PaperMC/patches/removed/1.19.2-legacy-chunksystem/0725-Do-not-allow-ticket-level-changes-while-unloading-pl.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@spottedleaf.dev>
Date: Sat, 19 Sep 2020 15:29:16 -0700
Subject: [PATCH] Do not allow ticket level changes while unloading
playerchunks
Sync loading the chunk at this stage would cause it to load
older data, as well as screwing our region state.
diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
index a3fceb2608b3be80941dfe2570999b270429e0c6..b34c90497a5492c289839ba74df9f2f27e29370e 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -316,6 +316,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
}
// Paper end
+ boolean unloadingPlayerChunk = false; // Paper - do not allow ticket level changes while unloading chunks
public ChunkMap(ServerLevel world, LevelStorageSource.LevelStorageAccess session, DataFixer dataFixer, StructureTemplateManager structureTemplateManager, Executor executor, BlockableEventLoop<Runnable> mainThreadExecutor, LightChunkGetter chunkProvider, ChunkGenerator chunkGenerator, ChunkProgressListener worldGenerationProgressListener, ChunkStatusUpdateListener chunkStatusChangeListener, Supplier<DimensionDataStorage> persistentStateManagerFactory, int viewDistance, boolean dsync) {
super(session.getDimensionPath(world.dimension()).resolve("region"), dataFixer, dsync);
// Paper - don't copy
@@ -731,6 +732,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
@Nullable
ChunkHolder updateChunkScheduling(long pos, int level, @Nullable ChunkHolder holder, int k) {
+ if (this.unloadingPlayerChunk) { net.minecraft.server.MinecraftServer.LOGGER.error("Cannot tick distance manager while unloading playerchunks", new Throwable()); throw new IllegalStateException("Cannot tick distance manager while unloading playerchunks"); } // Paper
if (k > ChunkMap.MAX_CHUNK_DISTANCE && level > ChunkMap.MAX_CHUNK_DISTANCE) {
return holder;
} else {
@@ -945,6 +947,12 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
if (completablefuture1 != completablefuture) {
this.scheduleUnload(pos, holder);
} else {
+ // Paper start - do not allow ticket level changes while unloading chunks
+ org.spigotmc.AsyncCatcher.catchOp("playerchunk unload");
+ boolean unloadingBefore = this.unloadingPlayerChunk;
+ this.unloadingPlayerChunk = true;
+ try {
+ // Paper end - do not allow ticket level changes while unloading chunks
// Paper start
boolean removed;
if ((removed = this.pendingUnloads.remove(pos, holder)) && ichunkaccess != null) {
@@ -978,6 +986,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
} else if (removed) { // Paper start
net.minecraft.server.ChunkSystem.onChunkHolderDelete(this.level, holder);
} // Paper end
+ } finally { this.unloadingPlayerChunk = unloadingBefore; } // Paper - do not allow ticket level changes while unloading chunks
}
};
diff --git a/src/main/java/net/minecraft/server/level/ServerChunkCache.java b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
index f3ab1691948c46477888776d28791ce24e7aa93d..29ba8971ceffbac68290f6063a69c98065e9bcba 100644
--- a/src/main/java/net/minecraft/server/level/ServerChunkCache.java
+++ b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
@@ -632,6 +632,7 @@ public class ServerChunkCache extends ChunkSource {
public boolean runDistanceManagerUpdates() {
if (distanceManager.delayDistanceManagerTick) return false; // Paper - Chunk priority
+ if (this.chunkMap.unloadingPlayerChunk) { LOGGER.error("Cannot tick distance manager while unloading playerchunks", new Throwable()); throw new IllegalStateException("Cannot tick distance manager while unloading playerchunks"); } // Paper
boolean flag = this.distanceManager.runAllUpdates(this.chunkMap);
boolean flag1 = this.chunkMap.promoteChunkMap();