import re from contextlib import suppress from itertools import groupby from typing import Iterable, List, Set from psycopg2.errorcodes import UNIQUE_VIOLATION from sqlalchemy.exc import IntegrityError from ereuse_devicehub.db import db from ereuse_devicehub.resources.device.exceptions import NeedsId from ereuse_devicehub.resources.device.models import Component, Computer, Device from ereuse_devicehub.resources.event.models import Add, Remove from teal.db import ResourceNotFound class Sync: """Synchronizes the device and components with the database.""" @classmethod def run(cls, device: Device, components: Iterable[Component] or None) -> (Device, List[Add or Remove]): """ Synchronizes the device and components with the database. Identifies if the device and components exist in the database and updates / inserts them as necessary. This performs Add / Remove as necessary. :param device: The device to add / update to the database. :param components: Components that are inside of the device. This method performs Add and Remove events so the device ends up with these components. Components are added / updated accordingly. If this is empty, all components are removed. If this is None, it means that there is no info about components and the already existing components of the device (in case the device already exists) won't be touch. :return: A tuple of: 1. The device from the database (with an ID) whose ``components`` field contain the db version of the passed-in components. 2. A list of Add / Remove (not yet added to session). """ db_device, _ = cls.execute_register(device) db_components, events = [], [] if components is not None: # We have component info (see above) blacklist = set() # type: Set[int] not_new_components = set() for component in components: db_component, is_new = cls.execute_register(component, blacklist, parent=db_device) db_components.append(db_component) if not is_new: not_new_components.add(db_component) # We only want to perform Add/Remove to not new components events = cls.add_remove(db_device, not_new_components) db_device.components = db_components return db_device, events @classmethod def execute_register(cls, device: Device, blacklist: Set[int] = None, parent: Computer = None) -> (Device, bool): """ Synchronizes one device to the DB. This method tries to create a device into the database, and if it already exists it returns a "local synced version", this is the same ``device`` you passed-in but with updated values from the database one (like the id value). When we say "local" we mean that if, the device existed on the database, we do not "touch" any of its values on the DB. :param device: The device to synchronize to the DB. :param blacklist: A set of components already found by Component.similar_one(). Pass-in an empty Set. :param parent: For components, the computer that contains them. Helper used by Component.similar_one(). :return: A tuple with: 1. A synchronized device with the DB. It can be a new device or an already existing one. 2. A flag stating if the device is new or it existed already in the DB. :raise NeedsId: The device has not any identifier we can use. To still create the device use ``force_creation``. :raise DatabaseError: Any other error from the DB. """ # Let's try to create the device if not device.hid and not device.id: # We won't be able to surely identify this device if isinstance(device, Component): with suppress(ResourceNotFound): # Is there a component similar to ours? db_component = device.similar_one(parent, blacklist) # We blacklist this component so we # ensure we don't get it again for another component # with the same physical properties blacklist.add(db_component.id) return cls.merge(device, db_component), False else: raise NeedsId() try: with db.session.begin_nested(): # Create transaction savepoint to auto-rollback on insertion err # Let's try to insert or update db.session.add(device) db.session.flush() except IntegrityError as e: if e.orig.diag.sqlstate == UNIQUE_VIOLATION: db.session.rollback() # This device already exists in the DB field, value = ( x.replace('(', '').replace(')', '') for x in re.findall('\(.*?\)', e.orig.diag.message_detail) ) db_device = Device.query.filter_by(**{field: value}).one() # type: Device return cls.merge(device, db_device), False else: raise e else: return device, True # Our device is new @classmethod def merge(cls, device: Device, db_device: Device): """ Copies the physical properties of the device to the db_device. """ for field_name, value in device.physical_properties.items(): if value is not None: setattr(db_device, field_name, value) return db_device @classmethod def add_remove(cls, device: Device, components: Set[Component]) -> List[Add or Remove]: """ Generates the Add and Remove events (but doesn't add them to session). :param device: A device which ``components`` attribute contains the old list of components. The components that are not in ``components`` will be Removed. :param components: List of components that are potentially to be Added. Some of them can already exist on the device, in which case they won't be re-added. :return: A list of Add / Remove events. """ # Note that we create the Remove events before the Add ones events = [] old_components = set(device.components) adding = components - old_components if adding: # For the components we are adding, let's remove them from their old parents def g_parent(component: Component) -> int: return component.parent or Computer(id=0) # Computer with id 0 is our Identity for parent, _components in groupby(sorted(adding, key=g_parent), key=g_parent): if parent.id != 0: # Is not Computer Identity events.append(Remove(device=parent, components=list(_components))) return events