Source code for apache_beam.metrics.cells

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"""
This file contains metric cell classes. A metric cell is used to accumulate
in-memory changes to a metric. It represents a specific metric in a single
context.
"""

# pytype: skip-file

from __future__ import absolute_import
from __future__ import division

import threading
import time
from builtins import object
from typing import Optional

try:
  import cython
except ImportError:

  class fake_cython:
    compiled = False

  globals()['cython'] = fake_cython

__all__ = ['DistributionResult', 'GaugeResult']


class MetricCell(object):
  """For internal use only; no backwards-compatibility guarantees.

  Accumulates in-memory changes to a metric.

  A MetricCell represents a specific metric in a single context and bundle.
  All subclasses must be thread safe, as these are used in the pipeline runners,
  and may be subject to parallel/concurrent updates. Cells should only be used
  directly within a runner.
  """
  def __init__(self):
    self._lock = threading.Lock()

  def update(self, value):
    raise NotImplementedError

  def get_cumulative(self):
    raise NotImplementedError

  def __reduce__(self):
    raise NotImplementedError


class CounterCell(MetricCell):
  """For internal use only; no backwards-compatibility guarantees.

  Tracks the current value and delta of a counter metric.

  Each cell tracks the state of a metric independently per context per bundle.
  Therefore, each metric has a different cell in each bundle, cells are
  aggregated by the runner.

  This class is thread safe.
  """
  def __init__(self, *args):
    super(CounterCell, self).__init__(*args)
    self.value = CounterAggregator.identity_element()

  def reset(self):
    self.value = CounterAggregator.identity_element()

  def combine(self, other):
    # type: (CounterCell) -> CounterCell
    result = CounterCell()
    result.inc(self.value + other.value)
    return result

  def inc(self, n=1):
    self.update(n)

  def dec(self, n=1):
    self.update(-n)

  def update(self, value):
    if cython.compiled:
      ivalue = value
      # We hold the GIL, no need for another lock.
      self.value += ivalue
    else:
      with self._lock:
        self.value += value

  def get_cumulative(self):
    # type: () -> int
    with self._lock:
      return self.value

  def to_runner_api_monitoring_info(self, name, transform_id):
    from apache_beam.metrics import monitoring_infos
    return monitoring_infos.int64_user_counter(
        name.namespace,
        name.name,
        self.get_cumulative(),
        ptransform=transform_id)


class DistributionCell(MetricCell):
  """For internal use only; no backwards-compatibility guarantees.

  Tracks the current value and delta for a distribution metric.

  Each cell tracks the state of a metric independently per context per bundle.
  Therefore, each metric has a different cell in each bundle, that is later
  aggregated.

  This class is thread safe.
  """
  def __init__(self, *args):
    super(DistributionCell, self).__init__(*args)
    self.data = DistributionAggregator.identity_element()

  def reset(self):
    self.data = DistributionAggregator.identity_element()

  def combine(self, other):
    # type: (DistributionCell) -> DistributionCell
    result = DistributionCell()
    result.data = self.data.combine(other.data)
    return result

  def update(self, value):
    if cython.compiled:
      # We will hold the GIL throughout the entire _update.
      self._update(value)
    else:
      with self._lock:
        self._update(value)

  def _update(self, value):
    if cython.compiled:
      ivalue = value
    else:
      ivalue = int(value)
    self.data.count = self.data.count + 1
    self.data.sum = self.data.sum + ivalue
    if ivalue < self.data.min:
      self.data.min = ivalue
    if ivalue > self.data.max:
      self.data.max = ivalue

  def get_cumulative(self):
    # type: () -> DistributionData
    with self._lock:
      return self.data.get_cumulative()

  def to_runner_api_monitoring_info(self, name, transform_id):
    from apache_beam.metrics import monitoring_infos
    return monitoring_infos.int64_user_distribution(
        name.namespace,
        name.name,
        self.get_cumulative(),
        ptransform=transform_id)


class GaugeCell(MetricCell):
  """For internal use only; no backwards-compatibility guarantees.

  Tracks the current value and delta for a gauge metric.

  Each cell tracks the state of a metric independently per context per bundle.
  Therefore, each metric has a different cell in each bundle, that is later
  aggregated.

  This class is thread safe.
  """
  def __init__(self, *args):
    super(GaugeCell, self).__init__(*args)
    self.data = GaugeAggregator.identity_element()

  def reset(self):
    self.data = GaugeAggregator.identity_element()

  def combine(self, other):
    # type: (GaugeCell) -> GaugeCell
    result = GaugeCell()
    result.data = self.data.combine(other.data)
    return result

  def set(self, value):
    self.update(value)

  def update(self, value):
    value = int(value)
    with self._lock:
      # Set the value directly without checking timestamp, because
      # this value is naturally the latest value.
      self.data.value = value
      self.data.timestamp = time.time()

  def get_cumulative(self):
    # type: () -> GaugeData
    with self._lock:
      return self.data.get_cumulative()

  def to_runner_api_monitoring_info(self, name, transform_id):
    from apache_beam.metrics import monitoring_infos
    return monitoring_infos.int64_user_gauge(
        name.namespace,
        name.name,
        self.get_cumulative(),
        ptransform=transform_id)


