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, 61 insertions, 0 deletions

diff --git a/patches/server/0584-fix-converting-txt-to-json-file.patch b/patches/server/0584-fix-converting-txt-to-json-file.patch
new file mode 100644
index 0000000000..f43088ff63
--- /dev/null
+++ b/patches/server/0584-fix-converting-txt-to-json-file.patch
@@ -0,0 +1,61 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Jake Potrebic <[email protected]>
+Date: Mon, 4 Jan 2021 19:49:15 -0800
+Subject: [PATCH] fix converting txt to json file
+
+
+diff --git a/src/main/java/net/minecraft/server/dedicated/DedicatedPlayerList.java b/src/main/java/net/minecraft/server/dedicated/DedicatedPlayerList.java
+index d83bed436d2ad51cef83ecbf0c7df227a67ff404..dc96b30c70cd79d7b2a0322f32b9399a0f2faa41 100644
+--- a/src/main/java/net/minecraft/server/dedicated/DedicatedPlayerList.java
++++ b/src/main/java/net/minecraft/server/dedicated/DedicatedPlayerList.java
+@@ -17,6 +17,11 @@ public class DedicatedPlayerList extends PlayerList {
+         this.setViewDistance(dedicatedServerProperties.viewDistance);
+         this.setSimulationDistance(dedicatedServerProperties.simulationDistance);
+         super.setUsingWhiteList(dedicatedServerProperties.whiteList.get());
++        // Paper start - moved from constructor
++    }
++    @Override
++    public void loadAndSaveFiles() {
++        // Paper end
+         this.loadUserBanList();
+         this.saveUserBanList();
+         this.loadIpBanList();
+diff --git a/src/main/java/net/minecraft/server/dedicated/DedicatedServer.java b/src/main/java/net/minecraft/server/dedicated/DedicatedServer.java
+index 8984a30f0fa790e7854534076912e619f9487160..f4378558557c36cdbbaf43481b679f86583bdf16 100644
+--- a/src/main/java/net/minecraft/server/dedicated/DedicatedServer.java
++++ b/src/main/java/net/minecraft/server/dedicated/DedicatedServer.java
+@@ -203,6 +203,12 @@ public class DedicatedServer extends MinecraftServer implements ServerInterface
+         io.papermc.paper.util.ObfHelper.INSTANCE.getClass(); // Paper - load mappings for stacktrace deobf and etc.
+         paperConfigurations.initializeGlobalConfiguration();
+         paperConfigurations.initializeWorldDefaultsConfiguration();
++        // Paper start - moved up to right after PlayerList creation but before file load/save
++        if (this.convertOldUsers()) {
++            this.getProfileCache().save(false); // Paper
++        }
++        this.getPlayerList().loadAndSaveFiles(); // Must be after convertNames
++        // Paper end - moved up
+         org.spigotmc.WatchdogThread.doStart(org.spigotmc.SpigotConfig.timeoutTime, org.spigotmc.SpigotConfig.restartOnCrash);
+         io.papermc.paper.command.PaperCommands.registerCommands(this);
+         com.destroystokyo.paper.Metrics.PaperMetrics.startMetrics();
+@@ -258,9 +264,6 @@ public class DedicatedServer extends MinecraftServer implements ServerInterface
+             DedicatedServer.LOGGER.warn("To change this, set \"online-mode\" to \"true\" in the server.properties file.");
+         }
+ 
+-        if (this.convertOldUsers()) {
+-            this.getProfileCache().save(false); // Paper
+-        }
+ 
+         if (!OldUsersConverter.serverReadyAfterUserconversion(this)) {
+             return false;
+diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
+index a199dee07c67e4e66bbdccd2c5f77223cbc6fecf..78d0ece91358766aa03b833234b8cb9466371565 100644
+--- a/src/main/java/net/minecraft/server/players/PlayerList.java
++++ b/src/main/java/net/minecraft/server/players/PlayerList.java
+@@ -177,6 +177,7 @@ public abstract class PlayerList {
+         this.maxPlayers = maxPlayers;
+         this.playerIo = saveHandler;
+     }
++    abstract public void loadAndSaveFiles(); // Paper - moved from DedicatedPlayerList constructor
+ 
+     public void placeNewPlayer(Connection connection, ServerPlayer player) {
+         player.isRealPlayer = true; // Paper