synapsecns/sanguine

package metrics

import (
    "context"
    "go.opentelemetry.io/otel/metric"
    "time"
)

// standardMetrics records metrics across any service using the metrics handler.
type standardMetrics struct {
    metrics     Handler
    meter       metric.Meter
    uptimeGauge metric.Float64ObservableGauge
    startTime   time.Time
}

const processUptimeSecondsMetric = "process_uptime_seconds"

func newStandardMetrics(ctx context.Context, handler Handler) {
    str := standardMetrics{
        metrics:   handler,
        meter:     handler.Meter("standard_metrics"),
        startTime: time.Now(),
    }

    var err error
    if str.uptimeGauge, err = str.meter.Float64ObservableGauge(processUptimeSecondsMetric, metric.WithDescription("The uptime of the process in seconds"), metric.WithUnit("seconds")); err != nil {
        handler.ExperimentalLogger().Errorf(ctx, "failed to create %s gauge: %v", processUptimeSecondsMetric, err)
    }

    // Register callback
    if _, err = str.meter.RegisterCallback(str.uptimeCallback, str.uptimeGauge); err != nil {
        handler.ExperimentalLogger().Warnf(ctx, "failed to register callback: %v", err)
    }
}

func (str *standardMetrics) uptimeCallback(_ context.Context, observer metric.Observer) error {
    uptimeDuration := time.Since(str.startTime).Seconds()
    observer.ObserveFloat64(str.uptimeGauge, uptimeDuration)
    return nil
}