[docs]class DistributionResult(object): """The result of a Distribution metric.""" def __init__(self, data): # type: (DistributionData) -> None self.data = data def __eq__(self, other): if isinstance(other, DistributionResult): return self.data == other.data else: return False def __hash__(self): return hash(self.data) def __ne__(self, other): # TODO(BEAM-5949): Needed for Python 2 compatibility. return not self == other def __repr__(self): return 'DistributionResult(sum={}, count={}, min={}, max={})'.format( self.sum, self.count, self.min, self.max) @property def max(self): return self.data.max if self.data.count else None @property def min(self): return self.data.min if self.data.count else None @property def count(self): return self.data.count @property def sum(self): return self.data.sum @property def mean(self): """Returns the float mean of the distribution. If the distribution contains no elements, it returns None. """ if self.data.count == 0: return None return self.data.sum / self.data.count
[docs]class GaugeResult(object): def __init__(self, data): # type: (GaugeData) -> None self.data = data def __eq__(self, other): if isinstance(other, GaugeResult): return self.data == other.data else: return False def __hash__(self): return hash(self.data) def __ne__(self, other): # TODO(BEAM-5949): Needed for Python 2 compatibility. return not self == other def __repr__(self): return '<GaugeResult(value={}, timestamp={})>'.format( self.value, self.timestamp) @property def value(self): return self.data.value @property def timestamp(self): return self.data.timestamp
class GaugeData(object): """For internal use only; no backwards-compatibility guarantees. The data structure that holds data about a gauge metric. Gauge metrics are restricted to integers only. This object is not thread safe, so it's not supposed to be modified by other than the GaugeCell that contains it. """ def __init__(self, value, timestamp=None): self.value = value self.timestamp = timestamp if timestamp is not None else 0 def __eq__(self, other): return self.value == other.value and self.timestamp == other.timestamp def __hash__(self): return hash((self.value, self.timestamp)) def __ne__(self, other): # TODO(BEAM-5949): Needed for Python 2 compatibility. return not self == other def __repr__(self): return '<GaugeData(value={}, timestamp={})>'.format( self.value, self.timestamp) def get_cumulative(self): # type: () -> GaugeData return GaugeData(self.value, timestamp=self.timestamp) def combine(self, other): # type: (Optional[GaugeData]) -> GaugeData if other is None: return self if other.timestamp > self.timestamp: return other else: return self @staticmethod def singleton(value, timestamp=None): # type: (...) -> GaugeData return GaugeData(value, timestamp=timestamp) class DistributionData(object): """For internal use only; no backwards-compatibility guarantees. The data structure that holds data about a distribution metric. Distribution metrics are restricted to distributions of integers only. This object is not thread safe, so it's not supposed to be modified by other than the DistributionCell that contains it. """ def __init__(self, sum, count, min, max): if count: self.sum = sum self.count = count self.min = min self.max = max else: self.sum = self.count = 0 self.min = 2**63 - 1 # Avoid Wimplicitly-unsigned-literal caused by -2**63. self.max = -self.min - 1 def __eq__(self, other): return ( self.sum == other.sum and self.count == other.count and self.min == other.min and self.max == other.max) def __hash__(self): return hash((self.sum, self.count, self.min, self.max)) def __ne__(self, other): # TODO(BEAM-5949): Needed for Python 2 compatibility. return not self == other def __repr__(self): return 'DistributionData(sum={}, count={}, min={}, max={})'.format( self.sum, self.count, self.min, self.max) def get_cumulative(self): # type: () -> DistributionData return DistributionData(self.sum, self.count, self.min, self.max) def combine(self, other): # type: (Optional[DistributionData]) -> DistributionData if other is None: return self return DistributionData( self.sum + other.sum, self.count + other.count, self.min if self.min < other.min else other.min, self.max if self.max > other.max else other.max) @staticmethod def singleton(value): return DistributionData(value, 1, value, value) class MetricAggregator(object): """For internal use only; no backwards-compatibility guarantees. Base interface for aggregating metric data during pipeline execution.""" def identity_element(self): """Returns the identical element of an Aggregation. For the identity element, it must hold that Aggregator.combine(any_element, identity_element) == any_element. """ raise NotImplementedError def combine(self, x, y): raise NotImplementedError def result(self, x): raise NotImplementedError class CounterAggregator(MetricAggregator): """For internal use only; no backwards-compatibility guarantees. Aggregator for Counter metric data during pipeline execution. Values aggregated should be ``int`` objects. """ @staticmethod def identity_element(): # type: () -> int return 0 def combine(self, x, y): # type: (...) -> int return int(x) + int(y) def result(self, x): # type: (...) -> int return int(x) class DistributionAggregator(MetricAggregator): """For internal use only; no backwards-compatibility guarantees. Aggregator for Distribution metric data during pipeline execution. Values aggregated should be ``DistributionData`` objects. """ @staticmethod def identity_element(): # type: () -> DistributionData return DistributionData(0, 0, 2**63 - 1, -2**63) def combine(self, x, y): # type: (DistributionData, DistributionData) -> DistributionData return x.combine(y) def result(self, x): # type: (DistributionData) -> DistributionResult return DistributionResult(x.get_cumulative()) class GaugeAggregator(MetricAggregator): """For internal use only; no backwards-compatibility guarantees. Aggregator for Gauge metric data during pipeline execution. Values aggregated should be ``GaugeData`` objects. """ @staticmethod def identity_element(): # type: () -> GaugeData return GaugeData(None, timestamp=0) def combine(self, x, y): # type: (GaugeData, GaugeData) -> GaugeData result = x.combine(y) return result def result(self, x): # type: (GaugeData) -> GaugeResult return GaugeResult(x.get_cumulative())