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, 63 insertions, 0 deletions

diff --git a/patches/server/0024-Drop-falling-block-and-tnt-entities-at-the-specified.patch b/patches/server/0024-Drop-falling-block-and-tnt-entities-at-the-specified.patch
new file mode 100644
index 0000000000..ed1b412de9
--- /dev/null
+++ b/patches/server/0024-Drop-falling-block-and-tnt-entities-at-the-specified.patch
@@ -0,0 +1,63 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Byteflux <[email protected]>
+Date: Tue, 1 Mar 2016 14:14:15 -0600
+Subject: [PATCH] Drop falling block and tnt entities at the specified height
+
+* Dec 2, 2020 Added tnt nerf for tnt minecarts - Machine_Maker
+
+diff --git a/src/main/java/net/minecraft/world/entity/item/FallingBlockEntity.java b/src/main/java/net/minecraft/world/entity/item/FallingBlockEntity.java
+index 7e1594e8df4fd09cd1aecbc5f3784797b04a8337..bd357c3e6fcbd82f3c53ecc8dab46aa5d3708bc2 100644
+--- a/src/main/java/net/minecraft/world/entity/item/FallingBlockEntity.java
++++ b/src/main/java/net/minecraft/world/entity/item/FallingBlockEntity.java
+@@ -137,6 +137,17 @@ public class FallingBlockEntity extends Entity {
+             }
+ 
+             this.move(MoverType.SELF, this.getDeltaMovement());
++
++            // Paper start - Configurable EntityFallingBlock height nerf
++            if (this.level.paperConfig().fixes.fallingBlockHeightNerf != 0 && this.getY() > this.level.paperConfig().fixes.fallingBlockHeightNerf) {
++                if (this.dropItem && this.level.getGameRules().getBoolean(GameRules.RULE_DOENTITYDROPS)) {
++                    this.spawnAtLocation(block);
++                }
++
++                this.discard();
++                return;
++            }
++            // Paper end
+             if (!this.level.isClientSide) {
+                 BlockPos blockposition = this.blockPosition();
+                 boolean flag = this.blockState.getBlock() instanceof ConcretePowderBlock;
+diff --git a/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java b/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
+index e24b46820394c5f220d5bf7c4e763ef95ff9e9ab..2d4a990da2402a6c24c03e8be7e518e33db99c8f 100644
+--- a/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
++++ b/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
+@@ -68,6 +68,12 @@ public class PrimedTnt extends Entity {
+         }
+ 
+         this.move(MoverType.SELF, this.getDeltaMovement());
++        // Paper start - Configurable TNT entity height nerf
++        if (this.level.paperConfig().fixes.tntEntityHeightNerf != 0 && this.getY() > this.level.paperConfig().fixes.tntEntityHeightNerf) {
++            this.discard();
++            return;
++        }
++        // Paper end
+         this.setDeltaMovement(this.getDeltaMovement().scale(0.98D));
+         if (this.onGround) {
+             this.setDeltaMovement(this.getDeltaMovement().multiply(0.7D, -0.5D, 0.7D));
+diff --git a/src/main/java/net/minecraft/world/entity/vehicle/MinecartTNT.java b/src/main/java/net/minecraft/world/entity/vehicle/MinecartTNT.java
+index c10c28eb441e65c6285c25b5d4760c876909c724..136bd0168b573079dfad127d02ca8ba72c02fafb 100644
+--- a/src/main/java/net/minecraft/world/entity/vehicle/MinecartTNT.java
++++ b/src/main/java/net/minecraft/world/entity/vehicle/MinecartTNT.java
+@@ -46,6 +46,12 @@ public class MinecartTNT extends AbstractMinecart {
+     public void tick() {
+         super.tick();
+         if (this.fuse > 0) {
++            // Paper start - Configurable TNT entity height nerf
++            if (this.level.paperConfig().fixes.tntEntityHeightNerf != 0 && this.getY() > this.level.paperConfig().fixes.tntEntityHeightNerf) {
++                this.discard();
++                return;
++            }
++            // Paper end
+             --this.fuse;
+             this.level.addParticle(ParticleTypes.SMOKE, this.getX(), this.getY() + 0.5D, this.getZ(), 0.0D, 0.0D, 0.0D);
+         } else if (this.fuse == 0) {