kegani 0.1.0

A developer-friendly, ergonomic, production-ready Rust web framework
Documentation 
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//! Metrics recorder for Kegani
//!
//! Provides Prometheus-compatible metrics.

use std::sync::Arc;
use tokio::sync::RwLock;
use std::collections::HashMap;
use std::time::Duration;

/// Metrics recorder
#[derive(Clone)]
pub struct Metrics {
    counters: Arc<RwLock<HashMap<String, Counter>>>,
    gauges: Arc<RwLock<HashMap<String, Gauge>>>,
    histograms: Arc<RwLock<HashMap<String, Histogram>>>,
}

impl Metrics {
    /// Create a new metrics recorder
    pub fn new() -> Self {
        Self {
            counters: Arc::new(RwLock::new(HashMap::new())),
            gauges: Arc::new(RwLock::new(HashMap::new())),
            histograms: Arc::new(RwLock::new(HashMap::new())),
        }
    }

    /// Get or create a counter
    pub async fn counter(&self, name: &str) -> Counter {
        let mut counters = self.counters.write().await;
        counters
            .entry(name.to_string())
            .or_insert_with(Counter::new)
            .clone()
    }

    /// Get or create a gauge
    pub async fn gauge(&self, name: &str) -> Gauge {
        let mut gauges = self.gauges.write().await;
        gauges
            .entry(name.to_string())
            .or_insert_with(Gauge::new)
            .clone()
    }

    /// Get or create a histogram
    pub async fn histogram(&self, name: &str) -> Histogram {
        let mut histograms = self.histograms.write().await;
        histograms
            .entry(name.to_string())
            .or_insert_with(Histogram::new)
            .clone()
    }

    /// Increment HTTP requests counter
    pub async fn inc_http_requests(&self, method: &str, path: &str, status: u16) {
        let counter = self.counter("http_requests_total").await;
        counter.inc_by(1.0, &[("method", method), ("path", path), ("status", &status.to_string())]).await;
    }

    /// Record HTTP request duration
    pub async fn observe_http_duration(&self, method: &str, path: &str, duration: Duration) {
        let histogram = self.histogram("http_request_duration_seconds").await;
        histogram.observe(duration.as_secs_f64(), &[("method", method), ("path", path)]).await;
    }

    /// Set active connections gauge
    pub async fn set_active_connections(&self, count: usize) {
        let gauge = self.gauge("active_connections").await;
        gauge.set(count as f64, &[]).await;
    }

    /// Export metrics in Prometheus format
    pub async fn export(&self) -> String {
        let mut output = String::new();

        // Export counters
        let counters = self.counters.read().await;
        for (name, counter) in counters.iter() {
            output.push_str(&format!("# HELP {} {}\n", name, name));
            output.push_str(&format!("# TYPE {} counter\n", name));
            for (labels, value) in counter.get_values().await {
                output.push_str(&format!("{}{} {}\n", name, labels, value));
            }
        }

        // Export gauges
        let gauges = self.gauges.read().await;
        for (name, gauge) in gauges.iter() {
            output.push_str(&format!("# HELP {} {}\n", name, name));
            output.push_str(&format!("# TYPE {} gauge\n", name));
            for (labels, value) in gauge.get_values().await {
                output.push_str(&format!("{}{} {}\n", name, labels, value));
            }
        }

        // Export histograms
        let histograms = self.histograms.read().await;
        for (name, histogram) in histograms.iter() {
            output.push_str(&format!("# HELP {} {}\n", name, name));
            output.push_str(&format!("# TYPE {} histogram\n", name));
            for (labels, bucket_data) in histogram.get_buckets().await {
                let bucket_name = format!("{}_bucket", name);
                for data in bucket_data {
                    output.push_str(&format!("{}{{{}le=\"{}\"}} {}\n", bucket_name, labels, data.le, data.count));
                }
            }
            output.push_str(&format!("{}_sum{} {}\n", name, "", histogram.get_sum().await));
            output.push_str(&format!("{}_count{} {}\n", name, "", histogram.get_count().await));
        }

        output
    }
}

impl Default for Metrics {
    fn default() -> Self {
        Self::new()
    }
}

/// Counter metric
#[derive(Clone)]
pub struct Counter {
    values: Arc<RwLock<HashMap<String, f64>>>,
    labels: Arc<RwLock<HashMap<String, Vec<(String, String)>>>>,
}

impl Counter {
    pub fn new() -> Self {
        Self {
            values: Arc::new(RwLock::new(HashMap::new())),
            labels: Arc::new(RwLock::new(HashMap::new())),
        }
    }

    pub async fn inc(&self, labels: &[(&str, &str)]) {
        let key = Self::labels_to_key(labels);
        let mut values = self.values.write().await;
        *values.entry(key.clone()).or_insert(0.0) += 1.0;

        let mut all_labels = self.labels.write().await;
        all_labels.insert(key, labels.iter().map(|(k, v)| (k.to_string(), v.to_string())).collect());
    }

    pub async fn inc_by(&self, value: f64, labels: &[(&str, &str)]) {
        let key = Self::labels_to_key(labels);
        let mut values = self.values.write().await;
        *values.entry(key.clone()).or_insert(0.0) += value;

