| # Copyright 2013 The Chromium Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| import cPickle |
| import google.appengine.ext.db as db |
| import logging |
| import traceback |
| |
| |
| _MAX_ENTITY_SIZE = 1024*1024 |
| |
| |
| # A collection of the data store models used throughout the server. |
| # These values are global within datastore. |
| |
| class PersistentObjectStoreItem(db.Model): |
| pickled_value = db.BlobProperty() |
| |
| @classmethod |
| def CreateKey(cls, namespace, key): |
| path = '%s/%s' % (namespace, key) |
| try: |
| return db.Key.from_path(cls.__name__, path) |
| except Exception: |
| # Probably AppEngine's BadValueError for the name being too long, but |
| # it's not documented which errors can actually be thrown here, so catch |
| # 'em all. |
| raise ValueError( |
| 'Exception thrown when trying to create db.Key from path %s: %s' % ( |
| path, traceback.format_exc())) |
| |
| @classmethod |
| def CreateItem(cls, namespace, key, value): |
| pickled_value = cPickle.dumps(value) |
| if len(pickled_value) > _MAX_ENTITY_SIZE: |
| logging.warn('Refusing to create entity greater than 1 MB in size: %s/%s' |
| % (namespace, key)) |
| return None |
| return PersistentObjectStoreItem(key=cls.CreateKey(namespace, key), |
| pickled_value=pickled_value) |
| |
| def GetValue(self): |
| return cPickle.loads(self.pickled_value) |
