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Signed-off-by: Palash Nigam <npalash25@gmail.com>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,151 @@ | ||
| //! Module implementing an Open Metrics histogram. | ||
| //! | ||
| //! See [`Summary`] for details. | ||
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| use super::{MetricType, TypedMetric}; | ||
| //use owning_ref::OwningRef; | ||
| //use std::iter::{self, once}; | ||
| use std::sync::{Arc, Mutex}; | ||
| use std::time::{Duration, Instant}; | ||
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| use quantiles::ckms::CKMS; | ||
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| /// Open Metrics [`Summary`] to measure distributions of discrete events. | ||
| #[derive(Debug)] | ||
| pub struct Summary { | ||
| target_quantile: Vec<f64>, | ||
| target_error: f64, | ||
| max_age_buckets: u64, | ||
| max_age_seconds: u64, | ||
| stream_duration: Duration, | ||
| inner: Arc<Mutex<InnerSummary>>, | ||
| } | ||
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| impl Clone for Summary { | ||
| fn clone(&self) -> Self { | ||
| Summary { | ||
| target_quantile: self.target_quantile.clone(), | ||
| target_error: self.target_error, | ||
| max_age_buckets: self.max_age_buckets, | ||
| max_age_seconds: self.max_age_seconds, | ||
| stream_duration: self.stream_duration, | ||
| inner: self.inner.clone(), | ||
| } | ||
| } | ||
| } | ||
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| #[derive(Debug)] | ||
| pub(crate) struct InnerSummary { | ||
| sum: f64, | ||
| count: u64, | ||
| quantile_streams: Vec<CKMS<f64>>, | ||
| // head_stream is like a cursor which carries the index | ||
| // of the stream in the quantile_streams that we want to query. | ||
| head_stream_idx: u64, | ||
| // timestamp at which the head_stream_idx was last rotated. | ||
| last_rotated_timestamp: Instant, | ||
| } | ||
|
|
||
| impl Summary { | ||
| /// Create a new [`Summary`]. | ||
| pub fn new(max_age_buckets: u64, max_age_seconds: u64, target_quantile: Vec<f64>, target_error: f64) -> Self { | ||
| let mut streams: Vec<CKMS<f64>> = Vec::new(); | ||
| for _ in 0..max_age_buckets { | ||
| streams.push(CKMS::new(target_error)); | ||
| } | ||
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|
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| let stream_duration = Duration::from_secs(max_age_seconds / max_age_buckets); | ||
| let last_rotated_timestamp = Instant::now(); | ||
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| if target_quantile.iter().any(|&x| x > 1.0 || x < 0.0) { | ||
| panic!("Quantile value out of range"); | ||
| } | ||
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| Summary{ | ||
| max_age_buckets, | ||
| max_age_seconds, | ||
| stream_duration, | ||
| target_quantile, | ||
| target_error, | ||
| inner: Arc::new(Mutex::new(InnerSummary { | ||
| sum: Default::default(), | ||
| count: Default::default(), | ||
| quantile_streams: streams, | ||
| head_stream_idx: 0, | ||
| last_rotated_timestamp, | ||
| })) | ||
| } | ||
| } | ||
|
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| /// Observe the given value. | ||
| pub fn observe(&self, v: f64) { | ||
| self.rotate_buckets(); | ||
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| let mut inner = self.inner.lock().unwrap(); | ||
| inner.sum += v; | ||
| inner.count += 1; | ||
|
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| // insert quantiles into all streams/buckets. | ||
| for stream in inner.quantile_streams.iter_mut() { | ||
| stream.insert(v); | ||
| } | ||
| } | ||
|
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| /// Retrieve the values of the summary metric. | ||
| pub fn get(&self) -> (f64, u64, Vec<(f64, f64)>) { | ||
| self.rotate_buckets(); | ||
|
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| let inner = self.inner.lock().unwrap(); | ||
| let sum = inner.sum; | ||
| let count = inner.count; | ||
| let mut quantile_values: Vec<(f64, f64)> = Vec::new(); | ||
|
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| for q in self.target_quantile.iter() { | ||
| match inner.quantile_streams[inner.head_stream_idx as usize].query(*q) { | ||
| Some((_, v)) => quantile_values.push((*q, v)), | ||
| None => continue, | ||
| }; | ||
| } | ||
| (sum, count, quantile_values) | ||
| } | ||
|
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| fn rotate_buckets(&self) { | ||
| let mut inner = self.inner.lock().unwrap(); | ||
| if inner.last_rotated_timestamp.elapsed() >= self.stream_duration { | ||
| inner.last_rotated_timestamp = Instant::now(); | ||
| if inner.head_stream_idx == self.max_age_buckets { | ||
| inner.head_stream_idx = 0; | ||
| } else { | ||
| inner.head_stream_idx += 1; | ||
| } | ||
| }; | ||
| } | ||
| } | ||
|
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| impl TypedMetric for Summary { | ||
| const TYPE: MetricType = MetricType::Summary; | ||
| } | ||
|
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| #[cfg(test)] | ||
| mod tests { | ||
| use super::*; | ||
|
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| #[test] | ||
| fn summary() { | ||
| let summary = Summary::new(5, 10, vec![0.5, 0.9, 0.99], 0.01); | ||
| summary.observe(1.0); | ||
| summary.observe(5.0); | ||
| summary.observe(10.0); | ||
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| let (s, c, q) = summary.get(); | ||
| assert_eq!(16.0, s); | ||
| assert_eq!(3, c); | ||
| assert_eq!(vec![(0.5, 5.0), (0.9, 10.0), (0.99, 10.0)], q); | ||
| } | ||
|
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| #[test] | ||
| #[should_panic(expected="Quantile value out of range")] | ||
| fn summary_panic() { | ||
| Summary::new(5, 10, vec![1.0, 5.0, 9.0], 0.01); | ||
| } | ||
| } |