Struct ExponentialHistogram

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pub struct ExponentialHistogram { /* private fields */ }

Expand description

An auto-scaling histogram approximation implementation following the opentelemetry exponential histogram algorithm.

Implementations§

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impl ExponentialHistogram

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pub fn new(desired_scale: u8) -> Self

Desired scale will drop as necessary to match the static max buckets configuration. This will happen dynamically in response to observed range. If your distribution range falls within 160 contiguous buckets somewhere the desired scale’s range, then your output scale will match your desired scale. If your observed range exceeds 160 buckets then scale will be reduced to reflect the data’s width.

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pub fn new_with_max_buckets(desired_scale: u8, max_buckets: u16) -> Self

Desired scale will drop as necessary to match the static max buckets configuration. This will happen dynamically in response to observed range. If your distribution range falls within max_buckets contiguous buckets somewhere the desired scale’s range, then your output scale will match your desired scale. If your observed range exceeds max_buckets then scale will be reduced to reflect the data’s width.

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pub fn reset(&mut self)

Reset this histogram to an empty state

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pub fn accumulate<T: Into<f64>>(&mut self, value: T)

Observe a value, increasing its bucket’s count by 1

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pub fn is_empty(&self) -> bool

True when there aren’t any measurements in this histogram

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pub fn count(&self) -> usize

How many observations have been made?

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pub fn sum(&self) -> f64

This is an approximation, just using the positive buckets for the sum.

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pub fn min(&self) -> f64

This is an approximation, just using the positive buckets for the min.

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pub fn max(&self) -> f64

This is an approximation, just using the positive buckets for the max.

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pub fn scale(&self) -> u8

What is the current scale (as defined by opentelemetry exponential histogram)?

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pub fn bucket_start_offset(&self) -> usize

What is the current bucket start offset (as defined by opentelemetry exponential histogram)?

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pub fn take_counts(self) -> (VecDeque<usize>, VecDeque<usize>)

Remove and return (positive, negative) bucket counts per the opentelemetry histogram concept.

Remember that index 0 is actually the bucket_start_offset()’th bucket (as defined by opentelemetry exponential histogram).

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pub fn has_negatives(&self) -> bool

Are there any negative observations?

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pub fn value_counts(&self) -> impl Iterator<Item = (f64, usize)> + '_

Iterate pairs of bucket->count. The bucket thresholds are defined by the opentelemetry exponential histogram format. You do not need to do any extra math, this walks the actual mapping of bucket-to-count.