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, 37 insertions, 0 deletions

diff --git a/patches/server/0486-Expose-the-Entity-Counter-to-allow-plugins-to-use-va.patch b/patches/server/0486-Expose-the-Entity-Counter-to-allow-plugins-to-use-va.patch
new file mode 100644
index 0000000000..fa83ed6181
--- /dev/null
+++ b/patches/server/0486-Expose-the-Entity-Counter-to-allow-plugins-to-use-va.patch
@@ -0,0 +1,37 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: MeFisto94 <[email protected]>
+Date: Fri, 28 Aug 2020 01:41:26 +0200
+Subject: [PATCH] Expose the Entity Counter to allow plugins to use valid and
+ non-conflicting Entity Ids
+
+
+diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
+index 9325d4b5cbcf3785985567deeb9f13e56a4124d0..71b75dd2127c80b782973fdd34be461357042e7d 100644
+--- a/src/main/java/net/minecraft/world/entity/Entity.java
++++ b/src/main/java/net/minecraft/world/entity/Entity.java
+@@ -4162,4 +4162,10 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource {
+ 
+         void accept(Entity entity, double x, double y, double z);
+     }
++
++    // Paper start
++    public static int nextEntityId() {
++        return ENTITY_COUNTER.incrementAndGet();
++    }
++    // Paper end
+ }
+diff --git a/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java b/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
+index c65cc24fbd8b6cb9828fbc978c21c3f7ef9171a3..346f5f4b2afec3127c5d1b8e054eaacb1cb756e4 100644
+--- a/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
++++ b/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
+@@ -502,6 +502,10 @@ public final class CraftMagicNumbers implements UnsafeValues {
+         net.minecraft.world.item.ItemStack nmsItemStack = CraftItemStack.asNMSCopy(itemStack);
+         return nmsItemStack.getItem().getDescriptionId(nmsItemStack);
+     }
++
++    public int nextEntityId() {
++        return net.minecraft.world.entity.Entity.nextEntityId();
++    }
+     // Paper end
+ 
+     /**