+class TemporaryReservationManager:
+ """A temporary resource reservation manager.
+
+ This is used to reserve resources in a job, before using them, making sure
+ other jobs cannot get them in the meantime.
+
+ """
+ def __init__(self):
+ self._ec_reserved = {}
+
+ def Reserved(self, resource):
+ for holder_reserved in self._ec_reserved.items():
+ if resource in holder_reserved:
+ return True
+ return False
+
+ def Reserve(self, ec_id, resource):
+ if self.Reserved(resource):
+ raise errors.ReservationError("Duplicate reservation for resource: %s." %
+ (resource))
+ if ec_id not in self._ec_reserved:
+ self._ec_reserved[ec_id] = set([resource])
+ else:
+ self._ec_reserved[ec_id].add(resource)
+
+ def DropECReservations(self, ec_id):
+ if ec_id in self._ec_reserved:
+ del self._ec_reserved[ec_id]
+
+ def GetReserved(self):
+ all_reserved = set()
+ for holder_reserved in self._ec_reserved.values():
+ all_reserved.update(holder_reserved)
+ return all_reserved
+
+ def Generate(self, existing, generate_one_fn, ec_id):
+ """Generate a new resource of this type
+
+ """
+ assert callable(generate_one_fn)
+
+ all_elems = self.GetReserved()
+ all_elems.update(existing)
+ retries = 64
+ while retries > 0:
+ new_resource = generate_one_fn()
+ if new_resource is not None and new_resource not in all_elems:
+ break
+ else:
+ raise errors.ConfigurationError("Not able generate new resource"
+ " (last tried: %s)" % new_resource)
+ self.Reserve(ec_id, new_resource)
+ return new_resource
+
+