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Flag new heavy hitters: keys that enter the top-k #28

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111 changes: 111 additions & 0 deletions asap-precompute-rs/src/answers.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -301,10 +301,121 @@ impl DriftTracker {
}
}

/// The `(key, count)` of every `asap.topk` estimate in `answers`, by rank.
pub fn topk_of(answers: &[SketchEnvelope]) -> Vec<(String, f64)> {
let label = |e: &SketchEnvelope, k: &str| {
e.labels
.iter()
.find(|kv| kv.key == k)
.map(|kv| kv.value.clone())
};
let mut top: Vec<(u32, String, f64)> = answers
.iter()
.filter(|e| {
e.metric_name == "asap.topk" && label(e, "bound").as_deref() == Some("estimate")
})
.filter_map(|e| Some((label(e, "rank")?.parse().ok()?, label(e, "key")?, e.value)))
.collect();
top.sort_by_key(|t| t.0);
top.into_iter().map(|(_, k, v)| (k, v)).collect()
}

/// Flags heavy hitters that were not among the top keys of the previous
/// windows. Sketch and exact use the same rule.
#[derive(Default)]
pub struct NoveltyTracker {
/// Windows whose top keys form the baseline.
pub baseline_windows: usize,
history: HashMap<String, std::collections::VecDeque<HashSet<String>>>,
}

impl NoveltyTracker {
/// Tracker remembering `baseline_windows` windows.
pub fn new(baseline_windows: usize) -> Self {
Self {
baseline_windows,
history: HashMap::new(),
}
}

/// New heavy hitters in this window's `top` (key, count), as gauges and events.
pub fn observe(
&mut self,
template: &SketchEnvelope,
method: &str,
top: &[(String, f64)],
) -> (Vec<SketchEnvelope>, Vec<Event>) {
let key = format!("{}|{:?}", template.metric_name, template.labels);
let window = self.history.entry(key).or_default();
let (mut out, mut events) = (Vec::new(), Vec::new());
if window.len() >= 3 {
let attribute = template
.labels
.iter()
.find(|kv| kv.key == crate::matchers::ATTRIBUTE_KEY_LABEL)
.map(|kv| kv.value.clone())
.unwrap_or_default();
for (rank, (k, count)) in top.iter().enumerate() {
if window.iter().any(|seen| seen.contains(k)) {
continue;
}
out.push(gauge(
template,
"asap.topk.new",
method,
&[("key", k.clone())],
*count,
));
events.push(Event {
window_end_ms: template.window_end_ms,
method: method.into(),
kind: "novelty".into(),
attributes: vec![
KeyValue::new("attribute.key", attribute.clone()),
KeyValue::new("key", k.clone()),
KeyValue::new("rank", (rank + 1).to_string()),
KeyValue::new("count", format!("{count:.0}")),
],
body: format!(
"new heavy hitter {attribute}={k}: rank {} with {count:.0} points, absent from the top {} of the previous {} windows",
rank + 1,
top.len(),
window.len()
),
});
}
}
window.push_back(top.iter().map(|(k, _)| k.clone()).collect());
if window.len() > self.baseline_windows {
window.pop_front();
}
(out, events)
}
}

#[cfg(test)]
mod classifier_tests {
use super::*;

#[test]
fn novelty_after_three_windows() {
let mut t = NoveltyTracker::new(5);
let s = SketchEnvelope {
metric_name: "m".into(),
..Default::default()
};
let usual = vec![("a".to_string(), 10.0), ("b".to_string(), 5.0)];
for _ in 0..3 {
assert!(t.observe(&s, "sketch", &usual).1.is_empty());
}
let now = vec![("new".to_string(), 20.0), ("a".to_string(), 10.0)];
let (out, events) = t.observe(&s, "sketch", &now);
assert_eq!(out.len(), 1);
assert!(events[0].body.contains("new heavy hitter =new: rank 1"));
// The next window, the key is part of the baseline.
assert!(t.observe(&s, "sketch", &now).1.is_empty());
}

