Finitomata.Persistency.ETS (Finitomata v0.40.0)

Built-in in-memory Finitomata.Persistency adapter backed by a named ETS table.

It stores one {state, payload} snapshot per FSM (keyed by the FSM name) and reloads it when an FSM with the same name starts again. Because the table is owned by a long-lived process rather than by the FSM itself, snapshots survive the transient restart of an individual FSM (for example after a crash), which makes this adapter a zero-boilerplate fit for development, tests, and single-node deployments that only need durability for the lifetime of the node.

In-memory only

Snapshots are kept in ETS and are lost when the node stops. Use Finitomata.Persistency.DETS for durability across node restarts, or a custom Finitomata.Persistency implementation (for example via Finitomata.Persistency.Persistable) to target an external database.

Usage

Add the table owner to your supervision tree and point use Finitomata at this module:

children = [
  Finitomata.Persistency.ETS,
  {Finitomata.Supervisor, id: MyApp.Fsm}
]

defmodule MyApp.Order do
  use Finitomata, fsm: @fsm, persistency: Finitomata.Persistency.ETS
end

Start FSMs whose name equals the entity id so that the store and load keys line up:

Finitomata.start_fsm(MyApp.Fsm, MyApp.Order, order_id, %MyApp.Order{id: order_id})

Configuration

The ETS table name defaults to Finitomata.Persistency.ETS and can be overridden:

config :finitomata, Finitomata.Persistency.ETS, table: :my_fsm_snapshots

Summary

Functions

get(name)

Reads the snapshot stored for name, or nil

last_error(name)

Reads the last persisted failure for name, or nil

purge(name)

Removes the snapshot and the last error stored for name

start_link(opts \\ [])

Starts the process owning the snapshot table; add it to your supervision tree

table()

The ETS table name in use (configurable via config :finitomata, Finitomata.Persistency.ETS)