Changelog

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v0.4.2 (2026-10-04)

Enahancements

  • Support retrieving tenant via anonymous function

v0.4.1 (2026-09-04)

Bug fixes

  • Fixed a race where an unregister could delete a binding it didn't own, freeing a name twice under ordinary concurrency.
  • Fixed the DST harness's readiness poll hanging on a virtual clock deadline.
  • Fixed a lock holder that was busted mid-run releasing its successor's lock.
  • Fixed a lock holder that was busted mid-run overwriting its successor's writes.

Enhancements

  • dgen_registry is now stable, and no longer experimental.
  • The dgen_server lock is now fenced. A busted holder is refused at commit and its message is retried, so lock_timeout can be tuned for recovery speed. handle_locked/4 must be safe to run twice. See docs/design/dgen_server_design.md §4.4.
  • Added tests for lock_timeout and the consume_batch exit points.
  • dgen_registry_member rewritten as a gen_statem with explicit searching/assuming/leader/follower states. sys:get_state/1 now returns {State, Data}.
  • Leadership handoff sped up (~2x faster election window at 200k names) by cutting map allocations, shrinking the snapshot encoding, and deferring monitor setup off the critical path.
  • Expanded TLA+ model and DST invariants covering replication and leader handoff.
  • Added a per-registry connectivity option (provided_externally) to let a registry share another registry's distribution mesh instead of running its own. See docs/dgen_registry_design.md §4.6 and §8.

v0.4.0 (2026-07-12)

Enhancements

  • dgen_registry — a defined consistency model (still experimental). Full contract in docs/dgen_registry_design.md. Highlights:

    • CP and fenced — the leader is fenced on a backend key, so a deposed leader cannot commit; no split-brain, minority partitions refuse writes.
    • Singleton uniqueness across any single member failure; pids never persisted (~2 durable keys per registry).
    • Two-holder addressability — an acked registration is held by ≥2 members; tunable via register_replicas / replicate_timeout / strict_replication.
    • Dynamic membership with an automatic mesh — nodes join/leave by starting/stopping the registry; no external discovery.
    • Lock-free snapshot reads — whereis_name/1 is an ets:lookup/2 in the calling process (eventually-consistent snapshot; empty briefly after member restart).
    • Per-registration metadata — an index map + opaque data, set via register_name/3 / set_metadata/2, read via get_metadata/1 or get_metadata_consistent/1; lifetime is exactly the registration's (§4.7).
    • Indexed queries — query/2 / query_consistent/2 match AND-equal constraints over indexed attributes against a batch-consistent snapshot.
    • Durable presence — subscriptions (watch + notify queries under a SubId) push {dgen_presence, SubId, Events} on membership changes; stored durably, so they survive full cluster restarts.
    • Formally verified replication — core safety properties checked against a TLA+ model (formal/).

  • dgen_transaction (new behaviour) — owns a single backend transaction in its own process with caller-controlled retry; substrate for the registry's group commit.

  • dgen_server — consume_k documented; when consume_k > 1, inline call handling is disabled so batching stays in effect. priority_call/priority_cast still bypass the queue.

Behavioral notes

  • The registry may forcibly kill a registered process to enforce uniqueness. Register only restart-safe processes. Configurable via terminate_on_conflict (default true); see §5.6.

Breaking changes

  • dgen_registry:start_link/3 (SupName variant) removed — the registry supervisor is nameless by design; hold the returned pid instead.
  • elector_name/1 removed in favor of elector_pid/1; member_name/1 and names_table/1 are now identity functions.
  • register_name/2,3 exits on call timeout instead of returning no — no is now strictly an adjudicated verdict. Timeout configurable via register_timeout (default 5000 ms).

v0.3.0 (2026-06-17)

Enhancements

  • Transactional callbacks — optional handle_cast_tx/3, handle_call_tx/4, handle_info_tx/3 receive a tx_ctx() (open transaction + directory) so callbacks can read/write keys atomically with the state commit.
  • lock_timeout option for dgen_server — backstop timer clears a stale distributed lock left by a killed consumer. Default infinity (old behavior); dgen_registry uses 6000 ms.
  • dgen_registry (experimental) — OTP-compatible process registry over the storage backend, addressed via {via, dgen_registry, {Name, LogicalName}}. Writes and consistent reads go through an elected leader; whereis_name/1 is a local snapshot read. Partition recovery is token-fenced so stale member_down messages can't undo a rejoin.

Breaking changes

  • DGenServer → DGen.Server (lib/dgen/server.ex).
  • handle_locked/3 → handle_locked/4 — a db_ctx() map is prepended as the first argument.

v0.2.0 (2026-04-05)

Enhancements

  • Dead-letter queue — opt-in via dead_letter_threshold; messages crashing the consumer that many times move to a DLQ, callers raise {dead_letter, N}, and the optional handle_dead_letter/2 callback fires.
  • dgen_server:outbox_cast/1,2 — returns a closure for enqueuing a cast atomically inside the caller's own backend transaction.

v0.1.0 (2026-02-22)

Initial release.