Source code for

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"""EvaluationContext tracks global state, triggers and watermarks."""

from __future__ import absolute_import

import collections
import threading

from apache_beam.transforms import sideinputs
from import Clock
from import WatermarkManager
from import TransformExecutor
from import DirectMetrics
from apache_beam.utils import counters

class _ExecutionContext(object):

  def __init__(self, watermarks, existing_state):
    self._watermarks = watermarks
    self._existing_state = existing_state

  def watermarks(self):
    return self._watermarks

  def existing_state(self):
    return self._existing_state

class _SideInputView(object):

  def __init__(self, view):
    self._view = view
    self.callable_queue = collections.deque()
    self.elements = []
    self.value = None
    self.has_result = False

class _SideInputsContainer(object):
  """An in-process container for side inputs.

  It provides methods for blocking until a side-input is available and writing
  to a side input.

  def __init__(self, views):
    self._lock = threading.Lock()
    self._views = {}
    for view in views:
      self._views[view] = _SideInputView(view)

  def get_value_or_schedule_after_output(self, side_input, task):
    with self._lock:
      view = self._views[side_input]
      if not view.has_result:
        task.blocked = True
      return (view.has_result, view.value)

  def add_values(self, side_input, values):
    with self._lock:
      view = self._views[side_input]
      assert not view.has_result

  def finalize_value_and_get_tasks(self, side_input):
    with self._lock:
      view = self._views[side_input]
      assert not view.has_result
      assert view.value is None
      assert view.callable_queue is not None
      view.value = self._pvalue_to_value(side_input, view.elements)
      view.elements = None
      result = tuple(view.callable_queue)
      for task in result:
        task.blocked = False
      view.callable_queue = None
      view.has_result = True
      return result

  def _pvalue_to_value(self, view, values):
    """Given a side input view, returns the associated value in requested form.

      view: SideInput for the requested side input.
      values: Iterable values associated with the side input.

      The side input in its requested form.

      ValueError: If values cannot be converted into the requested form.
    return sideinputs.SideInputMap(type(view), view._view_options(), values)

