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from beaker._compat import pickle
import logging
from datetime import datetime
from beaker.container import OpenResourceNamespaceManager, Container
from beaker.exceptions import InvalidCacheBackendError
from beaker.synchronization import null_synchronizer
log = logging.getLogger(__name__)
db = None
class GoogleNamespaceManager(OpenResourceNamespaceManager):
tables = {}
@classmethod
def _init_dependencies(cls):
global db
if db is not None:
return
try:
db = __import__('google.appengine.ext.db').appengine.ext.db
except ImportError:
raise InvalidCacheBackendError("Datastore cache backend requires the "
"'google.appengine.ext' library")
def __init__(self, namespace, table_name='beaker_cache', **params):
"""Creates a datastore namespace manager"""
OpenResourceNamespaceManager.__init__(self, namespace)
def make_cache():
table_dict = dict(created=db.DateTimeProperty(),
accessed=db.DateTimeProperty(),
data=db.BlobProperty())
table = type(table_name, (db.Model,), table_dict)
return table
self.table_name = table_name
self.cache = GoogleNamespaceManager.tables.setdefault(table_name, make_cache())
self.hash = {}
self._is_new = False
self.loaded = False
self.log_debug = logging.DEBUG >= log.getEffectiveLevel()
# Google wants namespaces to start with letters, change the namespace
# to start with a letter
self.namespace = 'p%s' % self.namespace
def get_access_lock(self):
return null_synchronizer()
def get_creation_lock(self, key):
# this is weird, should probably be present
return null_synchronizer()
def do_open(self, flags, replace):
# If we already loaded the data, don't bother loading it again
if self.loaded:
self.flags = flags
return
item = self.cache.get_by_key_name(self.namespace)
if not item:
self._is_new = True
self.hash = {}
else:
self._is_new = False
try:
self.hash = pickle.loads(str(item.data))
except (IOError, OSError, EOFError, pickle.PickleError):
if self.log_debug:
log.debug("Couln't load pickle data, creating new storage")
self.hash = {}
self._is_new = True
self.flags = flags
self.loaded = True
def do_close(self):
if self.flags is not None and (self.flags == 'c' or self.flags == 'w'):
if self._is_new:
item = self.cache(key_name=self.namespace)
item.data = pickle.dumps(self.hash)
item.created = datetime.now()
item.accessed = datetime.now()
item.put()
self._is_new = False
else:
item = self.cache.get_by_key_name(self.namespace)
item.data = pickle.dumps(self.hash)
item.accessed = datetime.now()
item.put()
self.flags = None
def do_remove(self):
item = self.cache.get_by_key_name(self.namespace)
item.delete()
self.hash = {}
# We can retain the fact that we did a load attempt, but since the
# file is gone this will be a new namespace should it be saved.
self._is_new = True
def __getitem__(self, key):
return self.hash[key]
def __contains__(self, key):
return key in self.hash
def __setitem__(self, key, value):
self.hash[key] = value
def __delitem__(self, key):
del self.hash[key]
def keys(self):
return self.hash.keys()
class GoogleContainer(Container):
namespace_class = GoogleNamespaceManager
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