From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: MrPowerGamerBR <git@mrpowergamerbr.com>
Date: Mon, 13 Jan 2025 16:41:37 -0300
Subject: [PATCH] Fix MC-117075: TE Unload Lag Spike

We replaced the `blockEntityTickers` list with a custom list based on fastutil's `ObjectArrayList` with a small yet huge change for us: A method that allows us to remove a list of indexes from the list.

This is WAY FASTER than using `removeAll` with a list of entries to be removed, because we don't need to calculate the identity of each block entity to be removed, and we can jump directly to where the search should begin, giving a performance boost for small removals (because we don't need to loop thru the entire list to find what element should be removed) and a performance boost for big removals (no need to calculate the identity of each block entity).

diff --git a/net/minecraft/world/level/Level.java b/net/minecraft/world/level/Level.java
index 27c2ea4a387ee5f7d078a42cb57f146cb748501d..644ab8b2c797f0675530a3efe23a878899689d66 100644
--- a/net/minecraft/world/level/Level.java
+++ b/net/minecraft/world/level/Level.java
@@ -115,7 +115,7 @@ public abstract class Level implements LevelAccessor, AutoCloseable, ca.spottedl
     public static final int TICKS_PER_DAY = 24000;
     public static final int MAX_ENTITY_SPAWN_Y = 20000000;
     public static final int MIN_ENTITY_SPAWN_Y = -20000000;
-    public final List<TickingBlockEntity> blockEntityTickers = Lists.newArrayList(); // Paper - public
+    public final net.sparklypower.sparklypaper.BlockEntityTickersList blockEntityTickers = new net.sparklypower.sparklypaper.BlockEntityTickersList(); // Paper - public // SparklyPaper - optimize block entity removals
     protected final NeighborUpdater neighborUpdater;
     private final List<TickingBlockEntity> pendingBlockEntityTickers = Lists.newArrayList();
     private boolean tickingBlockEntities;
@@ -1479,7 +1479,7 @@ public abstract class Level implements LevelAccessor, AutoCloseable, ca.spottedl
             TickingBlockEntity tickingBlockEntity = this.blockEntityTickers.get(this.tileTickPosition);
             // Spigot end
             if (tickingBlockEntity.isRemoved()) {
-                toRemove.add(tickingBlockEntity); // Paper - Fix MC-117075; use removeAll
+                this.blockEntityTickers.markAsRemoved(this.tileTickPosition); // toRemove.add(tickingBlockEntity); // SparklyPaper - optimize block entity removals // Paper - Fix MC-117075; use removeAll
             } else if (runsNormally && this.shouldTickBlocksAt(tickingBlockEntity.getPos())) {
                 tickingBlockEntity.tick();
                 // Paper start - rewrite chunk system
@@ -1491,6 +1491,7 @@ public abstract class Level implements LevelAccessor, AutoCloseable, ca.spottedl
         }
         this.blockEntityTickers.removeAll(toRemove); // Paper - Fix MC-117075
 
+        this.blockEntityTickers.removeMarkedEntries(); // SparklyPaper - optimize block entity removals
         this.tickingBlockEntities = false;
         profilerFiller.pop();
         this.spigotConfig.currentPrimedTnt = 0; // Spigot