Generate and expose a uuid for basic producers

The UUID aids in identifying orphaned jobs or churning producers.

lib/oban/engines/basic.ex

@@ -26,6 +26,7 @@ defmodule Oban.Engines.Basic do
           |> Map.new()
           |> Map.put_new(:paused, false)
           |> Map.put_new(:refresh_interval, :timer.seconds(30))
+          |> Map.put_new(:uuid, Ecto.UUID.generate())
           |> Map.merge(%{name: conf.name, node: conf.node})
           |> Map.merge(%{started_at: utc_now(), updated_at: utc_now()})
 
@@ -110,7 +111,7 @@ defmodule Oban.Engines.Basic do
       |> select([j, _], j)
 
     updates = [
-      set: [state: "executing", attempted_at: utc_now(), attempted_by: [meta.node]],
+      set: [state: "executing", attempted_at: utc_now(), attempted_by: [meta.node, meta.uuid]],
       inc: [attempt: 1]
     ]
 

test/oban_test.exs

@@ -112,7 +112,7 @@ defmodule ObanTest do
 
       alpha_state = Oban.check_queue(name, queue: :alpha)
 
-      assert %{limit: 1, node: _, paused: false} = alpha_state
+      assert %{limit: 1, node: _, paused: false, uuid: _} = alpha_state
       assert %{queue: "alpha", running: [_], started_at: %DateTime{}} = alpha_state
 
       assert %{limit: 2, queue: "gamma", running: [_]} = Oban.check_queue(name, queue: :gamma)