mixtrics 0.2.3

One crate for all metrics.
Documentation 
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// Copyright 2025 mixtrics Project Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! A no-op metrics backend useful for tests and benchmarks.
//!
//! This module provides [`NoopMetricsRegistry`](crate::registry::noop::NoopMetricsRegistry), an implementation of the
//! [`RegistryOps`](crate::metrics::RegistryOps) trait that silently discards all metrics updates. It is handy for
//! scenarios where you need to satisfy an instrumentation dependency without wiring a real metrics sink.

use std::borrow::Cow;

use crate::metrics::{
    BoxedCounter, BoxedCounterVec, BoxedGauge, BoxedGaugeVec, BoxedHistogram, BoxedHistogramVec, CounterOps,
    CounterVecOps, GaugeOps, GaugeVecOps, HistogramOps, HistogramVecOps, RegistryOps,
};

/// Noop metrics placeholder.
#[derive(Debug)]
pub struct NoopMetricsRegistry;

impl CounterOps for NoopMetricsRegistry {
    fn increase(&self, _: u64) {}
}

impl CounterVecOps for NoopMetricsRegistry {
    fn counter(&self, _: &[Cow<'static, str>]) -> BoxedCounter {
        Box::new(NoopMetricsRegistry)
    }
}

impl GaugeOps for NoopMetricsRegistry {
    fn increase(&self, _: u64) {}

    fn decrease(&self, _: u64) {}

    fn absolute(&self, _: u64) {}
}

impl GaugeVecOps for NoopMetricsRegistry {
    fn gauge(&self, _: &[Cow<'static, str>]) -> BoxedGauge {
        Box::new(NoopMetricsRegistry)
    }
}

impl HistogramOps for NoopMetricsRegistry {
    fn record(&self, _: f64) {}
}

impl HistogramVecOps for NoopMetricsRegistry {
    fn histogram(&self, _: &[Cow<'static, str>]) -> BoxedHistogram {
        Box::new(NoopMetricsRegistry)
    }
}

impl RegistryOps for NoopMetricsRegistry {
    fn register_counter_vec(
        &self,
        _: Cow<'static, str>,
        _: Cow<'static, str>,
        _: &'static [&'static str],
    ) -> BoxedCounterVec {
        Box::new(NoopMetricsRegistry)
    }

    fn register_gauge_vec(
        &self,
        _: Cow<'static, str>,
        _: Cow<'static, str>,
        _: &'static [&'static str],
    ) -> BoxedGaugeVec {
        Box::new(NoopMetricsRegistry)
    }

    fn register_histogram_vec(
        &self,
        _: Cow<'static, str>,
        _: Cow<'static, str>,
        _: &'static [&'static str],
    ) -> BoxedHistogramVec {
        Box::new(NoopMetricsRegistry)
    }

    fn register_histogram_vec_with_buckets(
        &self,
        _: Cow<'static, str>,
        _: Cow<'static, str>,
        _: &'static [&'static str],
        _: Vec<f64>,
    ) -> BoxedHistogramVec {
        Box::new(NoopMetricsRegistry)
    }
}

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

    #[test]
    fn test() {
        let noop = NoopMetricsRegistry;

        let cv = noop.register_counter_vec("test_counter_1".into(), "test counter 1".into(), &["label1", "label2"]);
        let c = cv.counter(&["l1".into(), "l2".into()]);
        c.increase(42);

        let gv = noop.register_gauge_vec("test_gauge_1".into(), "test gauge 1".into(), &["label1", "label2"]);
        let g = gv.gauge(&["l1".into(), "l2".into()]);
        g.increase(514);
        g.decrease(114);
        g.absolute(114514);

        let hv = noop.register_histogram_vec(
            "test_histogram_1".into(),
            "test histogram 1".into(),
            &["label1", "label2"],
        );
        let h = hv.histogram(&["l1".into(), "l2".into()]);
        h.record(114.514);

        let hv = noop.register_histogram_vec_with_buckets(
            "test_histogram_2".into(),
            "test histogram 2".into(),
            &["label1", "label2"],
            vec![1.0, 10.0, 100.0],
        );
        let h = hv.histogram(&["l1".into(), "l2".into()]);
        h.record(114.514);
    }
}