Source code for apache_beam.testing.test_stream

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"""Provides TestStream for verifying streaming runner semantics.

For internal use only; no backwards-compatibility guarantees.

from abc import ABCMeta
from abc import abstractmethod

from apache_beam import coders
from apache_beam import pvalue
from apache_beam.transforms import PTransform
from apache_beam.transforms.window import TimestampedValue
from apache_beam.utils import timestamp
from apache_beam.utils.windowed_value import WindowedValue

__all__ = [

[docs]class Event(object): """Test stream event to be emitted during execution of a TestStream.""" __metaclass__ = ABCMeta def __cmp__(self, other): if type(self) is not type(other): return cmp(type(self), type(other)) return self._typed_cmp(other) @abstractmethod def _typed_cmp(self, other): raise NotImplementedError
[docs]class ElementEvent(Event): """Element-producing test stream event.""" def __init__(self, timestamped_values): self.timestamped_values = timestamped_values def _typed_cmp(self, other): return cmp(self.timestamped_values, other.timestamped_values)
[docs]class WatermarkEvent(Event): """Watermark-advancing test stream event.""" def __init__(self, new_watermark): self.new_watermark = timestamp.Timestamp.of(new_watermark) def _typed_cmp(self, other): return cmp(self.new_watermark, other.new_watermark)
[docs]class ProcessingTimeEvent(Event): """Processing time-advancing test stream event.""" def __init__(self, advance_by): self.advance_by = timestamp.Duration.of(advance_by) def _typed_cmp(self, other): return cmp(self.advance_by, other.advance_by)
[docs]class TestStream(PTransform): """Test stream that generates events on an unbounded PCollection of elements. Each event emits elements, advances the watermark or advances the processing time. After all of the specified elements are emitted, ceases to produce output. """ def __init__(self, coder=coders.FastPrimitivesCoder): assert coder is not None self.coder = coder self.current_watermark = timestamp.MIN_TIMESTAMP = []
[docs] def expand(self, pbegin): assert isinstance(pbegin, pvalue.PBegin) self.pipeline = pbegin.pipeline return pvalue.PCollection(self.pipeline)
def _infer_output_coder(self, input_type=None, input_coder=None): return self.coder def _add(self, event): if isinstance(event, ElementEvent): for tv in event.timestamped_values: assert tv.timestamp < timestamp.MAX_TIMESTAMP, ( 'Element timestamp must be before timestamp.MAX_TIMESTAMP.') elif isinstance(event, WatermarkEvent): assert event.new_watermark > self.current_watermark, ( 'Watermark must strictly-monotonically advance.') self.current_watermark = event.new_watermark elif isinstance(event, ProcessingTimeEvent): assert event.advance_by > 0, ( 'Must advance processing time by positive amount.') else: raise ValueError('Unknown event: %s' % event)
[docs] def add_elements(self, elements): """Add elements to the TestStream. Elements added to the TestStream will be produced during pipeline execution. These elements can be TimestampedValue, WindowedValue or raw unwrapped elements that are serializable using the TestStream's specified Coder. When a TimestampedValue or a WindowedValue element is used, the timestamp of the TimestampedValue or WindowedValue will be the timestamp of the produced element; otherwise, the current watermark timestamp will be used for that element. The windows of a given WindowedValue are ignored by the TestStream. """ timestamped_values = [] for element in elements: if isinstance(element, TimestampedValue): timestamped_values.append(element) elif isinstance(element, WindowedValue): # Drop windows for elements in test stream. timestamped_values.append( TimestampedValue(element.value, element.timestamp)) else: # Add elements with timestamp equal to current watermark. timestamped_values.append( TimestampedValue(element, self.current_watermark)) self._add(ElementEvent(timestamped_values)) return self
[docs] def advance_watermark_to(self, new_watermark): """Advance the watermark to a given Unix timestamp. The Unix timestamp value used must be later than the previous watermark value and should be given as an int, float or utils.timestamp.Timestamp object. """ self._add(WatermarkEvent(new_watermark)) return self
[docs] def advance_watermark_to_infinity(self): """Advance the watermark to the end of time.""" self.advance_watermark_to(timestamp.MAX_TIMESTAMP) return self
[docs] def advance_processing_time(self, advance_by): """Advance the current processing time by a given duration in seconds. The duration must be a positive second duration and should be given as an int, float or utils.timestamp.Duration object. """ self._add(ProcessingTimeEvent(advance_by)) return self