NBT request, and saving/ loading private data

[Jershy]

In my mod i need to be able to load an unload these Chunks of Chunks essentially. The 'chunk-chunks' contain 4096 objects that hold the variables that represent different surface temperatures and such for each minecraft chunk. So that when a function need say the percentage of the surface of a certain chunk covered in water block, surface temperature (which is defined by time of year and light level) it will be able to call on one of the "chunks". The problem is i don't know how to load and unload each of the chunk-chunks at any given time. Holding them all in the computers memory is completely absurd. How will i be able to call the nbt that I need if one of these chunk-chunks come into render distance.

[Draco18s]

Just as a pre-emptive warning:

These events do not fire in a consistent* way and these events are asynchronous, meaning that any data structures you use to track data will need to be thread-safe or you'll get concurrent modification errors.

 

*By which I mean "use this for X and that for Y."  There are two Save events fired when a chunk unloads, called from different points in the code.  One of those points is after a chunk has been marked as unloaded and will see the chunk removed from memory.  The other is simply a write-to-disk pass and the chunk may or may not be on its way to being unloaded.

The best way I've found to handle clearing data from ram for when a chunk unloads is to use the Save event and check

if(!chunk.isLoaded)

Likewise, the Unload event doesn't give you access to the chunk NBT to save anything.