PaperMC/patches/server/0721-Make-sure-inlined-getChunkAt-has-inlined-logic-for-l.patch
Spottedleaf 01a13871de
Rewrite chunk system (#8177)
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

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Sun, 20 Sep 2020 16:10:49 -0700
Subject: [PATCH] Make sure inlined getChunkAt has inlined logic for loaded
chunks
Tux did some profiling some time ago and showed that the
previous getChunkAt method which had inlined logic for loaded
chunks did get inlined, but the standard CPS.getChunkAt
method was not inlined.
Paper recently reverted this optimisation, so it's been reintroduced
here.
diff --git a/src/main/java/net/minecraft/world/level/Level.java b/src/main/java/net/minecraft/world/level/Level.java
index 4a3cfc66fdbff749f098a384c16a2c7cfc72e294..b94af31814c251a9b4b575c206de9807df696c62 100644
--- a/src/main/java/net/minecraft/world/level/Level.java
+++ b/src/main/java/net/minecraft/world/level/Level.java
@@ -367,6 +367,15 @@ public abstract class Level implements LevelAccessor, AutoCloseable {
@Override
public final LevelChunk getChunk(int chunkX, int chunkZ) { // Paper - final to help inline
+ // Paper start - make sure loaded chunks get the inlined variant of this function
+ net.minecraft.server.level.ServerChunkCache cps = ((ServerLevel)this).getChunkSource();
+ if (cps.mainThread == Thread.currentThread()) {
+ LevelChunk ifLoaded = cps.getChunkAtIfLoadedMainThread(chunkX, chunkZ);
+ if (ifLoaded != null) {
+ return ifLoaded;
+ }
+ }
+ // Paper end - make sure loaded chunks get the inlined variant of this function
return (LevelChunk) this.getChunk(chunkX, chunkZ, ChunkStatus.FULL, true); // Paper - avoid a method jump
}