storehouse.py

# pylint: disable=consider-using-with
"""Module to handle the storehouse."""
import threading

from kytos.core import log
from kytos.core.events import KytosEvent


class StoreHouse:
    """Class to handle storehouse."""

    @classmethod
    def __new__(cls, *args, **kwargs):
        # pylint: disable=unused-argument
        """Make this class a Singleton."""
        instance = cls.__dict__.get("__instance__")
        if instance is not None:
            return instance
        cls.__instance__ = instance = object.__new__(cls)
        return instance

    def __init__(self, controller):
        """Create a storehouse instance."""
        self.controller = controller
        self.namespace = "kytos.mef_eline.circuits"
        if "_lock" not in self.__dict__:
            self._lock = threading.Lock()
        if "box" not in self.__dict__:
            self.box = None
        self.list_stored_boxes()

    def get_data(self):
        """Return the box data."""
        if not self.box:
            return {}
        self.get_stored_box(self.box.box_id)
        return self.box.data

    def create_box(self):
        """Create a new box."""
        content = {
            "namespace": self.namespace,
            "callback": self._create_box_callback,
            "data": {},
        }
        event = KytosEvent(name="kytos.storehouse.create", content=content)
        self.controller.buffers.app.put(event)
        log.debug("Create box from storehouse.")

    def _create_box_callback(self, _event, data, error):
        """Execute the callback to handle create_box."""
        if error:
            log.error(f"Can't create box with namespace {self.namespace}")

        self.box = data
        log.debug(f"Box {self.box.box_id} was created in {self.namespace}.")

    def list_stored_boxes(self):
        """List all boxes using the current namespace."""
        name = "kytos.storehouse.list"
        content = {
            "namespace": self.namespace,
            "callback": self._get_or_create_a_box_from_list_of_boxes,
        }

        event = KytosEvent(name=name, content=content)
        self.controller.buffers.app.put(event)
        log.debug(f"Bootstraping storehouse box for {self.namespace}.")

    def _get_or_create_a_box_from_list_of_boxes(self, _event, data, _error):
        """Create a new box or retrieve the stored box."""
        if data:
            self.get_stored_box(data[0])
        else:
            self.create_box()

    def get_stored_box(self, box_id):
        """Get box from storehouse."""
        content = {
            "namespace": self.namespace,
            "callback": self._get_box_callback,
            "box_id": box_id,
            "data": {},
        }
        name = "kytos.storehouse.retrieve"
        event = KytosEvent(name=name, content=content)
        self._lock.acquire()  # Lock to avoid race condition
        log.debug(f'Lock {self._lock} acquired.')
        self.controller.buffers.app.put(event)
        log.debug(f"Retrieve box with {box_id} from {self.namespace}.")

    def _get_box_callback(self, _event, data, error):
        """Handle get_box method saving the box or logging with the error."""
        if error:
            log.error(f"Box {data.box_id} not found in {self.namespace}.")

        self.box = data
        self._lock.release()
        log.debug(f'Lock {self._lock} released.')
        log.debug(f'Box {self.box.box_id} was loaded from storehouse.')

    def save_evc(self, evc):
        """Save a EVC using the storehouse."""
        self._lock.acquire()  # Lock to avoid race condition
        log.debug(f"Lock {self._lock} acquired.")
        self.box.data[evc.id] = evc.as_dict()

        content = {
            "namespace": self.namespace,
            "box_id": self.box.box_id,
            "data": self.box.data,
            "callback": self._save_evc_callback,
        }

        event = KytosEvent(name="kytos.storehouse.update", content=content)
        self.controller.buffers.app.put(event)

    def _save_evc_callback(self, _event, data, error):
        """Display the save EVC result in the log."""
        self._lock.release()
        log.debug(f"Lock {self._lock} released.")
        if error:
            log.error(f"Can't update the {self.box.box_id}")

        log.debug(f"Box {data.box_id} was updated.")