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.

1 files changed, 41 insertions, 0 deletions

diff --git a/patches/server/0522-Limit-recipe-packets.patch b/patches/server/0522-Limit-recipe-packets.patch
new file mode 100644
index 0000000000..f40301fce3
--- /dev/null
+++ b/patches/server/0522-Limit-recipe-packets.patch
@@ -0,0 +1,41 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Shane Freeder <[email protected]>
+Date: Sat, 12 Dec 2020 23:45:28 +0000
+Subject: [PATCH] Limit recipe packets
+
+
+diff --git a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+index 8e12c4d4b54c2f0a265dc627d7981282fc6fda6e..32227020d0cba1aba3ec0fcda5f4b4cd4b1ce394 100644
+--- a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
++++ b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+@@ -263,6 +263,7 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Tic
+     // CraftBukkit start - multithreaded fields
+     private final AtomicInteger chatSpamTickCount = new AtomicInteger();
+     private final java.util.concurrent.atomic.AtomicInteger tabSpamLimiter = new java.util.concurrent.atomic.AtomicInteger(); // Paper - configurable tab spam limits
++    private final java.util.concurrent.atomic.AtomicInteger recipeSpamPackets =  new java.util.concurrent.atomic.AtomicInteger(); // Paper - auto recipe limit
+     // CraftBukkit end
+     private int dropSpamTickCount;
+     private double firstGoodX;
+@@ -425,6 +426,7 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Tic
+         // CraftBukkit start
+         for (int spam; (spam = this.chatSpamTickCount.get()) > 0 && !this.chatSpamTickCount.compareAndSet(spam, spam - 1); ) ;
+         if (tabSpamLimiter.get() > 0) tabSpamLimiter.getAndDecrement(); // Paper - split to seperate variable
++        if (recipeSpamPackets.get() > 0) recipeSpamPackets.getAndDecrement(); // Paper
+         /* Use thread-safe field access instead
+         if (this.chatSpamTickCount > 0) {
+             --this.chatSpamTickCount;
+@@ -3247,6 +3249,14 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Tic
+ 
+     @Override
+     public void handlePlaceRecipe(ServerboundPlaceRecipePacket packet) {
++        // Paper start
++        if (!org.bukkit.Bukkit.isPrimaryThread()) {
++            if (recipeSpamPackets.addAndGet(io.papermc.paper.configuration.GlobalConfiguration.get().spamLimiter.recipeSpamIncrement) > io.papermc.paper.configuration.GlobalConfiguration.get().spamLimiter.recipeSpamLimit) {
++                server.scheduleOnMain(() -> this.disconnect(net.minecraft.network.chat.Component.translatable("disconnect.spam", new Object[0]))); // Paper
++                return;
++            }
++        }
++        // Paper end
+         PacketUtils.ensureRunningOnSameThread(packet, this, this.player.getLevel());
+         this.player.resetLastActionTime();
+         if (!this.player.isSpectator() && this.player.containerMenu.containerId == packet.getContainerId() && this.player.containerMenu instanceof RecipeBookMenu) {