DGen

DGen provides software building blocks that marry the OTP ethos with a reliable distributed system, with a focus on ease of use and minimal operator setup. We implement a durable and fully distributed gen_server-like with dgen_server (Elixir: DGen.Server) and a distributed process registry with dgen_registry (Elixir: DGen.Registry).

DGen is implemented against the FoundationDB API. Any conforming database could, in theory, be substituted, but for now FDB is the only implemented backend.

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.x"}
]}.

Find the most recent version number on Hex.

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.
• eta — dgen_registry is partally tested with Deterministic Simulation Testing, to assist in verification of the actual implementation of the TLA+ model, including its invariants. The framework for driving the simulation was extracted to a separate library for general use.
• API reference and getting-started guides: https://hexdocs.pm/dgen.
• CHANGELOG.md — release notes.

AI full disclosure

• This software is developed with strong assistance from LLMs and with humans leading the ideas, testing, and debugging. We say this openly because it shaped how the project was built. If you are not happy with AI-developed code, this software is not for you. This disclosure was adopted from antirez/ds4.
• We strive to write and edit the documentation for human consumption. LLM-speak will eventually be rooted out in favor of imperfect human writing. Documentation generated wholly by LLMs must be annotated as such.