Bug: Lack of exception trace

[hhubert6]

This behavior happen due to reading state of dead live view (while saving it)

:ok <- StateActions.maybe_save_state!(updated_trace),

which stops trace handling, raises error and crashes gen_server. When gen_server is started again all other traces that were stored in a gen_server inbox are lost and thus I assume the handle_info which ended with exception with them.

def handle_cast({:new_trace, {_, pid, type, {module, fun, _}, _, return_ts}, _n}, state)
    when fun in @allowed_callbacks and type in [:return_from, :exception_from] do
  with trace_key <- {pid, module, fun},
       {ref, trace, ts} <- get_trace_record(state, trace_key),
       execution_time <- calculate_execution_time(return_ts, ts),
       params <- %{execution_time: execution_time, type: type},
       {:ok, updated_trace} <- TraceActions.update_trace(trace, params),
       {:ok, ref} <- TraceActions.persist_trace(updated_trace, ref),
       :ok <- StateActions.maybe_save_state!(updated_trace),
       :ok <- TraceActions.publish_trace(updated_trace, ref) do
    {:noreply, delete_trace_record(state, trace_key)}
  else
    :trace_record_not_found ->
      {:noreply, state}

    {:error, err} ->
      raise "Error while handling trace: #{inspect(err)}"
  end
end

Simplest solution is to keep tracing flow despite of the result of saving state

_ <- StateActions.maybe_save_state!(updated_trace),

[kraleppa]

Looking good - is possible to test if exception trace does appear?

[hhubert6]

Looking good - is possible to test if exception trace does appear?

I've added a usual scenario of clicking crash button in LiveDebuggerDev.LiveViews.Main. Recreating the situation in which this exact bug occurred is very tedious so I didn't try to make it in test. Or do you insist to do it?

cc @kraleppa

[kraleppa]

@hhubert6 I think it's fine

Looking good - is possible to test if exception trace does appear?

I've added a usual scenario of clicking crash button in LiveDebuggerDev.LiveViews.Main. Recreating the situation in which this exact bug occurred is very tedious so I didn't try to make it in test. Or do you insist to do it?

cc @kraleppa

I think it's good enough 👍