def string_from_id(self, rc_id): """The reverse of the id_from_string() method. Given a supplied numeric identifier for a resource class, we look up the corresponding string representation, either in the list of standard resource classes or via a DB lookup. The results of these DB lookups are cached since the lookups are so frequent. :param rc_id: The numeric representation of the resource class to look up a string identifier for. :returns string identifier for the resource class, or None, if no such resource class was found in the list of standard resource classes or the resource_classes database table. :raises `exception.ResourceClassNotFound` if rc_id cannot be found in either the standard classes or the DB. """ # First check the fields.ResourceClass.STANDARD values try: return fields.ResourceClass.STANDARD[rc_id] except IndexError: pass with lockutils.lock(_LOCKNAME): if rc_id in self.str_cache: return self.str_cache[rc_id] # Otherwise, check the database table _refresh_from_db(self.ctx, self) if rc_id in self.str_cache: return self.str_cache[rc_id] raise exception.ResourceClassNotFound(resource_class=rc_id)
def id_from_string(self, rc_str): """Given a string representation of a resource class -- e.g. "DISK_GB" or "IRON_SILVER" -- return the integer code for the resource class. For standard resource classes, this integer code will match the list of resource classes on the fields.ResourceClass field type. Other custom resource classes will cause a DB lookup into the resource_classes table, however the results of these DB lookups are cached since the lookups are so frequent. :param rc_str: The string representation of the resource class to look up a numeric identifier for. :returns integer identifier for the resource class, or None, if no such resource class was found in the list of standard resource classes or the resource_classes database table. :raises `exception.ResourceClassNotFound` if rc_str cannot be found in either the standard classes or the DB. """ # First check the standard resource classes if rc_str in fields.ResourceClass.STANDARD: return fields.ResourceClass.STANDARD.index(rc_str) with lockutils.lock(_LOCKNAME): if rc_str in self.id_cache: return self.id_cache[rc_str] # Otherwise, check the database table _refresh_from_db(self.ctx, self) if rc_str in self.id_cache: return self.id_cache[rc_str] raise exception.ResourceClassNotFound(resource_class=rc_str)
def all_from_string(self, rc_str): """Given a string representation of a resource class -- e.g. "DISK_GB" or "CUSTOM_IRON_SILVER" -- return all the resource class info. :param rc_str: The string representation of the resource class for which to look up a resource_class. :returns: dict representing the resource class fields, if the resource class was found in the list of standard resource classes or the resource_classes database table. :raises: `exception.ResourceClassNotFound` if rc_str cannot be found in either the standard classes or the DB. """ # First check the standard resource classes if rc_str in fields.ResourceClass.STANDARD: return { 'id': fields.ResourceClass.STANDARD.index(rc_str), 'name': rc_str, 'updated_at': None, 'created_at': None } with lockutils.lock(_LOCKNAME): if rc_str in self.all_cache: return self.all_cache[rc_str] # Otherwise, check the database table _refresh_from_db(self.ctx, self) if rc_str in self.all_cache: return self.all_cache[rc_str] raise exception.ResourceClassNotFound(resource_class=rc_str)