To address this, I don't use the json at all, as it's itself a factory class which provides metadata.

But I couldnt' get rid of it without error.

Typo?

since this is array in/array out, could consistence of naming be improved?
either
sensorsIds/sensorsInfos
or
sensorIds/sensorInfos

needs to be always polling every half a second? could it be somewhat adjustable (maybe depending on ac/on battery?)

if (

copyright?

what's the commandline option missing?

if this timer is needed for compression, shouldn't be the same timer always restarted?
if i call singleshot 10 times, iirc that slot will be invoked delayed 10 times

if () {
}

maybe mapping on a config file?

setMax?

s/=/this/

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0806r2.html

Maybe:

if(auto sensor = m_daemon->findSensor(sensorPath)) {
    ...
}

... = sensor->info();

if (auto sensor = ...)

[=] is evil

clang-format

I'm not going to be bold enough to propose

if (const auto variant = ...; variant.isValid()) { }

const int, const int

This should probably use qAsConst.

Should we do some error logging here? Might help future plugin development.

qAsConst(m_containers)

Like above, objects() should be in a const variable. (Also for sensors on the line below).

qAsConst(m_clients)

It's guarded with "m_dataChangeQueued" which only gets reset after the timer triggers.

Uh, so shouldn't we fix this?

Maybe move this to private with friend class SensorObject? Though I don't really see why this is internal only. Also probably should rename it to addObject?

Indeed, the current code is every 2s. I ramped it up to expose any issues.

I would quite like it to be somewhat container specific.
i.e disk storage doesn't change much, CPU is more volatile.

I'll change it, and then maybe we can revisit this topic once some more things are ported.

Seems like a plan :)

It was just to explicitly enforce the memory management combined with the tree management.

I'll go with private, then we can change if we find we need to

Plan (with some pending code) is to just move these in natively into a more readable plugin