Restore an actor from a checkpoint if available and log any errors.

        This should only be called on workers that have just executed an actor
        creation task.

        Args:
            actor: The actor to restore from a checkpoint.

def _restore_and_log_checkpoint(self, actor):
        """Restore an actor from a checkpoint if available and log any errors.

        This should only be called on workers that have just executed an actor
        creation task.

        Args:
            actor: The actor to restore from a checkpoint.
        """
        actor_id = self._worker.actor_id
        try:
            checkpoints = ray.actor.get_checkpoints_for_actor(actor_id)
            if len(checkpoints) > 0:
                # If we found previously saved checkpoints for this actor,
                # call the `load_checkpoint` callback.
                checkpoint_id = actor.load_checkpoint(actor_id, checkpoints)
                if checkpoint_id is not None:
                    # Check that the returned checkpoint id is in the
                    # `available_checkpoints` list.
                    msg = (
                        "`load_checkpoint` must return a checkpoint id that " +
                        "exists in the `available_checkpoints` list, or eone.")
                    assert any(checkpoint_id == checkpoint.checkpoint_id
                               for checkpoint in checkpoints), msg
                    # Notify raylet that this actor has been resumed from
                    # a checkpoint.
                    (self._worker.raylet_client.
                     notify_actor_resumed_from_checkpoint(
                         actor_id, checkpoint_id))
        except Exception:
            # Checkpoint save or reload failed. Notify the driver.
            traceback_str = ray.utils.format_error_message(
                traceback.format_exc())
            ray.utils.push_error_to_driver(
                self._worker,
                ray_constants.CHECKPOINT_PUSH_ERROR,
                traceback_str,
                driver_id=self._worker.task_driver_id)