Struct MetricRecorder 

pub struct MetricRecorder { /* private fields */ }

Ergonomic plugin-side helper that wraps the FFI recorder.

Plugins embed a MetricRecorder in their state, the define_plugin! macro wires it via the set_metric_recorder vtable entry, and plugin code calls the typed counter / gauge / histogram methods from anywhere with &self.

pub struct MyPlugin {
    metrics: MetricRecorder,
    // ...other state
}

impl MyPlugin {
    fn process(&self, msg: &SpoeMessage) -> Result<ProcessingResult, _> {
        self.metrics.counter("dispatches_total", &[("kind", "ok")], 1);
        self.metrics.histogram("latency_seconds", &[], 0.012);
        // ...
    }
}

When the recorder is not yet installed (between create and the hub’s set_metric_recorder call) or the host is running a v1 hub that never installs one, the methods are inexpensive no-ops — a single relaxed pointer load that observes None.

Implementations

impl MetricRecorder

pub const fn new() -> Self

Construct an uninitialised recorder. Plugins embed this in their state; the define_plugin! macro fills it in when the hub calls set_metric_recorder.

pub fn counter(&self, name: &str, labels: &[(&str, &str)], increment: u64)

Increment a counter. increment is typically 1. Names are hub-namespaced — emitting "dispatches_total" from the mirror plugin lands as plugin_mirror_dispatches_total in Prometheus.

pub fn gauge(&self, name: &str, labels: &[(&str, &str)], value: f64)

Set a gauge. Replaces the previous value for this (name, labels) tuple in the registry.

pub fn histogram(&self, name: &str, labels: &[(&str, &str)], value: f64)

Record a histogram observation. Bucket boundaries are governed by the hub’s Prometheus exporter config; plugins that need custom buckets coordinate with the hub at deploy time.

Trait Implementations

impl Debug for MetricRecorder

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for MetricRecorder

fn default() -> Self

Returns the “default value” for a type.