This is libprom -- the C-client library for Prometheus from
https://github.com/digitalocean/prometheus-client-c.

This project provides this shared library for instrumenting software via
Prometheus.

  libprom: Provides the core API. Resources such as counters, gauges,
           histograms, and collector registries can be found
           here. This library has no dependencies on third-party
           libraries; however, it does rely on pthreads native to
           POSIX systems.