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use std::collections::HashMap;
use metriken::{AtomicHistogram, MetricEntry, RwLockHistogram, Value};
use crate::snapshot::{Counter, Gauge, Histogram};
use crate::Snapshot;
/// 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 mut snapshot = Snapshot::new();
snapshot.metadata = self.metadata.clone();
// iterate through the metrics and build-up the snapshot
for metric in &metriken::metrics() {
if !(self.filter)(metric) {
continue;
}
match metric.value() {
Some(Value::Counter(value)) => {
let mut counter = Counter {
name: metric.formatted(metriken::Format::Simple),
value,
metadata: HashMap::from_iter(
metric
.metadata()
.into_iter()
.map(|(k, v)| (k.to_string(), v.to_string())),
),
};
if let Some(description) = metric.description().map(|v| v.to_string()) {
counter
.metadata
.insert("description".to_string(), description);
}
snapshot.counters.push(counter);
}
Some(Value::Gauge(value)) => {
let mut gauge = Gauge {
name: metric.formatted(metriken::Format::Simple),
value,
metadata: HashMap::from_iter(
metric
.metadata()
.into_iter()
.map(|(k, v)| (k.to_string(), v.to_string())),
),
};
if let Some(description) = metric.description().map(|v| v.to_string()) {
gauge
.metadata
.insert("description".to_string(), description);
}
snapshot.gauges.push(gauge);
}
Some(Value::Other(other)) => {
let histogram = if let Some(histogram) = other.downcast_ref::<AtomicHistogram>()
{
histogram.load()
} else if let Some(histogram) = other.downcast_ref::<RwLockHistogram>() {
histogram.load()
} else {
None
};
if let Some(histogram) = histogram {
let mut metadata = HashMap::from_iter(
metric
.metadata()
.into_iter()
.map(|(k, v)| (k.to_string(), v.to_string())),
);
// Store configuration parameters as metadata
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(),
);
if let Some(description) = metric.description().map(|v| v.to_string()) {
metadata.insert("description".to_string(), description);
}
let histogram = Histogram {
name: metric.formatted(metriken::Format::Simple),
value: histogram,
metadata,
};
snapshot.histograms.push(histogram);
}
}
_ => continue,
}
}
snapshot
}
}