Folsom is an Erlang based metrics system inspired by Coda Hale's metrics
(https://github.com/codahale/metrics/). The metrics API's purpose is to collect
realtime metrics from your Erlang applications and publish them via Erlang APIs
and output plugins. folsom is not a persistent store. There are 6 types of
metrics: counters, gauges, histograms (and timers), histories, meter_readers and
meters. Metrics can be created, read and updated via the folsom_metrics module.