tree 0babce6798a0235e1a15e0c18d97f3a61b4a1044
parent 6efb8ca9ae45205a4a0f71855a64e45a47b0bfe4
author Jan Kundrát <jan.kundrat@cesnet.cz> 1604322176 +0100
committer Jan Kundrát <jan.kundrat@cesnet.cz> 1604326537 +0100

Produce more useful error messages

A typical configuration on a physical box right now includes just one
input source which watches all systemd units on a system. When a change
happens, this source produced a `trace` message which was not visible by
default, and the manager logged a `debug` message (which was visible via
br2-external's config). However, no useful information can be provided
in the StateManager because essentially all the events are generated by
just a single input source, so they are "masked" behind a single source.

Solve this by changing the logging priorities, and also tweak the
messages a bit so that they include more details about what's going on
and fewer assumptions about velia's internal structure.

Instead of this:

 main[276]: Input 0x15edb4c changed state to State::OK
 main[276]: Output changed to State::OK

...now we get this:

 main[675]: Systemd unit 'dev-ttyS2.device' changed state (active plugged)
 main[675]: Status: State::OK

At first I tried to implement this via enforcing all input sources to
inherit from AbstractInput and extending that class with a `std::string
what() const` method, but that did not work because all systemd events
are sent by a single source.

Change-Id: I45873dba3d0314c8192b00b77f608c3b8d6591d9