A general-purpose metrics library.

The design of the crate is based fairly closely off of the Dropwizard Metrics library from the Java ecosystem.

Examples

use witchcraft_metrics::{MetricRegistry, MetricId, Metric};
use std::time::Duration;

// A `MetricRegistry` stores metrics.
let registry = MetricRegistry::new();

// Metrics are identified by an ID, which consists of a name and set of "tags"
let yaks_shaved = registry.counter(MetricId::new("shavings").with_tag("animal", "yak"));
// You can also pass a string directly for metric IDs that don't have tags
let request_timer = registry.timer("server.requests");

// do some work and record some values.
for yak in find_some_yaks() {
shave_yak(yak);
yaks_shaved.inc();
}

// Grab a snapshot of the metrics currently registered and print their values:
for (id, metric) in &registry.metrics() {
match metric {
Metric::Counter(counter) => println!("{:?} is a counter with value {}", id, counter.count()),
Metric::Timer(timer) => {
let nanos = timer.snapshot().value(0.99);
let duration = Duration::from_nanos(nanos as u64);
println!("{:?} is a timer with 99th percentile {:?}", id, duration);
}
_ => {}
}
}

# fn find_some_yaks() -> &'static [()] { &[] }
# fn shave_yak(_: &()) {}