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, 223 insertions, 0 deletions

diff --git a/patches/server/0829-More-Projectile-API.patch b/patches/server/0829-More-Projectile-API.patch
new file mode 100644
index 0000000000..d15949da57
--- /dev/null
+++ b/patches/server/0829-More-Projectile-API.patch
@@ -0,0 +1,223 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Owen1212055 <[email protected]>
+Date: Tue, 22 Jun 2021 23:41:11 -0400
+Subject: [PATCH] More Projectile API
+
+Co-authored-by: Nassim Jahnke <[email protected]>
+
+diff --git a/src/main/java/net/minecraft/world/entity/projectile/ThrownPotion.java b/src/main/java/net/minecraft/world/entity/projectile/ThrownPotion.java
+index fee09e6ff72cf1da389d5811dd005642cd50a5b4..4f276b2a86735a2c664738450ae0fbdd82031d4e 100644
+--- a/src/main/java/net/minecraft/world/entity/projectile/ThrownPotion.java
++++ b/src/main/java/net/minecraft/world/entity/projectile/ThrownPotion.java
+@@ -98,6 +98,11 @@ public class ThrownPotion extends ThrowableItemProjectile implements ItemSupplie
+     @Override
+     protected void onHit(HitResult hitResult) {
+         super.onHit(hitResult);
++        // Paper start - More projectile API
++        this.splash(hitResult);
++    }
++    public void splash(@org.jetbrains.annotations.Nullable HitResult hitResult) {
++        // Paper end - More projectile API
+         if (!this.level.isClientSide) {
+             ItemStack itemstack = this.getItem();
+             Potion potionregistry = PotionUtils.getPotion(itemstack);
+@@ -110,7 +115,7 @@ public class ThrownPotion extends ThrowableItemProjectile implements ItemSupplie
+                 if (this.isLingering()) {
+                     this.makeAreaOfEffectCloud(itemstack, potionregistry);
+                 } else {
+-                    this.applySplash(list, hitResult.getType() == HitResult.Type.ENTITY ? ((EntityHitResult) hitResult).getEntity() : null);
++                    this.applySplash(list, hitResult != null && hitResult.getType() == HitResult.Type.ENTITY ? ((EntityHitResult) hitResult).getEntity() : null); // Paper - nullable hitResult
+                 }
+             }
+ 
+diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftFirework.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftFirework.java
+index c242f654c88ca1773429348939d3bb2ffae3768c..d1c7ab67cba881d96b7a5e9220130d86d0514304 100644
+--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftFirework.java
++++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftFirework.java
+@@ -16,24 +16,26 @@ import org.bukkit.inventory.meta.FireworkMeta;
+ public class CraftFirework extends CraftProjectile implements Firework {
+ 
+     private final Random random = new Random();
+-    private final CraftItemStack item;
++    //private CraftItemStack item; // Paper - Remove usage, not accurate representation of current item.
+ 
+     public CraftFirework(CraftServer server, FireworkRocketEntity entity) {
+         super(server, entity);
+ 
+-        ItemStack item = this.getHandle().getEntityData().get(FireworkRocketEntity.DATA_ID_FIREWORKS_ITEM);
+-
+-        if (item.isEmpty()) {
+-            item = new ItemStack(Items.FIREWORK_ROCKET);
+-            this.getHandle().getEntityData().set(FireworkRocketEntity.DATA_ID_FIREWORKS_ITEM, item);
+-        }
+-
+-        this.item = CraftItemStack.asCraftMirror(item);
+-
+-        // Ensure the item is a firework...
+-        if (this.item.getType() != Material.FIREWORK_ROCKET) {
+-            this.item.setType(Material.FIREWORK_ROCKET);
+-        }
++//        Paper Start - Expose firework item directly
++//        ItemStack item = this.getHandle().getEntityData().get(FireworkRocketEntity.DATA_ID_FIREWORKS_ITEM);
++//
++//        if (item.isEmpty()) {
++//            item = new ItemStack(Items.FIREWORK_ROCKET);
++//            this.getHandle().getEntityData().set(FireworkRocketEntity.DATA_ID_FIREWORKS_ITEM, item);
++//        }
++//
++//        this.item = CraftItemStack.asCraftMirror(item);
++//
++//        // Ensure the item is a firework...
