v0.2.0

First minor release. Highlights:

Fixed

• Race: late NEIGHBOR_REPLY re-adding a dead peer to the active view (#1). State now keeps a small recently_lost deny-list of peer ids evicted via connection_lost/2; the reply handler rejects only replies whose sender is in that set, everything else is accepted as before. Found and reproduced by Lockstep.

Changed (breaking)

• HyParView.Transport callback signature: listen/2 now takes a 1-arity event_callback instead of a 2-arity deliver callback. Events are {:message, peer, msg} and {:peer_lost, peer}.

Added

• HyParView.Transport.TCP auto-signals {:peer_lost, peer} on TCP close — reactive recovery fires without applications needing to call connection_lost/2 themselves.
• TCP_NODELAY enabled on every Transport socket — short protocol messages no longer wait up to 40ms for Nagle. Found via the hyparview_pubsub_bench companion project.
• HyParView.subscribe/3 :replay option for late subscribers.
• HyParView.Telemetry.Metrics — pre-built Telemetry.Metrics definitions; drop into Prometheus / StatsD / any reporter. Optional dep on :telemetry_metrics ~> 1.0.

Tested

• HyParView.PartitionTest — partition + heal property tests.
• HyParView.ConnectionTest — Connection error-path coverage.
• HyParView.ConnectionLostRaceTest — H1 regression test.
• Coverage bumped to 89% (test-support modules excluded from the average).

See CHANGELOG.md for full notes and the upgrade impact of the breaking Transport change.

v0.1.0 — initial release

First release of hyparview, a clean Elixir implementation of the HyParView hybrid partial-view membership protocol from Leitão, Pereira, and Rodrigues (DSN 2007).

What's in the box

• HyParView.Peer — opaque peer identity (id + address)
• HyParView.Messages — the seven protocol messages from the paper
• HyParView.Protocol — versioned wire format with :safe decode
• HyParView.Config — paper-default configuration with validation
• HyParView.State — pure functional protocol core
• HyParView.Server — GenServer wrapping State with timers, transport, subscribers, telemetry
• HyParView.Transport — pluggable transport behaviour
• HyParView.Transport.Test — in-process transport for tests
• HyParView.Transport.TCP — :gen_tcp + per-peer :gen_statem connection
• HyParView.Telemetry — event catalog and prefix helpers

Quality gates

• 7 doctests, 14 properties, 93 tests
• mix credo --strict: clean
• mix dialyzer: clean (modulo two known-suppressed MapSet opacity false-positives)
• mix format --check-formatted: clean

Tested coverage

• Seven numbered view invariants (StateTest)
• Wire-format round-trip (ProtocolTest)
• JOIN + dual-TTL FORWARD_JOIN (JoinTest)
• DISCONNECT + NEIGHBOR + reactive recovery (RecoveryTest)
• SHUFFLE + SHUFFLE_REPLY (ShuffleTest)
• Active-view symmetry (SymmetryTest)
• Chaos + stress + determinism (ChaosTest)
• Multi-process integration via Transport.Test (IntegrationTest)
• Real-network integration via Transport.TCP (TCPTest)
• Edge cases: lone node, concurrent joins, larger cluster, subscriber down events (ComprehensiveTest)
• Telemetry events (TelemetryTest)

Install

def deps do
  [{:hyparview, "~> 0.1"}]
end

References

• Paper (DSN 2007)
• hexdocs

Out of scope for v0.1

• Plumtree (broadcast layer) — separate library
• Distributed registry / supervisor — see Horde
• TLS / auth — wrap the transport behaviour
• Auto-trigger of connection_lost from TCP-close — apps must call HyParView.connection_lost/2 themselves on failure for now