Module metrics_registry 

Prometheus-compatible metrics registry (bd-xox.3).

Provides counters, gauges, and histograms that can be exported in Prometheus text exposition format via MetricsRegistry::render.

Design

• Zero-allocation on the hot path: All metric storage uses AtomicU64.
• Lock-free reads: Snapshot is a single pass over atomic loads.
• Label support: Metrics with labels use a fixed set of variants to avoid dynamic allocation and hash maps.
• Histogram: Uses fixed log-scale buckets for O(1) observe.

Usage

use ftui_runtime::metrics_registry::{METRICS, BuiltinCounter, BuiltinGauge, BuiltinHistogram};

// Increment a counter
METRICS.counter(BuiltinCounter::RenderFramesTotal).inc();

// Set a gauge
METRICS.gauge(BuiltinGauge::TerminalActive).set(1);

// Observe a histogram value
METRICS.histogram(BuiltinHistogram::RenderFrameDurationUs).observe(450);

// Export Prometheus text format
let output = METRICS.render();
println!("{output}");

Structs

Counter

A monotonic counter (can only increase).

Gauge

A gauge (can go up or down).

Histogram

Fixed-bucket histogram for latency measurements.

MetricsRegistry

Central metrics registry with fixed-slot storage.

Enums

BuiltinCounter

Builtin counter metrics.

BuiltinGauge

Builtin gauge metrics.

BuiltinHistogram

Builtin histogram metrics.

Statics

METRICS

Global metrics registry instance.