++//        if (this.item.getType() != Material.FIREWORK_ROCKET) {
++//            this.item.setType(Material.FIREWORK_ROCKET);
++//        }
++        // Paper End - Expose firework item directly
+     }
+ 
+     @Override
+@@ -53,12 +55,12 @@ public class CraftFirework extends CraftProjectile implements Firework {
+ 
+     @Override
+     public FireworkMeta getFireworkMeta() {
+-        return (FireworkMeta) this.item.getItemMeta();
++        return (FireworkMeta) CraftItemStack.getItemMeta(this.getHandle().getEntityData().get(FireworkRocketEntity.DATA_ID_FIREWORKS_ITEM), Material.FIREWORK_ROCKET); // Paper - Expose firework item directly
+     }
+ 
+     @Override
+     public void setFireworkMeta(FireworkMeta meta) {
+-        this.item.setItemMeta(meta);
++        applyFireworkEffect(meta); // Paper - Expose firework item directly
+ 
+         // Copied from EntityFireworks constructor, update firework lifetime/power
+         this.getHandle().lifetime = 10 * (1 + meta.getPower()) + this.random.nextInt(6) + this.random.nextInt(7);
+@@ -142,4 +144,46 @@ public class CraftFirework extends CraftProjectile implements Firework {
+         return getHandle().spawningEntity;
+     }
+     // Paper end
++    // Paper start - Expose firework item directly + manually setting flight
++    @Override
++    public org.bukkit.inventory.ItemStack getItem() {
++        return CraftItemStack.asBukkitCopy(this.getHandle().getItem());
++    }
++
++    @Override
++    public void setItem(org.bukkit.inventory.ItemStack itemStack) {
++        FireworkMeta meta = getFireworkMeta();
++        ItemStack nmsItem = itemStack == null ? ItemStack.EMPTY : CraftItemStack.asNMSCopy(itemStack);
++        this.getHandle().getEntityData().set(FireworkRocketEntity.DATA_ID_FIREWORKS_ITEM, nmsItem);
++
++        applyFireworkEffect(meta);
++    }
++
++    @Override
++    public int getTicksFlown() {
++        return this.getHandle().life;
++    }
++
++    @Override
++    public void setTicksFlown(int ticks) {
++        this.getHandle().life = ticks;
++    }
++
++    @Override
++    public int getTicksToDetonate() {
++        return this.getHandle().lifetime;
++    }
++
++    @Override
++    public void setTicksToDetonate(int ticks) {
++        this.getHandle().lifetime = ticks;
++    }
++
++    void applyFireworkEffect(FireworkMeta meta) {
++        ItemStack item = this.getHandle().getItem();
++        CraftItemStack.applyMetaToItem(item, meta);
++
++        this.getHandle().getEntityData().set(FireworkRocketEntity.DATA_ID_FIREWORKS_ITEM, item);
++    }
++    // Paper end - Expose firework item directly + manually setting flight
+ }
+diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftFishHook.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftFishHook.java
+index 6bfa984781a483d048ef4318761203c701d8a632..5e0c2c5094e1578162d1a50d50701fbd25e6d961 100644
+--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftFishHook.java
++++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftFishHook.java
+@@ -119,4 +119,15 @@ public class CraftFishHook extends CraftProjectile implements FishHook {
+     public HookState getState() {
+         return HookState.values()[this.getHandle().currentState.ordinal()];
+     }
++    // Paper start - More FishHook API
++    @Override
++    public int getWaitTime() {
++        return this.getHandle().timeUntilLured;
++    }
++
++    @Override
++    public void setWaitTime(int ticks) {
++        this.getHandle().timeUntilLured = ticks;
++    }
++    // Paper end
+ }
+diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftThrownPotion.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftThrownPotion.java
+index 0db8aa840ea026d48215ac5dc80ffde5f12725b1..397e0df15a0e64e5bc522f62f3b327a5039ec4c8 100644
+--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftThrownPotion.java
++++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftThrownPotion.java
+@@ -39,11 +39,31 @@ public class CraftThrownPotion extends CraftThrowableProjectile implements Throw
+         Validate.notNull(item, "ItemStack cannot be null.");
+ 
+         // The ItemStack must be a potion.
