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use std::collections::HashMap;
use std::time::SystemTime;
use metriken::{MetricEntry, Value};
use crate::snapshot::{Counter, Gauge, Histogram, Snapshot, SnapshotV1};
/// Produces a snapshot of metric readings.
pub struct Snapshotter {
filter: fn(&MetricEntry) -> bool,
metadata: HashMap<String, String>,
}
/// Used to build a new `Snapshotter`.
#[derive(Default)]
pub struct SnapshotterBuilder {
snapshotter: Snapshotter,
}
impl SnapshotterBuilder {
/// Construct a new builder. By default, all metric types are enabled and no
/// filtering is applied.
pub fn new() -> Self {
Self::default()
}
/// Consume the builder and return a `Snapshotter`.
pub fn build(self) -> Snapshotter {
self.snapshotter
}
/// Allow a user-supplied filtering function to be applied based on the
/// metric entry. The function must return true for any metric that should
/// be included in the snapshot.
pub fn filter(mut self, filter: fn(&MetricEntry) -> bool) -> Self {
self.snapshotter.filter = filter;
self
}
/// Add a key-value pair to the metadata.
pub fn metadata(mut self, key: String, value: String) -> Self {
self.snapshotter.metadata.insert(key, value);
self
}
}
impl Default for Snapshotter {
fn default() -> Self {
Self {
filter: |_| true,
metadata: HashMap::new(),
}
}
}
impl Snapshotter {
/// Produce a new snapshot.
pub fn snapshot(&self) -> Snapshot {
let ts = SystemTime::now();
let mut counters: Vec<Counter> = Vec::new();
let mut gauges: Vec<Gauge> = Vec::new();
let mut histograms: Vec<Histogram> = Vec::new();
// Iterate through metrics using numeric IDs as column names to avoid
// collisions between same-name metrics with different labels. The base
// metric name is stored in the "metric" metadata key for Tsdb/PromQL
// indexing.
for (metric_id, metric) in metriken::metrics().iter().enumerate() {
if !(self.filter)(metric) {
continue;
}
let column_name = format!("{metric_id}");
// Build metadata from user-defined labels + metric base name
let build_metadata = |metric: &MetricEntry| -> HashMap<String, String> {
let mut metadata = HashMap::from_iter(
metric
.metadata()
.into_iter()
.map(|(k, v)| (k.to_string(), v.to_string())),
);
metadata.insert("metric".to_string(), metric.name().replace('/', "_"));
if let Some(description) = metric.description().map(|v| v.to_string()) {
metadata.insert("description".to_string(), description);
}
metadata
};
match metric.value() {
Some(Value::Counter(value)) => {
counters.push(Counter {
name: column_name.clone(),
value,
metadata: build_metadata(metric),
});
}
Some(Value::Gauge(value)) => {
gauges.push(Gauge {
name: column_name.clone(),
value,
metadata: build_metadata(metric),
});
}
Some(Value::Histogram(h)) => {
if let Some(histogram) = h.load() {
let mut metadata = build_metadata(metric);
metadata.insert(
"grouping_power".to_string(),
histogram.config().grouping_power().to_string(),
);
metadata.insert(
"max_value_power".to_string(),
histogram.config().max_value_power().to_string(),
);
histograms.push(Histogram {
name: column_name.clone(),
value: histogram,
metadata,
});
}
}
Some(Value::CounterGroup(g)) => {
let base_metadata = build_metadata(metric);
for (idx, entry_meta) in g.metadata_snapshot() {
if let Some(value) = g.counter_value(idx) {
let mut metadata = base_metadata.clone();
metadata.extend(entry_meta);
counters.push(Counter {
name: format!("{column_name}x{idx}"),
value,
metadata,
});
}
}
}
Some(Value::GaugeGroup(g)) => {
let base_metadata = build_metadata(metric);
for (idx, entry_meta) in g.metadata_snapshot() {
if let Some(value) = g.gauge_value(idx) {
let mut metadata = base_metadata.clone();
metadata.extend(entry_meta);
gauges.push(Gauge {
name: format!("{column_name}x{idx}"),
value,
metadata,
});
}
}
}
Some(Value::HistogramGroup(g)) => {
let base_metadata = build_metadata(metric);
for (idx, entry_meta) in g.metadata_snapshot() {
if let Some(histogram) = g.load_histogram(idx) {
let mut metadata = base_metadata.clone();
metadata.extend(entry_meta);
metadata.insert(
"grouping_power".to_string(),
histogram.config().grouping_power().to_string(),
);
metadata.insert(
"max_value_power".to_string(),
histogram.config().max_value_power().to_string(),
);
histograms.push(Histogram {
name: format!("{column_name}x{idx}"),
value: histogram,
metadata,
});
}
}
}
_ => continue,
}
}
Snapshot::V1(SnapshotV1 {
systemtime: ts,
metadata: self.metadata.clone(),
counters,
gauges,
histograms,
})
}
}