rohdesamuel commented on a change in pull request #10497: [BEAM-8335] Add the ReverseTestStream URL: https://github.com/apache/beam/pull/10497#discussion_r386693162
########## File path: sdks/python/apache_beam/testing/test_stream.py ########## @@ -314,3 +355,239 @@ def from_runner_api_parameter(ptransform, payload, context): coder=coder, events=[Event.from_runner_api(e, coder) for e in payload.events], output_tags=output_tags) + + +class TimingInfo(object): + def __init__(self, processing_time, watermark): + self._processing_time = timestamp.Timestamp.of(processing_time) + self._watermark = timestamp.Timestamp.of(watermark) + + @property + def processing_time(self): + return self._processing_time + + @property + def watermark(self): + return self._watermark + + def __repr__(self): + return '({}, {}, {})'.format( + self.event_timestamp, self.processing_time, self.watermark) + + +class PairWithTiming(PTransform): + """Pairs the input element with timing information. + + Input: element; output: KV(element, timing information) + Where timing information := (processing time, watermark) + + This is used in the ReverseTestStream implementation to replay watermark + advancements. + """ + + URN = "beam:transform:pair_with_timing:v1" + + def expand(self, pcoll): + return pvalue.PCollection.from_(pcoll) + + +class ReverseTestStream(PTransform): + """A Transform that can create TestStream events from a stream of elements. + + This currently assumes that this the pipeline being run on a single machine + and elements come in order and are outputted in the same order that they came + in. + """ + class Format(Enum): + TEST_STREAM_EVENTS = 1 + TEST_STREAM_FILE_RECORDS = 2 + SERIALIZED_TEST_STREAM_FILE_RECORDS = 3 + + def __init__( + self, sample_resolution_sec, output_tag, coder=None, output_format=None): + self._sample_resolution_sec = sample_resolution_sec + self._output_tag = output_tag + self._output_format = output_format if output_format \ + else ReverseTestStream.Format.TEST_STREAM_EVENTS + self._coder = coder if coder else beam.coders.FastPrimitivesCoder() + + def expand(self, pcoll): + generator = ( + _TestStreamFileRecordGenerator(coder=self._coder) if ( + self._output_format in ( + self.Format.TEST_STREAM_FILE_RECORDS, + self.Format.SERIALIZED_TEST_STREAM_FILE_RECORDS)) else + _TestStreamEventGenerator()) + + ret = ( + pcoll + | beam.WindowInto(beam.window.GlobalWindows()) + + # First get the initial timing information. This will be used to start + # the periodic timers which will generate processing time and watermark + # advancements every `sample_resolution_sec`. + | 'initial timing' >> PairWithTiming() + + # Next, map every element to the same key so that only a single timer is + # started for this given ReverseTestStream. + | beam.Map(lambda x: (0, x)) + + # Next, pass-through each element which will be paired with its timing + # info in the next step. Also, start the periodic timers. We use timers + # in this situation to capture watermark advancements that occur when + # there are no elements being produced upstream. + | beam.ParDo( + _WatermarkEventGenerator( + output_tag=self._output_tag, + sample_resolution_sec=self._sample_resolution_sec)) + + # Next, retrieve the timing information for watermark events that were + # generated in the previous step. This is because elements generated + # through the timers don't have their timing information yet. + | 'timing info for watermarks' >> PairWithTiming() + + # Format the events properly. + | beam.ParDo(generator)) + + if self._output_format == self.Format.SERIALIZED_TEST_STREAM_FILE_RECORDS: + + def serializer(e): + return e.SerializeToString() + + ret = ret | 'serializer' >> beam.Map(serializer) + + return ret + + +class _WatermarkEventGenerator(beam.DoFn): + # Used to return the initial timing information. + EXECUTE_ONCE_STATE = beam.transforms.userstate.BagStateSpec( + name='execute_once_state', coder=beam.coders.FastPrimitivesCoder()) + WATERMARK_TRACKER = TimerSpec('watermark_tracker', TimeDomain.REAL_TIME) + + def __init__(self, output_tag, sample_resolution_sec=0.1): + self._output_tag = output_tag + self._sample_resolution_sec = sample_resolution_sec + + @on_timer(WATERMARK_TRACKER) + def on_watermark_tracker( + self, + timestamp=beam.DoFn.TimestampParam, + window=beam.DoFn.WindowParam, + watermark_tracker=beam.DoFn.TimerParam(WATERMARK_TRACKER)): + next_sample_time = (timestamp.micros * 1e-6) + self._sample_resolution_sec + watermark_tracker.set(next_sample_time) + + # Generate two events, the delta since the last sample and a place-holder + # WatermarkEvent. This is a placeholder because we can't otherwise add the + # watermark from the runner to the event. + yield ProcessingTimeEvent(self._sample_resolution_sec) + yield WatermarkEvent(MIN_TIMESTAMP) + + def process( + self, + e, + timestamp=beam.DoFn.TimestampParam, + window=beam.DoFn.WindowParam, + watermark_tracker=beam.DoFn.TimerParam(WATERMARK_TRACKER), + execute_once_state=beam.DoFn.StateParam(EXECUTE_ONCE_STATE)): + + _, (element, timing_info) = e + + first_time = next(execute_once_state.read(), True) + if first_time: + # Generate the initial timing events. + execute_once_state.add(False) + now_sec = timing_info.processing_time.micros * 1e-6 + watermark_tracker.set(now_sec + self._sample_resolution_sec) + + # Here we capture the initial time offset and initial watermark. This is + # where we emit the TestStreamFileHeader. + yield TestStreamFileHeader(tag=self._output_tag) + yield ProcessingTimeEvent( + Duration(micros=timing_info.processing_time.micros)) + yield WatermarkEvent(MIN_TIMESTAMP) + yield element + + +class _TestStreamEventGenerator(beam.DoFn): + def start_bundle(self): + self.elements = [] + self.timing_events = [] + + def finish_bundle(self): + if self.timing_events: + yield WindowedValue( + self.timing_events, timestamp=0, windows=[beam.window.GlobalWindow()]) + + if self.elements: + yield WindowedValue([ElementEvent(self.elements)], + timestamp=0, + windows=[beam.window.GlobalWindow()]) + + def process(self, e, timestamp=beam.DoFn.TimestampParam): + element, timing_info = e + if isinstance(element, WatermarkEvent): + element.new_watermark = timing_info.watermark.micros Review comment: Done ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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