DGen

DGen implements useful OTP building blocks — gen_server, a process registry, and more to come — as durable, highly-available primitives for a distributed system, with a focus on ease of use and minimal operator setup. If you already know gen_server or a process registry like :global or gproc, using DGen's equivalents should feel familiar; the difference is what's underneath: a strongly-consistent database (FoundationDB) instead of process memory, so state and coordination survive process, node, and even cluster restarts.

The replication protocol behind dgen_registry is exhaustively model-checked with TLA+/TLC — not just tested — as part of CI. See formal/README.md for the model, what it proves, and how to run it yourself.

What's here

• dgen_server — the gen_server programming model (same callbacks, same return shapes), backed by durable state and a durable message queue instead of process memory. Any number of processes, on any number of nodes, can consume from the same server concurrently. See the dgen_server design doc.
• dgen_registry — an OTP-compatible process registry: give a running process a logical name and find or message it by name from anywhere in the cluster, via the standard {via, dgen_registry, {RegistryName, LogicalName}} contract. See the dgen_registry design doc.

Both are built on the same idea: push state and coordination into a strongly-consistent backend, so the OTP programming model you already know keeps working even when a process, a node, or the whole cluster restarts.

Installation

Erlang

DGen can be installed by adding dgen to your list of dependencies in rebar.config:

{deps, [
    {dgen, "~> 0.4"}
]}.

Elixir

DGen can be installed by adding dgen to your list of dependencies in mix.exs:

def deps do
  [
    {:dgen, "~> 0.4"}
  ]
end

Documentation

• dgen_server design doc — programming model, message processing, locking, persisted state, crash behaviour, guarantees, and configuration.
• dgen_registry design doc — consistency model, replication, leadership handoff, guarantees, and configuration.
• formal/README.md — the TLA+ model of dgen_registry's replication protocol.
• API reference and getting-started guides: https://hexdocs.pm/dgen.
• CHANGELOG.md — release notes.

AI disclosure

DGen's development makes deliberate, disclosed use of AI tooling:

• Implementation. Substantial portions of the codebase — across both Erlang and Elixir — were built in close collaboration with large language models, from initial implementation through refactoring and documentation.
• Correctness. LLM-assisted code touching safety-critical logic doesn't get a pass on rigor — the opposite: dgen_registry's replication protocol is checked against a TLA+ model with TLC, exhaustively exploring every reachable interleaving of a bounded cluster rather than relying on test coverage alone. See formal/README.md.
• Design. The architecture, API surface, and consistency trade-offs are human-opinionated, shaped by hands-on experience operating comparable distributed systems — leader election, durable queues, CP-oriented registries — not left to a model's defaults.