[tor-dev] tor relay process health data for operators (controlport)

[grarpamp]

All sorts of statistical counters could be useful to graph
from some API... a control port stats dump in something
like var=value, a BSD sysctl text format, and even up to
a proper SNMP port which many graphers already speak.

Logging isn't really the right place for such things,
unless they've reached some preset or unusual
threshold, thus becoming reportable.