When ChunkAccess was converted to an abstract class some versions
ago, the code to initialise nibble arrays should have been moved.
However, the code was not moved and so now mods constructing their
own implementations of ChunkAccess would not have the nibble arrays
initialised.
This is ported to Paper from Starlight to keep the code base in sync,
not because it fixes anything known.
During feature generation, light data is not initialised and
will always return 15 in Starlight. Vanilla can possibly return
0 if partially initialised, which allows some mushroom blocks to
generate.
In general, the brightness value from the light engine should not
be used until the chunk is ready. To emulate Vanilla behavior better,
we return 0 as the brightness during world gen unless the target
chunk is finished lighting.
The regular light retrieval outside of WorldGenRegion remains
the same, as behaviorally chunks not lit should be at max
skylight and zero block light.
There is no point in initialising the sources in Starlight,
as we do not use them. Additionally, they are not saved to
disk so we do not need them.
Maintaining and initialising them is not a negligible cost,
which is why they are being removed.
We can avoid multiple ticket additions for the same ChunkTasks
instance. This will help in situations where significant number of
block updates occur for the same chunk in the same tick, such as
water draining.
Patch documentation to come
Issues with the old system that are fixed now:
- World generation does not scale with cpu cores effectively.
- Relies on the main thread for scheduling and maintaining chunk state, dropping chunk load/generate rates at lower tps.
- Unreliable prioritisation of chunk gen/load calls that block the main thread.
- Shutdown logic is utterly unreliable, as it has to wait for all chunks to unload - is it guaranteed that the chunk system is in a state on shutdown that it can reliably do this? Watchdog shutdown also typically failed due to thread checks, which is now resolved.
- Saving of data is not unified (i.e can save chunk data without saving entity data, poses problems for desync if shutdown is really abnormal.
- Entities are not loaded with chunks. This caused quite a bit of headache for Chunk#getEntities API, but now the new chunk system loads entities with chunks so that they are ready whenever the chunk loads in. Effectively brings the behavior back to 1.16 era, but still storing entities in their own separate regionfiles.
The above list is not complete. The patch documentation will complete it.
New chunk system hard relies on starlight and dataconverter, and most importantly the new concurrent utilities in ConcurrentUtil.
Some of the old async chunk i/o interface (i.e the old file io thread reroutes _some_ calls to the new file io thread) is kept for plugin compat reasons. It will be removed in the next major version of minecraft.
The old legacy chunk system patches have been moved to the removed folder in case we need them again.
2022-09-26 01:02:51 -07:00
Renamed from patches/server/Rewrite-the-light-engine.patch (Browse further)
