Class: OpenTelemetry::SDK::Metrics::Aggregation::ExponentialBucketHistogram

Inherits:
Object
  • Object
show all
Defined in:
lib/opentelemetry/sdk/metrics/aggregation/exponential_bucket_histogram.rb

Overview

Contains the implementation of the ExponentialBucketHistogram aggregation

Constant Summary collapse

MAX_SCALE =

relate to min max scale: opentelemetry.io/docs/specs/otel/metrics/sdk/#support-a-minimum-and-maximum-scale

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MIN_SCALE = 
-10
MAX_SIZE = 
160

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(aggregation_temporality: ENV.fetch('OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE', :delta), max_size: MAX_SIZE, max_scale: MAX_SCALE, record_min_max: true, zero_threshold: 0) ⇒ ExponentialBucketHistogram

The default boundaries are calculated based on default max_size and max_scale values



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# File 'lib/opentelemetry/sdk/metrics/aggregation/exponential_bucket_histogram.rb', line 27

def initialize(
  aggregation_temporality: ENV.fetch('OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE', :delta),
  max_size: MAX_SIZE,
  max_scale: MAX_SCALE,
  record_min_max: true,
  zero_threshold: 0
)
  @aggregation_temporality = aggregation_temporality
  @record_min_max = record_min_max
  @min            = Float::INFINITY
  @max            = -Float::INFINITY
  @sum            = 0
  @count          = 0
  @zero_threshold = zero_threshold
  @zero_count     = 0
  @size           = validate_size(max_size)
  @scale          = validate_scale(max_scale)

  @mapping = new_mapping(@scale)
end

Instance Attribute Details

#aggregation_temporality ⇒ Object (readonly)

rubocop:disable Metrics/ClassLength



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# File 'lib/opentelemetry/sdk/metrics/aggregation/exponential_bucket_histogram.rb', line 19

def aggregation_temporality
  @aggregation_temporality
end

Instance Method Details

#collect(start_time, end_time, data_points) ⇒ Object 



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# File 'lib/opentelemetry/sdk/metrics/aggregation/exponential_bucket_histogram.rb', line 48

def collect(start_time, end_time, data_points)
  if @aggregation_temporality == :delta
    # Set timestamps and 'move' data point values to result.
    hdps = data_points.values.map! do |hdp|
      hdp.start_time_unix_nano = start_time
      hdp.time_unix_nano = end_time
      hdp
    end
    data_points.clear
    hdps
  else
    # Update timestamps and take a snapshot.
    data_points.values.map! do |hdp|
      hdp.start_time_unix_nano ||= start_time # Start time of a data point is from the first observation.
      hdp.time_unix_nano = end_time
      hdp = hdp.dup
      hdp.positive = hdp.positive.dup
      hdp.negative = hdp.negative.dup
      hdp
    end
  end
end

#update(amount, attributes, data_points) ⇒ Object

rubocop:disable Metrics/MethodLength



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# File 'lib/opentelemetry/sdk/metrics/aggregation/exponential_bucket_histogram.rb', line 72

def update(amount, attributes, data_points)
  # fetch or initialize the ExponentialHistogramDataPoint
  hdp = data_points.fetch(attributes) do
    if @record_min_max
      min = Float::INFINITY
      max = -Float::INFINITY
    end

    data_points[attributes] = ExponentialHistogramDataPoint.new(
      attributes,
      nil,                                                               # :start_time_unix_nano
      0,                                                                 # :time_unix_nano
      0,                                                                 # :count
      0,                                                                 # :sum
      @scale,                                                            # :scale
      @zero_count,                                                       # :zero_count
      ExponentialHistogram::Buckets.new,  # :positive
      ExponentialHistogram::Buckets.new,  # :negative
      0,                                                                 # :flags
      nil,                                                               # :exemplars
      min,                                                               # :min
      max,                                                               # :max
      @zero_threshold # :zero_threshold)
    )
  end

  # Start to populate the data point (esp. the buckets)
  if @record_min_max
    hdp.max = amount if amount > hdp.max
    hdp.min = amount if amount < hdp.min
  end

  hdp.sum += amount
  hdp.count += 1

  if amount.abs <= @zero_threshold
    hdp.zero_count += 1
    hdp.scale = 0 if hdp.count == hdp.zero_count # if always getting zero, then there is no point to keep doing the update
    return
  end

  # rescale, map to index, update the buckets here
  buckets = amount.positive? ? hdp.positive : hdp.negative
  amount = -amount if amount.negative?

  bucket_index = @mapping.map_to_index(amount)

  rescaling_needed = false
  low = high = 0

  if buckets.counts == [0] # special case of empty
    buckets.index_start = bucket_index
    buckets.index_end   = bucket_index
    buckets.index_base  = bucket_index

  elsif bucket_index < buckets.index_start && (buckets.index_end - bucket_index) >= @size
    rescaling_needed = true
    low = bucket_index
    high = buckets.index_end

  elsif bucket_index > buckets.index_end && (bucket_index - buckets.index_start) >= @size
    rescaling_needed = true
    low = buckets.index_start
    high = bucket_index
  end

  if rescaling_needed
    scale_change = get_scale_change(low, high)
    downscale(scale_change, hdp.positive, hdp.negative)
    new_scale = @mapping.scale - scale_change
    hdp.scale = new_scale
    @mapping = new_mapping(new_scale)
    bucket_index = @mapping.map_to_index(amount)

    OpenTelemetry.logger.debug "Rescaled with new scale #{new_scale} from #{low} and #{high}; bucket_index is updated to #{bucket_index}"
  end

  # adjust buckets based on the bucket_index
  if bucket_index < buckets.index_start
    span = buckets.index_end - bucket_index
    grow_buckets(span, buckets)
    buckets.index_start = bucket_index
  elsif bucket_index > buckets.index_end
    span = bucket_index - buckets.index_start
    grow_buckets(span, buckets)
    buckets.index_end = bucket_index
  end

  bucket_index -= buckets.index_base
  bucket_index += buckets.counts.size if bucket_index.negative?

  buckets.increment_bucket(bucket_index)
  nil
end