#[test]
fn ks_and_drift_events() {
let uniform = |x: f64| x.clamp(0.0, 1.0);
Expand Down
40 changes: 32 additions & 8 deletions asap-precompute-rs/src/otap/answer_nodes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -54,8 +54,8 @@ use otel_arrow_dfe_pdata::OtapPayload;

use super::codec::decode_pdata_to_observations;
use crate::answers::{
exact_answers, ks_distance, sketch_answers, CardinalityClassifier, CardinalityRules,
DriftRules, DriftTracker, Event, ExactWindow,
exact_answers, ks_distance, sketch_answers, topk_of, CardinalityClassifier, CardinalityRules,
DriftRules, DriftTracker, Event, ExactWindow, NoveltyTracker,
};
use crate::envelope::SketchEnvelope;
use crate::envelope::SketchType;
Expand Down Expand Up @@ -98,6 +98,13 @@ pub struct DetectorConfig {
/// Thresholds for distribution drift of quantile series.
#[serde(default)]
pub drift: DriftRules,
/// Windows whose top keys form the novelty baseline.
#[serde(default = "default_novelty_windows")]
pub novelty_windows: usize,
}

fn default_novelty_windows() -> usize {
10
}

/// `exact_answers` configuration.
Expand Down Expand Up @@ -128,6 +135,9 @@ pub struct ExactConfig {
/// Thresholds for distribution drift of quantile series.
#[serde(default)]
pub drift: DriftRules,
/// Windows whose top keys form the novelty baseline.
#[serde(default = "default_novelty_windows")]
pub novelty_windows: usize,
}

fn now_ms() -> u64 {
Expand Down Expand Up @@ -260,6 +270,7 @@ async fn observations(
struct SketchDetector {
config: DetectorConfig,
cardinality: CardinalityClassifier,
novelty: NoveltyTracker,
drift: DriftTracker,
/// Recent KLL windows per series, the drift baseline.
baselines: HashMap<String, VecDeque<KLLWrapper>>,
Expand Down Expand Up @@ -347,6 +358,12 @@ impl local::Processor<OtapPdata> for SketchDetector {
out.extend(gauges);
events.extend(event);
}
let top = topk_of(&answers);
if !top.is_empty() {
let (gauges, new) = self.novelty.observe(&env, "sketch", &top);
out.extend(gauges);
events.extend(new);
}
if let Some(d) = estimate_of(&answers, "asap.distinct") {
let (gauges, event) =
self.cardinality.observe(&env, "sketch", d, env.count);
Expand All @@ -371,6 +388,7 @@ struct ExactState {
struct ExactAnswers {
config: ExactConfig,
cardinality: CardinalityClassifier,
novelty: NoveltyTracker,
drift: DriftTracker,
/// Recent windows' sorted values per quantile series.
baselines: HashMap<String, VecDeque<Vec<f64>>>,
Expand Down Expand Up @@ -464,12 +482,15 @@ impl ExactAnswers {
out.extend(gauges);
events.extend(event);
}
out.extend(exact_answers(
&template,
&mut w,
&self.config.quantiles,
self.config.k,
));
let answers =
exact_answers(&template, &mut w, &self.config.quantiles, self.config.k);
let top = topk_of(&answers);
if !top.is_empty() {
let (gauges, new) = self.novelty.observe(&template, "exact", &top);
out.extend(gauges);
events.extend(new);
}
out.extend(answers);
if !w.values.is_empty() {
// exact_answers left the values sorted.
let (gauges, event) =
Expand Down Expand Up @@ -573,6 +594,7 @@ static SKETCH_DETECTOR: ProcessorFactory<OtapPdata> = ProcessorFactory {
Ok(ProcessorWrapper::local(
SketchDetector {
cardinality: CardinalityClassifier::new(config.cardinality.clone()),
novelty: NoveltyTracker::new(config.novelty_windows),
drift: DriftTracker::new(config.drift.clone()),
baselines: HashMap::new(),
config,
Expand Down Expand Up @@ -600,6 +622,7 @@ static EXACT_ANSWERS: ProcessorFactory<OtapPdata> = ProcessorFactory {
Ok(ProcessorWrapper::local(
ExactAnswers {
cardinality: CardinalityClassifier::new(config.cardinality.clone()),
novelty: NoveltyTracker::new(config.novelty_windows),
drift: DriftTracker::new(config.drift.clone()),
baselines: HashMap::new(),
config,
Expand Down Expand Up @@ -642,6 +665,7 @@ mod tests {
.unwrap();
let mut exact = ExactAnswers {
cardinality: CardinalityClassifier::new(config.cardinality.clone()),
novelty: NoveltyTracker::new(config.novelty_windows),
drift: DriftTracker::new(config.drift.clone()),
baselines: HashMap::new(),
config,
Expand Down
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