Source code for apache_beam.utils.urns

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"""For internal use only; no backwards-compatibility guarantees."""

import abc
import inspect

from google.protobuf import wrappers_pb2

from apache_beam.internal import pickler
from apache_beam.utils import proto_utils

PICKLED_WINDOW_FN = "beam:windowfn:pickled_python:v0.1"
GLOBAL_WINDOWS_FN = "beam:windowfn:global_windows:v0.1"
FIXED_WINDOWS_FN = "beam:windowfn:fixed_windows:v0.1"
SLIDING_WINDOWS_FN = "beam:windowfn:sliding_windows:v0.1"
SESSION_WINDOWS_FN = "beam:windowfn:session_windows:v0.1"

PICKLED_DO_FN = "beam:dofn:pickled_python:v0.1"
PICKLED_DO_FN_INFO = "beam:dofn:pickled_python_info:v0.1"
PICKLED_COMBINE_FN = "beam:combinefn:pickled_python:v0.1"

PICKLED_TRANSFORM = "beam:ptransform:pickled_python:v0.1"
PARDO_TRANSFORM = "beam:ptransform:pardo:v0.1"
GROUP_BY_KEY_TRANSFORM = "beam:ptransform:group_by_key:v0.1"
GROUP_BY_KEY_ONLY_TRANSFORM = "beam:ptransform:group_by_key_only:v0.1"
GROUP_ALSO_BY_WINDOW_TRANSFORM = "beam:ptransform:group_also_by_window:v0.1"
COMBINE_PER_KEY_TRANSFORM = "beam:ptransform:combine_per_key:v0.1"
COMBINE_GROUPED_VALUES_TRANSFORM = "beam:ptransform:combine_grouped_values:v0.1"
FLATTEN_TRANSFORM = "beam:ptransform:flatten:v0.1"
READ_TRANSFORM = "beam:ptransform:read:v0.1"
WINDOW_INTO_TRANSFORM = "beam:ptransform:window_into:v0.1"

PICKLED_SOURCE = "beam:source:pickled_python:v0.1"

PICKLED_CODER = "beam:coder:pickled_python:v0.1"
BYTES_CODER = "urn:beam:coders:bytes:0.1"
VAR_INT_CODER = "urn:beam:coders:varint:0.1"
INTERVAL_WINDOW_CODER = "urn:beam:coders:interval_window:0.1"
ITERABLE_CODER = "urn:beam:coders:stream:0.1"
KV_CODER = "urn:beam:coders:kv:0.1"
LENGTH_PREFIX_CODER = "urn:beam:coders:length_prefix:0.1"
GLOBAL_WINDOW_CODER = "urn:beam:coders:urn:beam:coders:global_window:0.1"
WINDOWED_VALUE_CODER = "urn:beam:coders:windowed_value:0.1"

[docs]class RunnerApiFn(object): """Abstract base class that provides urn registration utilities. A class that inherits from this class will get a registration-based from_runner_api and to_runner_api method that convert to and from beam_runner_api_pb2.SdkFunctionSpec. Additionally, register_pickle_urn can be called from the body of a class to register serialization via pickling. """ # TODO(BEAM-2685): Issue with dill + local classes + abc metaclass # __metaclass__ = abc.ABCMeta _known_urns = {} @abc.abstractmethod
[docs] def to_runner_api_parameter(self, unused_context): """Returns the urn and payload for this Fn. The returned urn(s) should be registered with `register_urn`. """ pass
[docs] def register_urn(cls, urn, parameter_type, fn=None): """Registeres a urn with a constructor. For example, if 'beam:fn:foo' had paramter type FooPayload, one could write `RunnerApiFn.register_urn('bean:fn:foo', FooPayload, foo_from_proto)` where foo_from_proto took as arguments a FooPayload and a PipelineContext. This function can also be used as a decorator rather than passing the callable in as the final parameter. A corresponding to_runner_api_parameter method would be expected that returns the tuple ('beam:fn:foo', FooPayload) """ def register(fn): cls._known_urns[urn] = parameter_type, fn return staticmethod(fn) if fn: # Used as a statement. register(fn) else: # Used as a decorator. return register
[docs] def register_pickle_urn(cls, pickle_urn): """Registers and implements the given urn via pickling. """ inspect.currentframe().f_back.f_locals['to_runner_api_parameter'] = ( lambda self, context: ( pickle_urn, wrappers_pb2.BytesValue(value=pickler.dumps(self)))) cls.register_urn( pickle_urn, wrappers_pb2.BytesValue, lambda proto, unused_context: pickler.loads(proto.value))
[docs] def to_runner_api(self, context): """Returns an SdkFunctionSpec encoding this Fn. Prefer overriding self.to_runner_api_parameter. """ from apache_beam.portability.api import beam_runner_api_pb2 urn, typed_param = self.to_runner_api_parameter(context) return beam_runner_api_pb2.SdkFunctionSpec( spec=beam_runner_api_pb2.FunctionSpec( urn=urn, payload=typed_param.SerializeToString() if typed_param is not None else None))
[docs] def from_runner_api(cls, fn_proto, context): """Converts from an SdkFunctionSpec to a Fn object. Prefer registering a urn with its parameter type and constructor. """ parameter_type, constructor = cls._known_urns[fn_proto.spec.urn] return constructor( proto_utils.parse_Bytes(fn_proto.spec.payload, parameter_type), context)