handler_impl.hpp

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#ifndef KAGOME_CORE_METRICS_IMPL_PROMETHEUS_HANDLER_IMPL_HPP
#define KAGOME_CORE_METRICS_IMPL_PROMETHEUS_HANDLER_IMPL_HPP

#include <functional>
#include <memory>
#include <string_view>

#include <prometheus/collectable.h>
#include "log/logger.hpp"
#include "metrics/handler.hpp"

namespace kagome::metrics {

  class PrometheusHandler : public Handler {
   public:
    explicit PrometheusHandler();
    ~PrometheusHandler() override = default;

    void registerCollectable(Registry &registry) override;

    void onSessionRequest(Session::Request request,
                          std::shared_ptr<Session> session) override;

   private:
    void registerCollectable(
        const std::weak_ptr<prometheus::Collectable> &collectable);
    void removeCollectable(
        const std::weak_ptr<prometheus::Collectable> &collectable);
    static void cleanupStalePointers(
        std::vector<std::weak_ptr<prometheus::Collectable>> &collectables);
    std::size_t writeResponse(std::shared_ptr<Session> session,
                              Session::Request request,
                              const std::string &body);

    std::mutex collectables_mutex_;
    std::vector<std::weak_ptr<prometheus::Collectable>> collectables_;

    log::Logger logger_;
  };

}  // namespace kagome::metrics

#endif  // KAGOME_CORE_METRICS_IMPL_HANDLER_IMPL_HPP