Refactor meminfo

[codefiles]

Part of #4149

[svartkanin]

I get the intention of the issue and the improvement approach but this changes the behavior of reading these values from a cached property to re-reading it every time which I don't thing we want.
For this particular one it's not that big a deal as it's only used once, is there a way we could keep the caching around?

[codefiles]

I agree with avoiding re-reading and I am glad you are looking out for that.

As _sys_info is replaced in future pull requests, no more than a single read for a file will occur even if the data is needed in various locations. There will be a site where a function is called and a single read occurs then the data will be passed where needed from that location. It will be passed rather than re-read, caching is not needed to facilitate this.

In the current design, which uses cached_property, the dict returned by mem_info() will be kept in memory after first access for as long as the hardware module is being utilized since _sys_info is a module-level variable. This is unnecessary overhead because only two values from the dict ever get accessed and early in execution.

I would also recommend against force caching something that contains dynamic values.

As always, thank you for reviewing.

[svartkanin]

If there are other iterations coming then I don't mind gettting this in.

I do agree that the dynamic values shouldn't be cached but in this case they are hardware values from the underlying system so I think it'd be a fair assumption to say they will never change.

[codefiles]

MemFree and MemAvailable are dynamic as are other values in /proc/meminfo.