Rheo.Backend.ETS (rheo v1.0.0)

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In-memory ETS implementation of Rheo.Backend.

Always available (no optional dependency). Prefer for tests, Livebook, local demos, and ephemeral apps. Prefer Mongo, Ecto, Redis, or Mnesia when events must survive process or node restart.

Prefer the Rheo facade for application code. The opaque handle is this process's registered name (default Rheo.ETS), started via child_spec/1.

When to use

  • Unit and contract tests that need a real backend without external services
  • Livebook / Notebook prototypes
  • Single-node apps where loss on restart is acceptable

Do not use when durability or multi-node lease arbitration is required (durable: false, distributed: false).

Capabilities

  • durable: false — tables die with the owner GenServer / node
  • distributed: false — not shared across BEAM nodes
  • batch_writes: true, ordered_range_scan: true
  • replay: true, partitions: true, contiguous_frontier: true
  • secondary_indexes: false — query/2 filters in-process
  • notifications: false, atomic_compare_and_set: false

Tables

Per-instance protected ETS tables owned by this GenServer:

streams / events / groups / deliveries
event_ids / delivery_by_seq / open_deliveries

Options

Supervision example

children = [
  {Rheo, name: MyRheo, backend: Rheo.Backend.ETS}
]

Named handle:

children = [
  {Rheo, name: MyRheo, backend: {Rheo.Backend.ETS, name: MyRheo.ETS}}
]

Callback semantics are documented on Rheo.Backend.

Summary

Functions

child_spec(init_arg)

Child spec for the ETS GenServer (backend handle).

default_handle()

Default ETS handle name for the Rheo instance.

Functions

child_spec(init_arg)

@spec child_spec(keyword()) :: Supervisor.child_spec()

Child spec for the ETS GenServer (backend handle).

Arguments

  • opts — keyword options:

Examples

iex> spec = Rheo.Backend.ETS.child_spec(name: :demo_ets)
iex> {spec.id, elem(spec.start, 0), spec.type}
{{Rheo.Backend.ETS, :demo_ets}, Rheo.Backend.ETS, :worker}

Returns

A supervisor child spec map.

default_handle()

@spec default_handle() :: atom()

Default ETS handle name for the Rheo instance.

Examples

iex> Rheo.Backend.ETS.default_handle()
Rheo.ETS

Returns

A process name atom (Rheo.ETS).