#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# pytype: skip-file
from __future__ import absolute_import
import itertools
from array import array
from apache_beam.coders.coder_impl import StreamCoderImpl
from apache_beam.coders.coders import BytesCoder
from apache_beam.coders.coders import Coder
from apache_beam.coders.coders import FastCoder
from apache_beam.coders.coders import FloatCoder
from apache_beam.coders.coders import IterableCoder
from apache_beam.coders.coders import StrUtf8Coder
from apache_beam.coders.coders import TupleCoder
from apache_beam.coders.coders import VarIntCoder
from apache_beam.portability import common_urns
from apache_beam.portability.api import schema_pb2
from apache_beam.typehints.schemas import named_tuple_from_schema
from apache_beam.typehints.schemas import named_tuple_to_schema
__all__ = ["RowCoder"]
[docs]class RowCoder(FastCoder):
""" Coder for `typing.NamedTuple` instances.
Implements the beam:coder:row:v1 standard coder spec.
"""
def __init__(self, schema):
"""Initializes a :class:`RowCoder`.
Args:
schema (apache_beam.portability.api.schema_pb2.Schema): The protobuf
representation of the schema of the data that the RowCoder will be used
to encode/decode.
"""
self.schema = schema
self.components = [
RowCoder.coder_from_type(field.type) for field in self.schema.fields
]
def _create_impl(self):
return RowCoderImpl(self.schema, self.components)
[docs] def is_deterministic(self):
return all(c.is_deterministic() for c in self.components)
[docs] def to_type_hint(self):
return named_tuple_from_schema(self.schema)
[docs] def as_cloud_object(self, coders_context=None):
raise NotImplementedError("as_cloud_object not supported for RowCoder")
__hash__ = None # type: ignore[assignment]
def __eq__(self, other):
return type(self) == type(other) and self.schema == other.schema
[docs] def to_runner_api_parameter(self, unused_context):
return (common_urns.coders.ROW.urn, self.schema, [])
[docs] @Coder.register_urn(common_urns.coders.ROW.urn, schema_pb2.Schema)
def from_runner_api_parameter(payload, components, unused_context):
return RowCoder(payload)
[docs] @staticmethod
def from_type_hint(named_tuple_type, registry):
return RowCoder(named_tuple_to_schema(named_tuple_type))
[docs] @staticmethod
def coder_from_type(field_type):
type_info = field_type.WhichOneof("type_info")
if type_info == "atomic_type":
if field_type.atomic_type in (schema_pb2.INT32,
schema_pb2.INT64):
return VarIntCoder()
elif field_type.atomic_type == schema_pb2.DOUBLE:
return FloatCoder()
elif field_type.atomic_type == schema_pb2.STRING:
return StrUtf8Coder()
elif type_info == "array_type":
return IterableCoder(
RowCoder.coder_from_type(field_type.array_type.element_type))
# The Java SDK supports several more types, but the coders are not yet
# standard, and are not implemented in Python.
raise ValueError(
"Encountered a type that is not currently supported by RowCoder: %s" %
field_type)
class RowCoderImpl(StreamCoderImpl):
"""For internal use only; no backwards-compatibility guarantees."""
SIZE_CODER = VarIntCoder().get_impl()
NULL_MARKER_CODER = BytesCoder().get_impl()
def __init__(self, schema, components):
self.schema = schema
self.constructor = named_tuple_from_schema(schema)
self.components = list(c.get_impl() for c in components)
self.has_nullable_fields = any(
field.type.nullable for field in self.schema.fields)
def encode_to_stream(self, value, out, nested):
nvals = len(self.schema.fields)
self.SIZE_CODER.encode_to_stream(nvals, out, True)
attrs = [getattr(value, f.name) for f in self.schema.fields]
words = array('B')
if self.has_nullable_fields:
nulls = list(attr is None for attr in attrs)
if any(nulls):
words = array('B', itertools.repeat(0, (nvals+7)//8))
for i, is_null in enumerate(nulls):
words[i//8] |= is_null << (i % 8)
self.NULL_MARKER_CODER.encode_to_stream(words.tostring(), out, True)
for c, field, attr in zip(self.components, self.schema.fields, attrs):
if attr is None:
if not field.type.nullable:
raise ValueError(
"Attempted to encode null for non-nullable field \"{}\".".format(
field.name))
continue
c.encode_to_stream(attr, out, True)
def decode_from_stream(self, in_stream, nested):
nvals = self.SIZE_CODER.decode_from_stream(in_stream, True)
words = array('B')
words.fromstring(self.NULL_MARKER_CODER.decode_from_stream(in_stream, True))
if words:
nulls = ((words[i // 8] >> (i % 8)) & 0x01 for i in range(nvals))
else:
nulls = itertools.repeat(False, nvals)
# If this coder's schema has more attributes than the encoded value, then
# the schema must have changed. Populate the unencoded fields with nulls.
if len(self.components) > nvals:
nulls = itertools.chain(
nulls,
itertools.repeat(True, len(self.components) - nvals))
# Note that if this coder's schema has *fewer* attributes than the encoded
# value, we just need to ignore the additional values, which will occur
# here because we only decode as many values as we have coders for.
return self.constructor(*(
None if is_null else c.decode_from_stream(in_stream, True)
for c, is_null in zip(self.components, nulls)))
def _make_value_coder(self, nulls=itertools.repeat(False)):
components = [
component for component, is_null in zip(self.components, nulls)
if not is_null
] if self.has_nullable_fields else self.components
return TupleCoder(components).get_impl()