedTraversal,
BootstrapHandoffResult, the punch-packet helpers) fold into
src/nostr/handoff and stay reachable via the crate-root re-exports.
Pure relocation and rename: no logic, wire-format, config-key, metric,
or tracing-target changes. The operator-facing node.rendezvous.nostr.*
and node.rendezvous.lan.* config keys and the fips-overlay-v1 advert
namespace are byte-identical. cargo fmt/build/clippy clean; lib test
suite 1547 passing (baseline unchanged).
Move PeerAclReloader onto the Reloadable trait: its ACL snapshot is now
published through an arc_swap::ArcSwap so the authorization hot path reads
it without locking, and the former check_reload becomes the trait's
reload(). The node tick calls self.peer_acl.reload().await.
Wire the host map into the tick as well. The host map snapshot was
previously taken once at construction and never polled; it now hot-reloads
on /etc/fips/hosts mtime changes once per tick, alongside the ACL, so
hostname display reflects edits without a restart.
The path_mtu_lookup cache (event-driven, populated from observed traffic)
and the nostr_discovery subsystem (an async spawned task) are deliberately
left off the trait: neither reloads from a backing file, so a no-op reload()
would be misleading. The rationale is documented on the trait module.
The host map and the ACL's embedded alias reloader still stat /etc/fips/hosts
independently each tick. A single small-file stat per tick is cheap, so the
duplicate is left in place; sharing one mtime observation between the two is
a possible future cleanup.
Tests: a node-level test exercises the host-map tick reload end to end
through peer_display_name; the ACL reloader tests are updated to drive the
async reload().
Add a `Reloadable` trait that normalizes the node's reloadable
configuration/resource pattern onto a single contract built around an
`arc_swap::ArcSwap` snapshot: a lock-free `load()` for the hot read path
and an async `reload()` that re-reads the backing source and atomically
swaps in a fresh snapshot. The trait carries the canonical Arc-wrapper
template documentation (single-writer node tick, many-reader hot path,
whole-snapshot swap so readers never observe a partial update).
Migrate the host map to this trait via a new `HostMapReloadable` that
reuses the existing load/merge/mtime helpers in upper::hosts. The Node
`host_map` field changes from `Arc<HostMap>` to `HostMapReloadable`, and
`peer_display_name` reads through a lock-free guard. The initial snapshot
is byte-identical to the previous construction, so behavior is unchanged.
The host map is still snapshotted once at construction and not polled;
`reload()` is exercised only by unit tests for now. Wiring the periodic
poll into the node tick, and deduplicating the hosts-file stat against
the ACL reloader's embedded copy, is left as a follow-up.
Add `arc-swap` as a dependency. Unit tests cover initial load (base +
file, base only), change/no-change/deletion/creation detection,
base-preserved-on-reload, and equivalence of the initial snapshot to the
pre-migration construction.
Johnathan Corgan