+-        Validate.isTrue(item.getType() == Material.LINGERING_POTION || item.getType() == Material.SPLASH_POTION, "ItemStack must be a lingering or splash potion. This item stack was " + item.getType() + ".");
++        //Validate.isTrue(item.getType() == Material.LINGERING_POTION || item.getType() == Material.SPLASH_POTION, "ItemStack must be a lingering or splash potion. This item stack was " + item.getType() + "."); // Paper - Projectile API
++        org.bukkit.inventory.meta.PotionMeta meta = (item.getType() == Material.LINGERING_POTION || item.getType() == Material.SPLASH_POTION) ? null : this.getPotionMeta(); // Paper - Projectile API
+ 
+         this.getHandle().setItem(CraftItemStack.asNMSCopy(item));
++        if (meta != null) this.setPotionMeta(meta); // Paper - Projectile API
+     }
+ 
++    // Paper start - Projectile API
++    @Override
++    public org.bukkit.inventory.meta.PotionMeta getPotionMeta() {
++        return (org.bukkit.inventory.meta.PotionMeta) CraftItemStack.getItemMeta(this.getHandle().getItemRaw(), Material.SPLASH_POTION);
++    }
++
++    @Override
++    public void setPotionMeta(org.bukkit.inventory.meta.PotionMeta meta) {
++        net.minecraft.world.item.ItemStack item = this.getHandle().getItem();
++        CraftItemStack.applyMetaToItem(item, meta);
++        this.getHandle().setItem(item); // Reset item
++    }
++
++    @Override
++    public void splash() {
++        this.getHandle().splash(null);
++    }
++    // Paper end
+     @Override
+     public net.minecraft.world.entity.projectile.ThrownPotion getHandle() {
+         return (net.minecraft.world.entity.projectile.ThrownPotion) entity;
+diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
+index f3abcd5949011eaef3d1ba68f4cc0751042d2834..bfb1ad0b6e20e10fee53f94a3e6c4f8aad7aae7d 100644
+--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
++++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftItemStack.java
+@@ -278,12 +278,20 @@ public final class CraftItemStack extends ItemStack {
+     public ItemMeta getItemMeta() {
+         return CraftItemStack.getItemMeta(this.handle);
+     }
++    // Paper start
++    public static void applyMetaToItem(net.minecraft.world.item.ItemStack itemStack, ItemMeta meta) {
++        ((org.bukkit.craftbukkit.inventory.CraftMetaItem) meta).applyToItem(itemStack.getOrCreateTag());
++    }
+ 
+     public static ItemMeta getItemMeta(net.minecraft.world.item.ItemStack item) {
++        return getItemMeta(item, CraftItemStack.getType(item));
++    }
++    public static ItemMeta getItemMeta(net.minecraft.world.item.ItemStack item, Material material) {
++        // Paper end
+         if (!CraftItemStack.hasItemMeta(item)) {
+-            return CraftItemFactory.instance().getItemMeta(CraftItemStack.getType(item));
++            return CraftItemFactory.instance().getItemMeta(material); // Paper
+         }
+-        switch (CraftItemStack.getType(item)) {
++        switch (material) {  // Paper
+             case WRITTEN_BOOK:
+                 return new CraftMetaBookSigned(item.getTag());
+             case WRITABLE_BOOK: