Paper/patches/server/0421-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 882801984304b8570669bc0ff9388fbfc3846dcf..aa8b58a51792b1e4e6d18e13f06f697e3e2ebe72 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
@@ -384,7 +384,7 @@ 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();
 
@@ -937,7 +937,7 @@ 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;
         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 40a3a1e0bfb8c274b8de56d1ac3edca6c170296c..53d4f1687527f383841ecc35ffc16d8bf8eefb78 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
@@ -279,7 +279,13 @@ 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);
     }
 
@@ -293,6 +299,12 @@ 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");
@@ -358,7 +370,7 @@ 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;
@@ -439,9 +451,12 @@ public class CraftWorld extends CraftRegionAccessor implements World {
         org.spigotmc.AsyncCatcher.catchOp("chunk load"); // Spigot
         // Paper start - Optimize this method
         ChunkPos chunkPos = new ChunkPos(x, z);
+        ChunkAccess immediate = world.getChunkSource().getChunkAtIfLoadedImmediately(x, z); // Paper
+        if (immediate != null) return true; // Paper
 
         if (!generate) {
-            ChunkAccess immediate = world.getChunkSource().getChunkAtImmediately(x, z);
+
+            //IChunkAccess immediate = world.getChunkProvider().getChunkAtImmediately(x, z); // Paper
             if (immediate == null) {
                 immediate = world.getChunkSource().chunkMap.getUnloadingChunk(x, z);
             }
@@ -449,7 +464,7 @@ public class CraftWorld extends CraftRegionAccessor implements World {
                 if (!(immediate instanceof ImposterProtoChunk) && !(immediate instanceof net.minecraft.world.level.chunk.LevelChunk)) {
                     return false; // not full status
                 }
-                world.getChunkSource().addRegionTicket(TicketType.PLUGIN, chunkPos, 1, Unit.INSTANCE);
+                world.getChunkSource().addRegionTicket(TicketType.PLUGIN, chunkPos, 0, Unit.INSTANCE); // Paper
                 world.getChunk(x, z); // make sure we're at ticket level 32 or lower
                 return true;
             }
@@ -475,7 +490,7 @@ public class CraftWorld extends CraftRegionAccessor implements World {
             // we do this so we do not re-read the chunk data on disk
         }
 
-        world.getChunkSource().addRegionTicket(TicketType.PLUGIN, chunkPos, 1, Unit.INSTANCE);
+        world.getChunkSource().addRegionTicket(TicketType.PLUGIN, chunkPos, 0, Unit.INSTANCE); // Paper
         world.getChunkSource().getChunk(x, z, ChunkStatus.FULL, true);
         return true;
         // Paper end
@@ -2203,6 +2218,7 @@ 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));
             });
         });