[docs]class EvaluationContext(object): """Evaluation context with the global state information of the pipeline. The evaluation context for a specific pipeline being executed by the DirectRunner. Contains state shared within the execution across all transforms. EvaluationContext contains shared state for an execution of the DirectRunner that can be used while evaluating a PTransform. This consists of views into underlying state and watermark implementations, access to read and write side inputs, and constructing counter sets and execution contexts. This includes executing callbacks asynchronously when state changes to the appropriate point (e.g. when a side input is requested and known to be empty). EvaluationContext also handles results by committing finalizing bundles based on the current global state and updating the global state appropriately. This includes updating the per-(step,key) state, updating global watermarks, and executing any callbacks that can be executed. """ def __init__(self, pipeline_options, bundle_factory, root_transforms, value_to_consumers, step_names, views): self.pipeline_options = pipeline_options self._bundle_factory = bundle_factory self._root_transforms = root_transforms self._value_to_consumers = value_to_consumers self._step_names = step_names self.views = views self._pcollection_to_views = collections.defaultdict(list) for view in views: self._pcollection_to_views[view.pvalue].append(view) # AppliedPTransform -> Evaluator specific state objects self._application_state_interals = {} self._watermark_manager = WatermarkManager( Clock(), root_transforms, value_to_consumers) self._side_inputs_container = _SideInputsContainer(views) self._pending_unblocked_tasks = [] self._counter_factory = counters.CounterFactory() self._cache = None self._metrics = DirectMetrics() self._lock = threading.Lock()
[docs] def use_pvalue_cache(self, cache): assert not self._cache self._cache = cache
[docs] def metrics(self): # TODO. Should this be made a @property? return self._metrics
@property def has_cache(self): return self._cache is not None
[docs] def append_to_cache(self, applied_ptransform, tag, elements): with self._lock: assert self._cache self._cache.append(applied_ptransform, tag, elements)
[docs] def is_root_transform(self, applied_ptransform): return applied_ptransform in self._root_transforms
[docs] def handle_result( self, completed_bundle, completed_timers, result): """Handle the provided result produced after evaluating the input bundle. Handle the provided TransformResult, produced after evaluating the provided committed bundle (potentially None, if the result of a root PTransform). The result is the output of running the transform contained in the TransformResult on the contents of the provided bundle. Args: completed_bundle: the bundle that was processed to produce the result. completed_timers: the timers that were delivered to produce the completed_bundle. result: the TransformResult of evaluating the input bundle Returns: the committed bundles contained within the handled result. """ with self._lock: committed_bundles = self._commit_bundles( result.uncommitted_output_bundles) self._watermark_manager.update_watermarks( completed_bundle, result.transform, completed_timers, committed_bundles, result.watermark_hold) self._metrics.commit_logical(completed_bundle, result.logical_metric_updates) # If the result is for a view, update side inputs container. if (result.uncommitted_output_bundles and result.uncommitted_output_bundles[0].pcollection in self._pcollection_to_views): for view in self._pcollection_to_views[ result.uncommitted_output_bundles[0].pcollection]: for committed_bundle in committed_bundles: # side_input must be materialized. self._side_inputs_container.add_values( view, committed_bundle.get_elements_iterable(make_copy=True)) if (self.get_execution_context(result.transform) .watermarks.input_watermark == WatermarkManager.WATERMARK_POS_INF): self._pending_unblocked_tasks.extend( self._side_inputs_container.finalize_value_and_get_tasks(view)) if result.counters: for counter in result.counters: merged_counter = self._counter_factory.get_counter(, counter.combine_fn) merged_counter.accumulator.merge([counter.accumulator]) self._application_state_interals[result.transform] = result.state return committed_bundles
[docs] def get_aggregator_values(self, aggregator_or_name): return self._counter_factory.get_aggregator_values(aggregator_or_name)
[docs] def schedule_pending_unblocked_tasks(self, executor_service): if self._pending_unblocked_tasks: with self._lock: for task in self._pending_unblocked_tasks: executor_service.submit(task) self._pending_unblocked_tasks = []
def _commit_bundles(self, uncommitted_bundles): """Commits bundles and returns a immutable set of committed bundles.""" for in_progress_bundle in uncommitted_bundles: producing_applied_ptransform = in_progress_bundle.pcollection.producer watermarks = self._watermark_manager.get_watermarks( producing_applied_ptransform) in_progress_bundle.commit(watermarks.synchronized_processing_output_time) return tuple(uncommitted_bundles)
[docs] def get_execution_context(self, applied_ptransform): return _ExecutionContext( self._watermark_manager.get_watermarks(applied_ptransform), self._application_state_interals.get(applied_ptransform))
[docs] def create_bundle(self, output_pcollection): """Create an uncommitted bundle for the specified PCollection.""" return self._bundle_factory.create_bundle(output_pcollection)
[docs] def create_empty_committed_bundle(self, output_pcollection): """Create empty bundle useful for triggering evaluation.""" return self._bundle_factory.create_empty_committed_bundle( output_pcollection)
[docs] def extract_fired_timers(self): return self._watermark_manager.extract_fired_timers()
[docs] def is_done(self, transform=None): """Checks completion of a step or the pipeline. Args: transform: AppliedPTransform to check for completion. Returns: True if the step will not produce additional output. If transform is None returns true if all steps are done. """ if transform: return self._is_transform_done(transform) for applied_ptransform in self._step_names: if not self._is_transform_done(applied_ptransform): return False return True
def _is_transform_done(self, transform): tw = self._watermark_manager.get_watermarks(transform) return tw.output_watermark == WatermarkManager.WATERMARK_POS_INF
[docs] def get_value_or_schedule_after_output(self, side_input, task): assert isinstance(task, TransformExecutor) return self._side_inputs_container.get_value_or_schedule_after_output( side_input, task)