Source code for apache_beam.runners.pipeline_context

# 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
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.

"""Utility class for serializing pipelines via the runner API.

For internal use only; no backwards-compatibility guarantees.

from apache_beam import pipeline
from apache_beam import pvalue
from apache_beam import coders
from apache_beam.runners.api import beam_runner_api_pb2
from apache_beam.transforms import core

class _PipelineContextMap(object):
  """This is a bi-directional map between objects and ids.

  Under the hood it encodes and decodes these objects into runner API
  def __init__(self, context, obj_type, proto_map=None):
    self._pipeline_context = context
    self._obj_type = obj_type
    self._obj_to_id = {}
    self._id_to_obj = {}
    self._id_to_proto = proto_map if proto_map else {}
    self._counter = 0

  def _unique_ref(self):
    self._counter += 1
    return "ref_%s_%s" % (self._obj_type.__name__, self._counter)

  def populate_map(self, proto_map):
    for id, proto in self._id_to_proto.items():

  def get_id(self, obj):
    if obj not in self._obj_to_id:
      id = self._unique_ref()
      self._id_to_obj[id] = obj
      self._obj_to_id[obj] = id
      self._id_to_proto[id] = obj.to_runner_api(self._pipeline_context)
    return self._obj_to_id[obj]

  def get_by_id(self, id):
    if id not in self._id_to_obj:
      self._id_to_obj[id] = self._obj_type.from_runner_api(
          self._id_to_proto[id], self._pipeline_context)
    return self._id_to_obj[id]

[docs]class PipelineContext(object): """For internal use only; no backwards-compatibility guarantees. Used for accessing and constructing the referenced objects of a Pipeline. """ _COMPONENT_TYPES = { 'transforms': pipeline.AppliedPTransform, 'pcollections': pvalue.PCollection, 'coders': coders.Coder, 'windowing_strategies': core.Windowing, # TODO: environment } def __init__(self, context_proto=None): for name, cls in self._COMPONENT_TYPES.items(): setattr( self, name, _PipelineContextMap( self, cls, getattr(context_proto, name, None))) @staticmethod
[docs] def from_runner_api(proto): return PipelineContext(proto)
[docs] def to_runner_api(self): context_proto = beam_runner_api_pb2.Components() for name in self._COMPONENT_TYPES: getattr(self, name).populate_map(getattr(context_proto, name)) return context_proto