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, 112 insertions, 0 deletions

diff --git a/patches/removed/1.19.2-legacy-chunksystem/0048-Per-Player-View-Distance-API-placeholders.patch b/patches/removed/1.19.2-legacy-chunksystem/0048-Per-Player-View-Distance-API-placeholders.patch
new file mode 100644
index 0000000000..05d14292f2
--- /dev/null
+++ b/patches/removed/1.19.2-legacy-chunksystem/0048-Per-Player-View-Distance-API-placeholders.patch
@@ -0,0 +1,112 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Zach Brown <[email protected]>
+Date: Mon, 6 May 2019 01:29:25 -0400
+Subject: [PATCH] Per-Player View Distance API placeholders
+
+I hope to look at this more in-depth soon. It appears doable.
+However this should not block the update.
+
+diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
+index db7e2207612b56b0869a947edd03a6d3f9209e22..981e60c7bf2eee52e84f9894ff689631388a7715 100644
+--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
++++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
+@@ -2253,4 +2253,6 @@ public class ServerPlayer extends Player {
+         return (CraftPlayer) super.getBukkitEntity();
+     }
+     // CraftBukkit end
++
++    public final int getViewDistance() { return this.getLevel().getChunkSource().chunkMap.viewDistance - 1; } // Paper - placeholder
+ }
+diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+index 9a6820b10e4164cc38d269853b5c2a49175cb890..0ed46cdd443ac42a7d57ee59f6f04fd9e9259c16 100644
+--- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
++++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+@@ -1913,6 +1913,37 @@ public class CraftWorld extends CraftRegionAccessor implements World {
+         return world.spigotConfig.simulationDistance;
+     }
+     // Spigot end
++    // Paper start - view distance api
++    @Override
++    public void setViewDistance(int viewDistance) {
++        throw new UnsupportedOperationException(); //TODO
++    }
++
++    @Override
++    public void setSimulationDistance(int simulationDistance) {
++        throw new UnsupportedOperationException(); //TODO
++    }
++
++    @Override
++    public int getNoTickViewDistance() {
++        throw new UnsupportedOperationException(); //TODO
++    }
++
++    @Override
++    public void setNoTickViewDistance(int viewDistance) {
++        throw new UnsupportedOperationException(); //TODO
++    }
++
++    @Override
++    public int getSendViewDistance() {
++        throw new UnsupportedOperationException(); //TODO
++    }
++
++    @Override
++    public void setSendViewDistance(int viewDistance) {
++        throw new UnsupportedOperationException(); //TODO
++    }
++    // Paper end - view distance api
+ 
+     // Spigot start
+     private final org.bukkit.World.Spigot spigot = new org.bukkit.World.Spigot()
+diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+index 9d2506a042b49089094be79b5d0ed54f088b9625..f2ada37115392466edbed8a2d331084aaaf7b774 100644
+--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
++++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+@@ -408,6 +408,46 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
+             connection.disconnect(message == null ? net.kyori.adventure.text.Component.empty() : message);
+         }
+     }
++
++    @Override
++    public int getViewDistance() {
++        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
++    }
++
++    @Override
++    public void setViewDistance(int viewDistance) {
++        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
++    }
++
++    @Override
++    public int getSimulationDistance() {
++        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
++    }
++
++    @Override
++    public void setSimulationDistance(int simulationDistance) {
++        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
++    }
++
++    @Override
++    public int getNoTickViewDistance() {
++        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
++    }
++
++    @Override
++    public void setNoTickViewDistance(int viewDistance) {
++        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
++    }
++
++    @Override
++    public int getSendViewDistance() {
++        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
++    }
++
++    @Override
++    public void setSendViewDistance(int viewDistance) {
++        throw new UnsupportedOperationException("Per-Player View Distance APIs need further understanding to properly implement (There are per world view distances though!)"); // TODO
++    }
+     // Paper end
+ 
+     @Override