def get_scatter_prop(element_list):
""" Gets the scatter property for an entity's key path.
This will return a property for only a small percentage of entities.
Args:
element_list: A list of entity_pb.Path_Element objects.
Returns:
An entity_pb.Property object or None.
"""
def id_from_element(element):
if element.has_name():
return element.name()
elif element.has_id():
return str(element.id())
else:
return ''
to_hash = ''.join([id_from_element(element) for element in element_list])
full_hash = mmh3.hash(to_hash)
hash_bytes = struct.pack('i', full_hash)[0:2]
hash_int = struct.unpack('H', hash_bytes)[0]
if hash_int >= dbconstants.SCATTER_PROPORTION:
return None
scatter_property = entity_pb.Property()
scatter_property.set_name('__scatter__')
scatter_property.set_meaning(entity_pb.Property.BYTESTRING)
scatter_property.set_multiple(False)
property_value = scatter_property.mutable_value()
property_value.set_stringvalue(hash_bytes)
return scatter_property
def _GetScatterProperty(entity_proto):
"""Gets the scatter property for an object.
For ease of implementation, this is not synchronized with the actual
value on the App Engine server, but should work equally well.
Note: This property may change, either here or in production. No client
other than the mapper framework should rely on it directly.
Returns:
The PropertyValue of the scatter property or None if this entity should not
have a scatter property.
"""
hash_obj = _MD5_FUNC()
for element in entity_proto.key().path().element_list():
if element.has_name():
hash_obj.update(element.name())
elif element.has_id():
hash_obj.update(str(element.id()))
hash_bytes = hash_obj.digest()[0:2]
(hash_int, ) = struct.unpack('H', hash_bytes)
if hash_int >= _SCATTER_PROPORTION:
return None
scatter_property = entity_pb.Property()
scatter_property.set_name('__scatter__')
scatter_property.set_meaning(entity_pb.Property.BYTESTRING)
scatter_property.set_multiple(False)
property_value = scatter_property.mutable_value()
property_value.set_stringvalue(hash_bytes)
return scatter_property
def _get_scatter_property(entity_proto):
key_name = entity_proto.key().path().element_list()[-1].name()
if key_name in key_names_to_vals:
scatter_property = entity_pb.Property()
scatter_property.set_name(datastore_types.SCATTER_SPECIAL_PROPERTY)
scatter_property.set_meaning(entity_pb.Property.BYTESTRING)
scatter_property.set_multiple(False)
property_value = scatter_property.mutable_value()
property_value.set_stringvalue(str(key_names_to_vals[key_name]))
return scatter_property
'Values for property %s have mismatched types: %s (a %s) and '
'%s (a %s).' % (name, values[0], proptype, v, typename(v)))
elif (isinstance(v, Key) and not v.has_id_or_name()):
raise datastore_errors.BadValueError(
'Incomplete key found for reference property %s.' % name)
except (KeyError, ValueError, TypeError, IndexError, AttributeError), msg:
raise datastore_errors.BadValueError(
'Error type checking values for property %s: %s' % (name, msg))
if proptype not in _PROPERTY_TYPES:
raise datastore_errors.BadValueError(
'Unsupported type for property %s: %s' % (name, proptype))
pbs = []
for v in values:
pb = entity_pb.Property()
pb.set_name(name.encode('utf-8'))
pb.set_multiple(multiple)
if _PROPERTY_MEANINGS.has_key(proptype):
pb.set_meaning(_PROPERTY_MEANINGS[proptype])
pbvalue = pb.mutable_value()
if v is None:
pass
elif isinstance(v, Blob):
pbvalue.set_stringvalue(v)
elif isinstance(v, (basestring, IM)):
if not isinstance(v, Text):
if isinstance(v, Link):
max_len = _MAX_LINK_PROPERTY_LENGTH
else:
