Exq.Middleware.Behaviour behaviour (exq v0.25.0)

Worker middleware configured through Exq's :middleware list.

Lifecycle callbacks run in the worker GenServer, not the Task executing the job, and return the pipeline. Prefer before_work/1, after_processed_work/1, and after_failed_work/1 for setup, cleanup, and notifications.

Use the optional around_perform/2 only when code must run inside the worker Task, such as attaching process-local context.

Summary

Callbacks

after_failed_work(%Exq.Middleware.Pipeline{})

Runs in the worker GenServer when the Task raises, exits, is killed, or is canceled.

after_processed_work(%Exq.Middleware.Pipeline{})

Runs in the worker GenServer after normal Task completion.

around_perform(%Exq.Middleware.Pipeline{}, function)

Wraps worker execution inside the Task, after job metadata is associated.

before_work(%Exq.Middleware.Pipeline{})

Runs in the worker GenServer before the worker Task starts.

Callbacks

after_failed_work(%Exq.Middleware.Pipeline{})

@callback after_failed_work(%Exq.Middleware.Pipeline{
  assigns: term(),
  event: term(),
  halted: term(),
  terminated: term(),
  worker_pid: term()
}) :: %Exq.Middleware.Pipeline{
  assigns: term(),
  event: term(),
  halted: term(),
  terminated: term(),
  worker_pid: term()
}

Runs in the worker GenServer when the Task raises, exits, is killed, or is canceled.

pipeline.assigns.error and pipeline.assigns.error_message describe the failure.

after_processed_work(%Exq.Middleware.Pipeline{})

@callback after_processed_work(%Exq.Middleware.Pipeline{
  assigns: term(),
  event: term(),
  halted: term(),
  terminated: term(),
  worker_pid: term()
}) :: %Exq.Middleware.Pipeline{
  assigns: term(),
  event: term(),
  halted: term(),
  terminated: term(),
  worker_pid: term()
}

Runs in the worker GenServer after normal Task completion.

pipeline.assigns.result contains the result returned by worker execution or its middleware.

around_perform(%Exq.Middleware.Pipeline{}, function)

(optional)

@callback around_perform(
  %Exq.Middleware.Pipeline{
    assigns: term(),
    event: term(),
    halted: term(),
    terminated: term(),
    worker_pid: term()
  },
  (%Exq.Middleware.Pipeline{
     assigns: term(),
     event: term(),
     halted: term(),
     terminated: term(),
     worker_pid: term()
   } ->
     {%Exq.Middleware.Pipeline{
        assigns: term(),
        event: term(),
        halted: term(),
        terminated: term(),
        worker_pid: term()
      }, term()})
) ::
  {%Exq.Middleware.Pipeline{
     assigns: term(),
     event: term(),
     halted: term(),
     terminated: term(),
     worker_pid: term()
   }, term()}

Wraps worker execution inside the Task, after job metadata is associated.

Both next.(pipeline) and this callback return {pipeline, result}. The first configured middleware is outermost.

Prefer the lifecycle callbacks unless Task-local execution is needed. Cleanup inside the Task is not guaranteed on hard kills or cancellation; use after_failed_work/1 when cleanup must survive Task termination.

After-work callbacks receive the returned assignments. On failure, they receive the last pipeline passed to next or returned by a completed callback.

Returning without calling next is treated as normal completion.

before_work(%Exq.Middleware.Pipeline{})

@callback before_work(%Exq.Middleware.Pipeline{
  assigns: term(),
  event: term(),
  halted: term(),
  terminated: term(),
  worker_pid: term()
}) :: %Exq.Middleware.Pipeline{
  assigns: term(),
  event: term(),
  halted: term(),
  terminated: term(),
  worker_pid: term()
}

Runs in the worker GenServer before the worker Task starts.

Prepare shared data in pipeline.assigns.