simplify data library set up

[mdsumner]

Currently we have run all of these, in order:

raadfiles::set_raad_data_roots(my_data_dir)      
raadfiles:::run_this_function_to_build_raad_cache()
raadfiles:::set_raad_filenames()

The first should trigger invalidate of the others, though perhaps with opt-out / yesno allow of step 2.

[raymondben]

Could set_raad_data_roots() take a build_cache_if_empty parameter that defaults to TRUE? so that pointing to a new data directory automatically triggers its file list build. And also a refresh_cache that defaults to FALSE, so you have to opt in to that one if you're using a data dir that you've used previously. And in either case, yes, calling set_raad_data_roots should trigger set_raad_filenames

-- ignore this one, see https://github.com/AustralianAntarcticDivision/raadtools/pull/80/commits/cd2e12151273597ec4751a76c22d25a0ad8a5db5

[raymondben]

Random comments looking for a home:

• run_this_function_to_build_raad_cache should probably be exported since it's now used within raadtools
• the cache building functions currently operate on an all-or-nothing basis, it might be handy (but not a priority) to be able to refresh a cache for just one root, not all of them

[mdsumner]

I actually got in a fluff because I was running the job and updating the package, not a good idea but did make me wonder if raadfiles should never trigger these tasks on load, and only rely on other packages or an admin to actually run them. That's probably safer, because otherwise the code scheduled to be run depends on the load occurring successfully, and you can get stuck and then you need another worker. It could set an env flag prior to an automated task "no-onload-admin", and that's set for any scheduled task. I'm undecided

[mdsumner]

It seems ok atm, I'll just stay away from cron until I'm sure. :)

[mdsumner]

Pretty fine. We have to set triggers for mount, because they are lost when then the mothership reboots

[mdsumner]

Ok, now we have this for a first time set up, after running bowerbird in "C:/temp/data"

options(raadfiles.file.cache.disable = TRUE)  ## only really needed when raadfiles will find existing stuff
library(raadfiles)
set_raad_data_roots("C:/temp/data")
run_build_raad_cache()  
set_raad_filenames()

[mdsumner]

For subsequent usage, a session looks like

options(raadfiles.data.roots = "C:/temp/data")
library(raadfiles)

but note this will also find other roots using the internal heuristics if they are available - so watch out for that.

[mdsumner]

I do believe we achieved this