ExMaude.Backend.Port (ExMaude v0.3.0)

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Port-based backend for ExMaude.

This backend communicates with Maude via an Erlang Port over plain pipes, passing -interactive so Maude prints its prompt for response detection (the same mode the C-Node and NIF backends use).

Features

  • Full process isolation - Maude crashes don't affect the BEAM
  • Works with any Maude installation
  • No native code compilation required

Trade-offs

  • Higher latency than the NIF backend due to port messaging and text parsing
  • Regex-based error detection
  • Larger memory footprint per worker

Configuration

config :ex_maude,
  backend: :port,
  use_pty: false  # Set to true to wrap Maude in a PTY (script/unbuffer)

Timeouts and worker lifecycle

Each command carries its own timeout. When it fires, the caller receives {:error, %ExMaude.Error{type: :timeout}} and the worker stops with {:shutdown, :command_timeout} so the pool replaces it with a fresh process. Maude has no way to cancel an in-flight computation, so a timed-out session is in an indeterminate state — reusing it could deliver the previous command's response to the next caller.

Summary

Types

pending()

The in-flight command, if any.

t()

Internal state for the Port backend GenServer.

Functions

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

Types

pending()

@type pending() :: %{
  from: GenServer.from(),
  ref: reference(),
  timer: reference(),
  timeout: pos_integer()
}

The in-flight command, if any.

The ref ties the pending command to its {:command_timeout, ref} timer message: a timer that fires after its command completed carries a stale ref and is ignored instead of cutting into the next command.

t()

@type t() :: %ExMaude.Backend.Port{
  buffer: String.t() | nil,
  maude_path: String.t() | nil,
  os_pid: non_neg_integer() | nil,
  pending: pending() | nil,
  port: port() | nil
}

Internal state for the Port backend GenServer.

Functions

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

See Supervisor.