Avoid quadratic behavior in item frames updating player pins on maps

Author: 2No2Name

common/src/main/java/net/caffeinemc/mods/lithium/mixin/entity/framed_maps/MapItemSavedDataMixin.java

@@ -0,0 +1,42 @@
+package net.caffeinemc.mods.lithium.mixin.entity.framed_maps;
+
+import com.llamalad7.mixinextras.injector.wrapoperation.Operation;
+import com.llamalad7.mixinextras.injector.wrapoperation.WrapOperation;
+import com.llamalad7.mixinextras.sugar.Local;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.level.saveddata.SavedData;
+import net.minecraft.world.level.saveddata.maps.MapItemSavedData;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+
+@Mixin(MapItemSavedData.class)
+public abstract class MapItemSavedDataMixin extends SavedData {
+
+    @Shadow
+    @Final
+    private Map<Player, MapItemSavedData.HoldingPlayer> carriedByPlayers;
+
+    @WrapOperation(
+            method = "tickCarriedBy(Lnet/minecraft/world/entity/player/Player;Lnet/minecraft/world/item/ItemStack;)V",
+            at = @At(value = "INVOKE", target = "Ljava/util/List;size()I")
+    )
+    private int sizeOrOne(List<MapItemSavedData.HoldingPlayer> instance, Operation<Integer> original, @Local(argsOnly = true) ItemStack mapStack) {
+        return mapStack.isFramed() ? 1 : original.call(instance);
+    }
+
+    @WrapOperation(
+            method = "tickCarriedBy(Lnet/minecraft/world/entity/player/Player;Lnet/minecraft/world/item/ItemStack;)V",
+            at = @At(value = "INVOKE", target = "Ljava/util/List;get(I)Ljava/lang/Object;")
+    )
+    private <E> E getOrGetThePlayer(List<E> instance, int i, Operation<E> original, @Local(argsOnly = true) Player player, @Local(argsOnly = true) ItemStack mapStack) {
+        //noinspection unchecked
+        return mapStack.isFramed() ? (E) Objects.requireNonNull(this.carriedByPlayers.get(player)) : original.call(instance, i);
+    }
+}

common/src/main/java/net/caffeinemc/mods/lithium/mixin/entity/framed_maps/package-info.java

@@ -0,0 +1,4 @@
+@MixinConfigOption(description = "Avoid map items in item frames performing inventory scanning quadratic in the number of online players. Instead, scan each player inventory once per map item in item frame only.")
+package net.caffeinemc.mods.lithium.mixin.entity.framed_maps;
+
+import net.caffeinemc.gradle.MixinConfigOption;

common/src/main/resources/lithium.mixins.json

@@ -125,6 +125,7 @@
     "entity.fast_hand_swing.LivingEntityMixin",
     "entity.fast_powder_snow_check.LivingEntityMixin",
     "entity.fast_retrieval.EntitySectionStorageMixin",
+    "entity.framed_maps.MapItemSavedDataMixin",
     "entity.inactive_navigations.HappyGhastMixin",
     "entity.inactive_navigations.LivingEntityMixin",
     "entity.inactive_navigations.MobMixin",

lithium-fabric-mixin-config.md

@@ -336,6 +336,10 @@ Skip checking whether an entity is inside powder snow for movement speed slowdow
 (default: `true`)  
 Access entities faster when accessing a relatively small number of entity sections
 
+### `mixin.entity.framed_maps`
+(default: `true`)  
+Avoid map items in item frames performing inventory scanning quadratic in the number of online players. Instead, scan each player inventory once per map item in item frame only.
+  
 ### `mixin.entity.inactive_navigations`
 (default: `true`)  
 Block updates skip notifying mobs that won't react to the block update anyways  

lithium-neoforge-mixin-config.md

@@ -323,6 +323,10 @@ Skip checking whether an entity is inside powder snow for movement speed slowdow
 (default: `true`)  
 Access entities faster when accessing a relatively small number of entity sections
 
+### `mixin.entity.framed_maps`
+(default: `true`)  
+Avoid map items in item frames performing inventory scanning quadratic in the number of online players. Instead, scan each player inventory once per map item in item frame only.
+  
 ### `mixin.entity.inactive_navigations`
 (default: `true`)  
 Block updates skip notifying mobs that won't react to the block update anyways