85 lines
2.9 KiB
Rust
85 lines
2.9 KiB
Rust
//! Helpers for extracting common labels from metrics before presenting them
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use std::{
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collections::BTreeMap,
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fmt::{Debug, Display},
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};
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/// A set of labels extracted by ExtractLabels
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pub type Labels = BTreeMap<String, String>;
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/// Common labels extracted from a very generic sequence of metric labels (key value pairs)
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pub struct ExtractLabels {
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/// The metric name (from __name__ label)
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pub name: String,
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/// Labels that are common to all metrics in the set
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pub common_labels: Labels,
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/// Labels specific to each metric (excluding common labels)
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pub specific_labels: Vec<Labels>,
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}
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impl ExtractLabels {
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/// Extract common and specific labels from an iterator of metric label sets.
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///
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/// Labels in `skip_labels` are excluded from both common and specific labels.
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pub fn new<'a, I, KV, K, V>(src: I, skip_labels: &[String]) -> Self
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where
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I: Iterator<Item = &'a KV>,
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KV: Clone + Debug + 'a,
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K: Display + 'a,
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V: Display + 'a,
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&'a KV: IntoIterator<Item = (&'a K, &'a V)>,
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{
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// Common labels needs to be String -> Option<String>, because when we find a conflict,
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// we need to poison that key (by putting None)
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let mut common_labels = BTreeMap::<String, Option<String>>::default();
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let mut specific_labels: Vec<Labels> = src
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.map(|kv| {
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let labels: Labels = kv
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.into_iter()
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.map(|(k, v)| {
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let k = k.to_string();
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let v = v.to_string();
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if let Some(existing_val) = common_labels.get_mut(&k) {
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// If the existing value is None, we already eliminated this label,
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// so don't add it back.
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if let Some(common_val) = existing_val
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&& common_val != &v
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{
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*existing_val = None;
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}
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} else {
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common_labels.insert(k.clone(), Some(v.clone()));
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}
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(k, v)
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})
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.collect();
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labels
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})
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.collect();
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let mut common_labels = common_labels
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.into_iter()
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.filter_map(|(k, maybe_v)| maybe_v.map(|v| (k, v)))
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.collect::<Labels>();
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for sl in skip_labels {
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common_labels.remove(sl);
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}
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for sp in &mut specific_labels {
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for sl in skip_labels {
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sp.remove(sl);
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}
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for cl in common_labels.keys() {
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sp.remove(cl);
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}
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}
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let name = common_labels.remove("__name__").unwrap_or_default();
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ExtractLabels {
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name,
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common_labels,
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specific_labels,
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}
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}
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}
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