        let mut all_labels = self.labels.write().await;
        all_labels.insert(key, labels.iter().map(|(k, v)| (k.to_string(), v.to_string())).collect());
    }

    pub async fn get_values(&self) -> Vec<(String, f64)> {
        let values = self.values.read().await;
        let labels = self.labels.read().await;

        values
            .iter()
            .map(|(k, v)| {
                let label_str = labels.get(k)
                    .map(|l| l.iter().map(|(k, v)| format!("{}=\"{}\"", k, v)).collect::<Vec<_>>().join(","))
                    .unwrap_or_default();
                (format!("{{{}}}", label_str), *v)
            })
            .collect()
    }

    fn labels_to_key(labels: &[(&str, &str)]) -> String {
        labels.iter().map(|(k, v)| format!("{}={}", k, v)).collect::<Vec<_>>().join(",")
    }
}

impl Default for Counter {
    fn default() -> Self {
        Self::new()
    }
}

/// Gauge metric
#[derive(Clone)]
pub struct Gauge {
    values: Arc<RwLock<HashMap<String, f64>>>,
    labels: Arc<RwLock<HashMap<String, Vec<(String, String)>>>>,
}

impl Gauge {
    pub fn new() -> Self {
        Self {
            values: Arc::new(RwLock::new(HashMap::new())),
            labels: Arc::new(RwLock::new(HashMap::new())),
        }
    }

    pub async fn set(&self, value: f64, labels: &[(&str, &str)]) {
        let key = Self::labels_to_key(labels);
        let mut values = self.values.write().await;
        values.insert(key.clone(), value);

        let mut all_labels = self.labels.write().await;
        all_labels.insert(key, labels.iter().map(|(k, v)| (k.to_string(), v.to_string())).collect());
    }

    pub async fn inc(&self, labels: &[(&str, &str)]) {
        let key = Self::labels_to_key(labels);
        let mut values = self.values.write().await;
        *values.entry(key.clone()).or_insert(0.0) += 1.0;
    }

    pub async fn dec(&self, labels: &[(&str, &str)]) {
        let key = Self::labels_to_key(labels);
        let mut values = self.values.write().await;
        *values.entry(key.clone()).or_insert(0.0) -= 1.0;
    }

    pub async fn get_values(&self) -> Vec<(String, f64)> {
        let values = self.values.read().await;
        let labels = self.labels.read().await;

        values
            .iter()
            .map(|(k, v)| {
                let label_str = labels.get(k)
                    .map(|l| l.iter().map(|(k, v)| format!("{}=\"{}\"", k, v)).collect::<Vec<_>>().join(","))
                    .unwrap_or_default();
                (format!("{{{}}}", label_str), *v)
            })
            .collect()
    }

    fn labels_to_key(labels: &[(&str, &str)]) -> String {
        labels.iter().map(|(k, v)| format!("{}={}", k, v)).collect::<Vec<_>>().join(",")
    }
}

impl Default for Gauge {
    fn default() -> Self {
        Self::new()
    }
}

/// Histogram metric
#[derive(Clone)]
pub struct Histogram {
    buckets: Arc<RwLock<HashMap<String, Vec<BucketData>>>>,
    sum: Arc<RwLock<HashMap<String, f64>>>,
    count: Arc<RwLock<HashMap<String, u64>>>,
}

#[derive(Debug, Clone)]
pub struct BucketData {
    le: f64,
    count: u64,
}

impl Histogram {
    pub fn new() -> Self {
        Self {
            buckets: Arc::new(RwLock::new(HashMap::new())),
            sum: Arc::new(RwLock::new(HashMap::new())),
            count: Arc::new(RwLock::new(HashMap::new())),
        }
    }

    pub async fn observe(&self, value: f64, labels: &[(&str, &str)]) {
        let key = Self::labels_to_key(labels);

        // Update sum
        let mut sum = self.sum.write().await;
        *sum.entry(key.clone()).or_insert(0.0) += value;

        // Update count
        let mut count = self.count.write().await;
        *count.entry(key.clone()).or_insert(0) += 1;

        // Update buckets
        let bucket_bounds = vec![0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1.0, 2.5, 5.0, 10.0];
        let mut buckets = self.buckets.write().await;

        for bound in bucket_bounds {
            if value <= bound {
                if let Some(bucket) = buckets.entry(key.clone()).or_insert_with(|| {
                    vec![BucketData { le: 0.005, count: 0 }; 11]
                }).iter_mut().find(|b| b.le == bound) {
                    bucket.count += 1;
                }
            }
        }
    }

    pub async fn get_buckets(&self) -> Vec<(String, Vec<BucketData>)> {
        let buckets = self.buckets.read().await;
        buckets.iter().map(|(k, v)| (k.clone(), v.clone())).collect()
    }

    pub async fn get_sum(&self) -> f64 {
        let sum = self.sum.read().await;
        sum.values().sum()
    }

    pub async fn get_count(&self) -> u64 {
        let count = self.count.read().await;
        count.values().sum()
    }

    fn labels_to_key(labels: &[(&str, &str)]) -> String {
        labels.iter().map(|(k, v)| format!("{}={}", k, v)).collect::<Vec<_>>().join(",")
    }
}

impl Default for Histogram {
    fn default() -> Self {
        Self::new()
    }
}