为什么在 Ecto 测试中获取锁不起作用？

Question

鉴于此 Ecto 测试：

test "fails to acquire lock" do
  %{rows: [[lock_acquired]]} = Ecto.Adapters.SQL.query!(Repo, "SELECT pg_try_advisory_lock()", [1337], [])
  assert lock_acquired

  %{rows: [[lock_acquired]]} = Ecto.Adapters.SQL.query!(Repo, "SELECT pg_try_advisory_xact_lock()", [1337], [])
  refute lock_acquired
end

没用。试图 pg_try_advisory_xact_lock 的第二行也设法做到了。

我实际上尝试过：

test "fails to acquire lock" do
  parent = self()
  t = Task.async(fn ->
    Ecto.Adapters.SQL.Sandbox.allow(Repo, parent, self())
    Ecto.Adapters.SQL.query!(ChargingIo.Repo, "SELECT pg_try_advisory_lock()", [1337], [])
    :timer.sleep(1_000)
  end)

  :timer.sleep(100)
  %{rows: [[lock_acquired]]} = Ecto.Adapters.SQL.query!(Repo, "SELECT pg_try_advisory_xact_lock()", [1337], [])
  Task.await(t)
  refute lock_acquired
end

想测试来自另一个进程的锁定是否能够阻止当前进程的锁定。

有趣的是，所有这些在开发控制台中都按预期工作。

欢迎提出想法！

Answer 1

好的，找到解决方案了。

setup do
  Ecto.Adapters.SQL.Sandbox.mode(Repo, :auto)
end

test "fails gracefuly when already locked" do
  t = Task.async(fn ->
    %{rows: [[lock_acquired]]} = Ecto.Adapters.SQL.query!(Repo, "SELECT pg_try_advisory_lock()", [1337], []) |> IO.inspect
    assert lock_acquired
    :timer.sleep(1_000)
  end)

  :timer.sleep(100)
  %{rows: [[lock_acquired]]} = Ecto.Adapters.SQL.query!(Repo, "SELECT pg_try_advisory_xact_lock()", [1337], []) |> IO.inspect
  refute lock_acquired

  Task.await(t)
end

看来我需要在设置中使用 :auto，如 https://medium.com/@qertoip/making-sense-of-ecto-2-sql-sandbox-and-connection-ownership-modes-b45c5337c6b7 中所述。

为什么在 Ecto 测试中获取锁不起作用？

Why acquiring lock in Ecto tests doesn't work?

elixir

ecto