From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jason Penilla <11360596+jpenilla@users.noreply.github.com>
Date: Fri, 13 Sep 2024 14:32:32 -0700
Subject: [PATCH] Paper PR: Add ticket on player join to avoid chunk
 load-unload-load cycle

Original license: GPLv3
Original project: https://github.com/PaperMC/Paper
Paper pull request: https://github.com/PaperMC/Paper/pull/11398

Adding the entity will add and then immediately remove an entity load ticket, which would result in the chunk loading and then unloading before being loaded again once the player chunk loader reacts (delay can vary based on rate limit configs)
By adding a ticket with a short removal delay we attempt to keep the chunk loaded until the player chunk loader reacts, but this is not a guarantee due to the aforementioned rate limit configs. Plugins should still handle load/unload events as normal, however this will reduce redundant calls.
The delay is currently set to 2 seconds, however, we may want to adjust this before merging (for example the player chunk unload delay is 5 seconds)

fixes Paper#9581

diff --git a/ca/spottedleaf/moonrise/patches/chunk_system/player/RegionizedPlayerChunkLoader.java b/ca/spottedleaf/moonrise/patches/chunk_system/player/RegionizedPlayerChunkLoader.java
index 19b5e4856d471ebfa49335ed19ced767e57df771..9454a71d396128d3c55a0ba550d955af6237f9e4 100644
--- a/ca/spottedleaf/moonrise/patches/chunk_system/player/RegionizedPlayerChunkLoader.java
+++ b/ca/spottedleaf/moonrise/patches/chunk_system/player/RegionizedPlayerChunkLoader.java
@@ -48,6 +48,7 @@ public final class RegionizedPlayerChunkLoader {
 
     public static final TicketType PLAYER_TICKET         = ChunkSystemTicketType.create("chunk_system:player_ticket", Long::compareTo);
     public static final TicketType PLAYER_TICKET_DELAYED = ChunkSystemTicketType.create("chunk_system:player_ticket_delayed", Long::compareTo, 1L);
+    public static final TicketType PLAYER_JOIN           = ChunkSystemTicketType.create("chunk_system:player_join", (a, b) -> 0, 5 * 20); // Paper PR - Add ticket on player join to avoid chunk load-unload-load cycle
 
     public static final int GENERATED_TICKET_LEVEL = ChunkHolderManager.FULL_LOADED_TICKET_LEVEL;
     public static final int LOADED_TICKET_LEVEL = ChunkTaskScheduler.getTicketLevel(ChunkStatus.EMPTY);
diff --git a/net/minecraft/server/players/PlayerList.java b/net/minecraft/server/players/PlayerList.java
index 52e5a87ed1e425b74f7428798bf0f0564f6747ae..76e7133c580725635d517bc8dd20aa10210133aa 100644
--- a/net/minecraft/server/players/PlayerList.java
+++ b/net/minecraft/server/players/PlayerList.java
@@ -441,6 +441,13 @@ public abstract class PlayerList {
             // this.broadcastAll(ClientboundPlayerInfoUpdatePacket.createPlayerInitializing(List.of(player))); // CraftBukkit - replaced with loop below
             // Paper start - Fire PlayerJoinEvent when Player is actually ready; correctly register player BEFORE PlayerJoinEvent, so the entity is valid and doesn't require tick delay hacks
             player.supressTrackerForLogin = true;
+        // Paper PR start - Add ticket on player join to avoid chunk load-unload-load cycle
+        serverLevel.moonrise$getChunkTaskScheduler().chunkHolderManager.addTicketAtLevel(
+            ca.spottedleaf.moonrise.patches.chunk_system.player.RegionizedPlayerChunkLoader.PLAYER_JOIN,
+            player.chunkPosition(),
+            ca.spottedleaf.moonrise.patches.chunk_system.player.RegionizedPlayerChunkLoader.TICK_TICKET_LEVEL,
+            net.minecraft.util.Unit.INSTANCE);
+        // Paper PR end - Add ticket on player join to avoid chunk load-unload-load cycle
             serverLevel.addNewPlayer(player);
             this.server.getCustomBossEvents().onPlayerConnect(player); // see commented out section below serverLevel.addPlayerJoin(player);
             // Paper end - Fire PlayerJoinEvent when Player is actually ready