WorldProviders now have the following requirements removed:
- __construct() is no longer required to have a specific signature
- static isValid() no longer needs to be implemented (you will still need it for registering, but it can be declared anywhere now)
- static generate() no longer needs to be implemented
This paves the way for more interesting types of world providers that use something other than local disk to store chunks (e.g. a mysql database).
WorldProviderManager no longer accepts class-string<WorldProvider>. Instead, WorldProviderManagerEntry is required, with 2 or 3 callbacks:
- ReadOnlyWorldProviderManager must provide a callback for isValid, and a callback for fromPath
- WritableWorldProviderManagerEntry must provide the same, and also a generate() callback
In practice, this requires zero changes to the WorldProviders themselves, since a WorldProviderManagerEntry can be created like this:
`new WritableWorldProviderManagerEntry(\Closure::fromCallable([LevelDB::class, 'isValid']), fn(string ) => new LevelDB(), \Closure::fromCallable([LevelDB::class, 'generate']))`
This provides identical functionality to before for the provider itself; only registration is changed.
this can fail if the backups directory points to a different drive than the original worlds location. In this case, we have to copy and delete the files instead, which is much slower, but works.
I REALLY advise against putting backups on a different mount point than worlds if you plan to convert large worlds.
this is slightly slower, but saves a significant amount of memory (~80 KB per chunk).
Since ext-chunkutils2 doesn't do copy-on-write trickery like the PHP impl did, we need this to get the memory advantages back.
a non-generated chunk is now always represented by NULL. This forces the case of ungenerated chunks to be handled by all code, which is necessary because ungenerated chunks cannot be interacted with or modified in any meaningful way.
in cases like PopulationTask it makes more sense to store the coordinates separately where they can be stored more efficiently (once instead of 9 times)
In addition, PopulationTask shouldn't need to serialize an empty chunk just to copy coordinates.
I've made changes like this in other areas already in preparation for the day when chunks no longer contain their coordinates, so this brings us one step closer to that goal.
I think we should probably get rid of this considering the potential for inconsistencies within a chunk, but not retaining this is a bug nonetheless, even though it doesn't have any effect in PM itself since we always use BlockLegacyIds << 4 as the empty block ID.
so, this is only really aiding (ab)use cases which weren't intended anyway ...
this better describes the purpose, which is to identify air.
though, it might make more sense to make air just always have zero as air's runtime ID, since this parameter is apparently making plugin devs think that this is suitable to fill a chunk with a specific block ...
