Paper/Spigot-Server-Patches/0495-Add-Plugin-Tickets-to-API-Chunk-Methods.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Tue, 9 Jun 2020 03:33:03 -0400
Subject: [PATCH] Add Plugin Tickets to API Chunk Methods

Like previous versions, plugins loading chunks kept them loaded until
they garbage collected to avoid constant spamming of chunk loads

This adds tickets to a few more places so that they can be unloaded.

Additionally, this drops their ticket level to BORDER so they wont be ticking
so they will just sit inactive instead.

Using .loadChunk to keep a chunk ticking was a horrible idea for upstream
when we have TWO methods that are able to do that already in the API.

Also reduce their collection count down to a maximum of 1 second. Barely
anyone knows what chunk-gc is in bukkit.yml as its less relevant now, and
since this wasn't spigot behavior, this is safe to mostly ignore (unless someone
wants it to collect even faster, they can restore that setting back to 1 instead of 20+)

Not adding it to .getType() though to keep behavior consistent with vanilla for performance reasons.

diff --git a/src/main/java/org/bukkit/craftbukkit/CraftServer.java b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
index 8c454db0986fe5c23f7b8ece0abdad1f1e36cf08..94c91b38ec71a03fc3bc5b1e15f9737cb0e8d1a8 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
@@ -346,7 +346,7 @@ public final class CraftServer implements Server {
         ambientSpawn = configuration.getInt("spawn-limits.ambient");
         console.autosavePeriod = configuration.getInt("ticks-per.autosave");
         warningState = WarningState.value(configuration.getString("settings.deprecated-verbose"));
-        TicketType.PLUGIN.loadPeriod = configuration.getInt("chunk-gc.period-in-ticks");
+        TicketType.PLUGIN.loadPeriod = Math.min(20, configuration.getInt("chunk-gc.period-in-ticks")); // Paper - cap plugin loads to 1 second
         minimumAPI = configuration.getString("settings.minimum-api");
         loadIcon();
     }
@@ -834,7 +834,7 @@ public final class CraftServer implements Server {
         waterAmbientSpawn = configuration.getInt("spawn-limits.water-ambient");
         ambientSpawn = configuration.getInt("spawn-limits.ambient");
         warningState = WarningState.value(configuration.getString("settings.deprecated-verbose"));
-        TicketType.PLUGIN.loadPeriod = configuration.getInt("chunk-gc.period-in-ticks");
+        TicketType.PLUGIN.loadPeriod = Math.min(20, configuration.getInt("chunk-gc.period-in-ticks")); // Paper - cap plugin loads to 1 second
         minimumAPI = configuration.getString("settings.minimum-api");
         printSaveWarning = false;
         console.autosavePeriod = configuration.getInt("ticks-per.autosave");
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
index 560590c3c772eb91d562c622b627af36bf394609..10697f8b5208a72bf3d7248c5abd73ddd10420cd 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
@@ -407,9 +407,22 @@ public class CraftWorld implements World {
 
     @Override
     public Chunk getChunkAt(int x, int z) {
-        return this.world.getChunkProvider().getChunkAt(x, z, true).bukkitChunk;
+        // Paper start - add ticket to hold chunk for a little while longer if plugin accesses it
+        net.minecraft.server.Chunk chunk = world.getChunkProvider().getChunkAtIfLoadedImmediately(x, z);
+        if (chunk == null) {
+            addTicket(x, z);
+            chunk = this.world.getChunkProvider().getChunkAt(x, z, true);
+        }
+        return chunk.bukkitChunk;
+        // Paper end
     }
 
+    // Paper start
+    private void addTicket(int x, int z) {
+        MCUtil.MAIN_EXECUTOR.execute(() -> world.getChunkProvider().addTicket(TicketType.PLUGIN, new ChunkCoordIntPair(x, z), 0, Unit.INSTANCE)); // Paper
+    }
+    // Paper end
+
     @Override
     public Chunk getChunkAt(Block block) {
         Preconditions.checkArgument(block != null, "null block");
@@ -483,7 +496,7 @@ public class CraftWorld implements World {
     public boolean unloadChunkRequest(int x, int z) {
         org.spigotmc.AsyncCatcher.catchOp("chunk unload"); // Spigot
         if (isChunkLoaded(x, z)) {
-            world.getChunkProvider().removeTicket(TicketType.PLUGIN, new ChunkCoordIntPair(x, z), 1, Unit.INSTANCE);
+            world.getChunkProvider().removeTicket(TicketType.PLUGIN, new ChunkCoordIntPair(x, z), 0, Unit.INSTANCE); // Paper
         }
 
         return true;
@@ -560,10 +573,12 @@ public class CraftWorld implements World {
         org.spigotmc.AsyncCatcher.catchOp("chunk load"); // Spigot
         // Paper start - Optimize this method
         ChunkCoordIntPair chunkPos = new ChunkCoordIntPair(x, z);
+        IChunkAccess immediate = world.getChunkProvider().getChunkAtIfLoadedImmediately(x, z); // Paper
+        if (immediate != null) return true; // Paper
 
         if (!generate) {
 
-            IChunkAccess immediate = world.getChunkProvider().getChunkAtImmediately(x, z);
+            //IChunkAccess immediate = world.getChunkProvider().getChunkAtImmediately(x, z); // Paper
             if (immediate == null) {
                 immediate = world.getChunkProvider().playerChunkMap.getUnloadingChunk(x, z);
             }
@@ -571,7 +586,7 @@ public class CraftWorld implements World {
                 if (!(immediate instanceof ProtoChunkExtension) && !(immediate instanceof net.minecraft.server.Chunk)) {
                     return false; // not full status
                 }
-                world.getChunkProvider().addTicket(TicketType.PLUGIN, chunkPos, 1, Unit.INSTANCE);
+                world.getChunkProvider().addTicket(TicketType.PLUGIN, chunkPos, 0, Unit.INSTANCE); // Paper
                 world.getChunkAt(x, z); // make sure we're at ticket level 32 or lower
                 return true;
             }
@@ -598,7 +613,7 @@ public class CraftWorld implements World {
             // we do this so we do not re-read the chunk data on disk
         }
 
-        world.getChunkProvider().addTicket(TicketType.PLUGIN, chunkPos, 1, Unit.INSTANCE);
+        world.getChunkProvider().addTicket(TicketType.PLUGIN, chunkPos, 0, Unit.INSTANCE); // Paper
         world.getChunkProvider().getChunkAt(x, z, ChunkStatus.FULL, true);
         return true;
         // Paper end
@@ -2531,6 +2546,7 @@ public class CraftWorld implements World {
         }
         return this.world.getChunkProvider().getChunkAtAsynchronously(x, z, gen, urgent).thenComposeAsync((either) -> {
             net.minecraft.server.Chunk chunk = (net.minecraft.server.Chunk) either.left().orElse(null);
+            if (chunk != null) addTicket(x, z); // Paper
             return CompletableFuture.completedFuture(chunk == null ? null : chunk.getBukkitChunk());
         }, MinecraftServer.getServer());
     }