ulog logs the supplied message using the ulog
facility which typically corresponsed to syslog. See ulog
Rserve configuration for the various endpoints supported by ulog
(local, UDP/TCP remote, ...).
This function is guaranteed to be silent regardless of the ulog
setting and is intended to have minimal performance impact.
Note: if Rserve is compiled with -DULOG_STDERR (also
implied in the debug build) then ulog messages are also emitted
on stderr with "ULOG: " prefix.
Please note that this ulog function is governed by the Rserve
settings, and NOT the ulog package settings. The latter is a
general port of the ulog logging facility to R, while
Rserve::ulog is specific to to the Rserve process.