Macro build_metrics_service 

macro_rules! build_metrics_service {
    ($service:ident, $($metric_attribute:ident:$metric_type:ident ($name:literal, $help:literal $(, $labels:expr)?)),*) => { ... };
}

Create a MetricService.

To build the service you need to provide the structure name and a list of metrics. Each metrics is defined by an attribute name, a type, a metric name and a help message.

The attribute name will be used to create a getter method for the metric.

Crate that use this macro should have paste as dependency.

Example of ‘build_metrics_service’ and metrics usage

    use slog::Logger;
    use mithril_common::{entities::Epoch, StdResult};
    use mithril_metric::build_metrics_service;
    use mithril_metric::{MetricCollector, MetricCounter, MetricCounterWithLabels, MetricGauge, MetricsServiceExporter};

    build_metrics_service!(
        MetricsService,
        counter_example: MetricCounter(
            "custom_counter_example_name",
            "Example of a counter metric"
        ),
        gauge_example: MetricGauge(
            "custom_gauge_example_name",
            "Example of a gauge metric"
        ),
        counter_with_labels_example: MetricCounterWithLabels(
            "custom_counter_with_labels_example_name",
            "Example of a counter with labels metric",
            &["label"]
        )
    );

    let service = MetricsService::new(Logger::root(slog::Discard, slog::o!())).unwrap();
    service.get_counter_example().increment();
    service.get_gauge_example().record(Epoch(12));
    service.get_counter_with_labels_example().increment(&["guest"]);