Prometheus.hpp

#pragma once
 
#include "util/log/Logger.hpp"
#include "util/prometheus/Bool.hpp"
#include "util/prometheus/Counter.hpp"
#include "util/prometheus/Gauge.hpp"
#include "util/prometheus/Histogram.hpp"
#include "util/prometheus/Label.hpp"
#include "util/prometheus/MetricBase.hpp"
#include "util/prometheus/MetricsFamily.hpp"
 
#include <concepts>
#include <cstdint>
#include <memory>
#include <optional>
#include <string>
#include <unordered_map>
#include <vector>
 
namespace util::prometheus {

class PrometheusInterface {
public:
    PrometheusInterface(bool isEnabled, bool compressReply)
        : isEnabled_(isEnabled), compressReplyEnabled_(compressReply)
    {
    }
 
    virtual ~PrometheusInterface() = default;

    virtual Bool
    boolMetric(
        std::string name,
        Labels labels,
        std::optional<std::string> description = std::nullopt
    ) = 0;

    virtual CounterInt&
    counterInt(
        std::string name,
        Labels labels,
        std::optional<std::string> description = std::nullopt
    ) = 0;

    virtual CounterDouble&
    counterDouble(
        std::string name,
        Labels labels,
        std::optional<std::string> description = std::nullopt
    ) = 0;

    virtual GaugeInt&
    gaugeInt(
        std::string name,
        Labels labels,
        std::optional<std::string> description = std::nullopt
    ) = 0;

    virtual GaugeDouble&
    gaugeDouble(
        std::string name,
        Labels labels,
        std::optional<std::string> description = std::nullopt
    ) = 0;

    virtual HistogramInt&
    histogramInt(
        std::string name,
        Labels labels,
        std::vector<std::int64_t> const& buckets,
        std::optional<std::string> description = std::nullopt
    ) = 0;

    virtual HistogramDouble&
    histogramDouble(
        std::string name,
        Labels labels,
        std::vector<double> const& buckets,
        std::optional<std::string> description = std::nullopt
    ) = 0;

    virtual std::string
    collectMetrics() = 0;

    bool
    isEnabled() const
    {
        return isEnabled_;
    }

    bool
    compressReplyEnabled() const
    {
        return compressReplyEnabled_;
    }
 
private:
    bool isEnabled_;
    bool compressReplyEnabled_;
};

class PrometheusImpl : public PrometheusInterface {
public:
    using PrometheusInterface::PrometheusInterface;
 
    Bool
    boolMetric(
        std::string name,
        Labels labels,
        std::optional<std::string> description = std::nullopt
    ) override;
 
    CounterInt&
    counterInt(std::string name, Labels labels, std::optional<std::string> description) override;
 
    CounterDouble&
    counterDouble(std::string name, Labels labels, std::optional<std::string> description) override;
 
    GaugeInt&
    gaugeInt(std::string name, Labels labels, std::optional<std::string> description) override;
 
    GaugeDouble&
    gaugeDouble(std::string name, Labels labels, std::optional<std::string> description) override;
 
    HistogramInt&
    histogramInt(
        std::string name,
        Labels labels,
        std::vector<std::int64_t> const& buckets,
        std::optional<std::string> description = std::nullopt
    ) override;
 
    HistogramDouble&
    histogramDouble(
        std::string name,
        Labels labels,
        std::vector<double> const& buckets,
        std::optional<std::string> description = std::nullopt
    ) override;
 
    std::string
    collectMetrics() override;
 
private:
    MetricsFamily&
    getMetricsFamily(std::string name, std::optional<std::string> description, MetricType type);
 
    MetricBase&
    getMetric(
        std::string name,
        Labels labels,
        std::optional<std::string> description,
        MetricType type
    );
 
    template <typename ValueType>
        requires std::same_as<ValueType, std::int64_t> || std::same_as<ValueType, double>
    MetricBase&
    getMetric(
        std::string name,
        Labels labels,
        std::optional<std::string> description,
        MetricType type,
        std::vector<ValueType> const& buckets
    );
 
    std::unordered_map<std::string, MetricsFamily> metrics_;
};
 
}  // namespace util::prometheus

class PrometheusService {
public:
    static void
    init(util::config::ClioConfigDefinition const& config);

    static bool
    isInitialised();

    static util::prometheus::Bool
    boolMetric(
        std::string name,
        util::prometheus::Labels labels,
        std::optional<std::string> description = std::nullopt
    );

    static util::prometheus::CounterInt&
    counterInt(
        std::string name,
        util::prometheus::Labels labels,
        std::optional<std::string> description = std::nullopt
    );

    static util::prometheus::CounterDouble&
    counterDouble(
        std::string name,
        util::prometheus::Labels labels,
        std::optional<std::string> description = std::nullopt
    );

    static util::prometheus::GaugeInt&
    gaugeInt(
        std::string name,
        util::prometheus::Labels labels,
        std::optional<std::string> description = std::nullopt
    );

    static util::prometheus::GaugeDouble&
    gaugeDouble(
        std::string name,
        util::prometheus::Labels labels,
        std::optional<std::string> description = std::nullopt
    );

    static util::prometheus::HistogramInt&
    histogramInt(
        std::string name,
        util::prometheus::Labels labels,
        std::vector<std::int64_t> const& buckets,
        std::optional<std::string> description = std::nullopt
    );

    static util::prometheus::HistogramDouble&
    histogramDouble(
        std::string name,
        util::prometheus::Labels labels,
        std::vector<double> const& buckets,
        std::optional<std::string> description = std::nullopt
    );

    static std::string
    collectMetrics();

    static bool
    isEnabled();

    static bool
    compressReplyEnabled();

    static void
    replaceInstance(std::unique_ptr<util::prometheus::PrometheusInterface> inst);

    static util::prometheus::PrometheusInterface&
    instance();
 
private:
    static std::unique_ptr<util::prometheus::PrometheusInterface> impl;
};