PaperMC/patches/server/0868-Throw-exception-on-world-create-while-being-ticked.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: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Tue, 22 Mar 2022 12:44:30 -0700
Subject: [PATCH] Throw exception on world create while being ticked
There are no plans to support creating worlds while worlds are
being ticked themselvess.
diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
index 41543b69934c5e5c050636482c7d2b93a6bab796..60a84de276885009310904afc90516d6106458d1 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -297,6 +297,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
public volatile Thread shutdownThread; // Paper
public volatile boolean abnormalExit = false; // Paper
+ public boolean isIteratingOverLevels = false; // Paper
public static <S extends MinecraftServer> S spin(Function<Thread, S> serverFactory) {
AtomicReference<S> atomicreference = new AtomicReference();
@@ -1475,7 +1476,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
this.getFunctions().tick();
MinecraftTimings.commandFunctionsTimer.stopTiming(); // Spigot // Paper
this.profiler.popPush("levels");
- Iterator iterator = this.getAllLevels().iterator();
+ //Iterator iterator = this.getAllLevels().iterator(); // Paper - moved down
// CraftBukkit start
// Run tasks that are waiting on processing
@@ -1507,6 +1508,8 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
// Paper end
MinecraftTimings.timeUpdateTimer.stopTiming(); // Spigot // Paper
+ this.isIteratingOverLevels = true; // Paper
+ Iterator iterator = this.getAllLevels().iterator(); // Paper - move down
while (iterator.hasNext()) {
ServerLevel worldserver = (ServerLevel) iterator.next();
worldserver.hasPhysicsEvent = org.bukkit.event.block.BlockPhysicsEvent.getHandlerList().getRegisteredListeners().length > 0; // Paper
@@ -1554,6 +1557,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
this.profiler.pop();
worldserver.explosionDensityCache.clear(); // Paper - Optimize explosions
}
+ this.isIteratingOverLevels = false; // Paper
this.profiler.popPush("connection");
MinecraftTimings.connectionTimer.startTiming(); // Spigot
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftServer.java b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
index 8df7c0c29d8bf37e52994751464cc91e44050792..75aa5bc28fde5d8b542778caeb46b31c57b86e5e 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
@@ -855,6 +855,11 @@ public final class CraftServer implements Server {
return new ArrayList<World>(this.worlds.values());
}
+ @Override
+ public boolean isTickingWorlds() {
+ return console.isIteratingOverLevels;
+ }
+
public DedicatedPlayerList getHandle() {
return this.playerList;
}
@@ -1139,6 +1144,7 @@ public final class CraftServer implements Server {
@Override
public World createWorld(WorldCreator creator) {
Preconditions.checkState(this.console.getAllLevels().iterator().hasNext(), "Cannot create additional worlds on STARTUP");
+ //Preconditions.checkState(!this.console.isIteratingOverLevels, "Cannot create a world while worlds are being ticked"); // Paper - Cat - Temp disable. We'll see how this goes.
Validate.notNull(creator, "Creator may not be null");
String name = creator.name();
@@ -1263,6 +1269,7 @@ public final class CraftServer implements Server {
@Override
public boolean unloadWorld(World world, boolean save) {
+ //Preconditions.checkState(!this.console.isIteratingOverLevels, "Cannot unload a world while worlds are being ticked"); // Paper - Cat - Temp disable. We'll see how this goes.
if (world == null) {
return false;
}