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 7803075383cdde77444991e72f49ed67627f95ed..936928dda8b09386ef936cec9da65eb76b1ccf1d 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
@@ -377,7 +377,7 @@ public final class CraftServer implements Server {
         this.overrideSpawnLimits();
         console.autosavePeriod = this.configuration.getInt("ticks-per.autosave");
         this.warningState = WarningState.value(this.configuration.getString("settings.deprecated-verbose"));
-        TicketType.PLUGIN.timeout = this.configuration.getInt("chunk-gc.period-in-ticks");
+        TicketType.PLUGIN.timeout = Math.min(20, this.configuration.getInt("chunk-gc.period-in-ticks")); // Paper - cap plugin loads to 1 second
         this.minimumAPI = this.configuration.getString("settings.minimum-api");
         this.loadIcon();
 
@@ -935,7 +935,7 @@ public final class CraftServer implements Server {
         this.console.setMotd(config.motd);
         this.overrideSpawnLimits();
         this.warningState = WarningState.value(this.configuration.getString("settings.deprecated-verbose"));
-        TicketType.PLUGIN.timeout = this.configuration.getInt("chunk-gc.period-in-ticks");
+        TicketType.PLUGIN.timeout = Math.min(20, configuration.getInt("chunk-gc.period-in-ticks")); // Paper - cap plugin loads to 1 second
         this.minimumAPI = this.configuration.getString("settings.minimum-api");
         this.printSaveWarning = false;
         this.console.autosavePeriod = this.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 c44cfa0dd5794976c74211467ac0b7022cce17e9..6070409175b106ba6920adf4fa860215cd6f3087 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
@@ -282,7 +282,13 @@ public class CraftWorld extends CraftRegionAccessor implements World {
 
     @Override
     public Chunk getChunkAt(int x, int z) {
-        net.minecraft.world.level.chunk.LevelChunk chunk = (net.minecraft.world.level.chunk.LevelChunk) this.world.getChunk(x, z, ChunkStatus.FULL, true);
+        // Paper start - add ticket to hold chunk for a little while longer if plugin accesses it
+        net.minecraft.world.level.chunk.LevelChunk chunk = this.world.getChunkSource().getChunkAtIfLoadedImmediately(x, z);
+        if (chunk == null) {
+            this.addTicket(x, z);
+            chunk = this.world.getChunkSource().getChunk(x, z, true);
+        }
+        // Paper end
         return new CraftChunk(chunk);
     }
 
@@ -296,6 +302,12 @@ public class CraftWorld extends CraftRegionAccessor implements World {
         return new CraftChunk(this.getHandle(), x, z);
     }
 
+    // Paper start
+    private void addTicket(int x, int z) {
+        io.papermc.paper.util.MCUtil.MAIN_EXECUTOR.execute(() -> this.world.getChunkSource().addRegionTicket(TicketType.PLUGIN, new ChunkPos(x, z), 0, Unit.INSTANCE)); // Paper
+    }
+    // Paper end
+
     @Override
     public Chunk getChunkAt(Block block) {
         Preconditions.checkArgument(block != null, "null block");
@@ -347,7 +359,7 @@ public class CraftWorld extends CraftRegionAccessor implements World {
     public boolean unloadChunkRequest(int x, int z) {
         org.spigotmc.AsyncCatcher.catchOp("chunk unload"); // Spigot
         if (this.isChunkLoaded(x, z)) {
-            this.world.getChunkSource().removeRegionTicket(TicketType.PLUGIN, new ChunkPos(x, z), 1, Unit.INSTANCE);
+            this.world.getChunkSource().removeRegionTicket(TicketType.PLUGIN, new ChunkPos(x, z), 0, Unit.INSTANCE); // Paper
         }
 
         return true;
@@ -432,7 +444,7 @@ public class CraftWorld extends CraftRegionAccessor implements World {
         }
 
         if (chunk instanceof net.minecraft.world.level.chunk.LevelChunk) {
-            this.world.getChunkSource().addRegionTicket(TicketType.PLUGIN, new ChunkPos(x, z), 1, Unit.INSTANCE);
+            this.world.getChunkSource().addRegionTicket(TicketType.PLUGIN, new ChunkPos(x, z), 0, Unit.INSTANCE); // Paper
             return true;
         }
 
@@ -2184,6 +2196,7 @@ public class CraftWorld extends CraftRegionAccessor implements World {
         io.papermc.paper.chunk.system.ChunkSystem.scheduleChunkLoad(this.getHandle(), x, z, gen, ChunkStatus.FULL, true, priority, (c) -> {
             net.minecraft.server.MinecraftServer.getServer().scheduleOnMain(() -> {
                 net.minecraft.world.level.chunk.LevelChunk chunk = (net.minecraft.world.level.chunk.LevelChunk)c;
+                if (chunk != null) this.addTicket(x, z); // Paper
                 ret.complete(chunk == null ? null : new CraftChunk(chunk));
             });
         });