R3944Realms/ModernFix-fix
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Fix race condition when mods create tags on different threads

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embeddedt 2025-07-12 22:22:58 -04:00
parent 6b37051980
commit 873e3bd676
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GPG Key ID: A69433EC199B5613
2 changed files with 79 additions and 0 deletions
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40
common/src/main/java/org/embeddedt/modernfix/common/mixin/bugfix/concurrency/MappedRegistryMixin.java Normal file
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package org.embeddedt.modernfix.common.mixin.bugfix.concurrency;
import net.minecraft.core.HolderSet;
import net.minecraft.core.MappedRegistry;
import net.minecraft.tags.TagKey;
import org.spongepowered.asm.mixin.Mixin;
import org.spongepowered.asm.mixin.Overwrite;
import org.spongepowered.asm.mixin.Shadow;
import java.util.IdentityHashMap;
import java.util.Map;
@Mixin(value = MappedRegistry.class, priority = 500)
public abstract class MappedRegistryMixin<T> {
@Shadow private volatile Map<TagKey<T>, HolderSet.Named<T>> tags;
@Shadow protected abstract HolderSet.Named<T> createTag(TagKey<T> key);
/**
* @author embeddedt (issue found by Uncandango)
* @reason vanilla does not use the correct double-checked locking paradigm, which leads to race conditions
*/
@Overwrite
public HolderSet.Named<T> getOrCreateTag(TagKey<T> key) {
HolderSet.Named<T> named = this.tags.get(key);
if (named == null) {
// synchronize and check again - this is the bugfix
synchronized (this) {
named = this.tags.get(key);
if (named == null) {
named = this.createTag(key);
Map<TagKey<T>, HolderSet.Named<T>> map = new IdentityHashMap<>(this.tags);
map.put(key, named);
this.tags = map;
}
}
}
return named;
}
}

39
forge/src/main/java/org/embeddedt/modernfix/forge/mixin/bugfix/concurrency/NamespacedWrapperMixin.java Normal file
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package org.embeddedt.modernfix.forge.mixin.bugfix.concurrency;
import net.minecraft.core.HolderSet;
import net.minecraft.tags.TagKey;
import org.spongepowered.asm.mixin.Mixin;
import org.spongepowered.asm.mixin.Overwrite;
import org.spongepowered.asm.mixin.Shadow;
import java.util.IdentityHashMap;
import java.util.Map;
@Mixin(targets = {"net/minecraftforge/registries/NamespacedWrapper"}, priority = 500)
public abstract class NamespacedWrapperMixin<T> {
@Shadow private volatile Map<TagKey<T>, HolderSet.Named<T>> tags;
@Shadow(aliases = {"createTag"}) protected abstract HolderSet.Named<T> m_211067_(TagKey<T> key);
/**
* @author embeddedt (issue found by Uncandango)
* @reason vanilla does not use the correct double-checked locking paradigm, which leads to race conditions
*/
@Overwrite
public HolderSet.Named<T> getOrCreateTag(TagKey<T> key) {
HolderSet.Named<T> named = this.tags.get(key);
if (named == null) {
// synchronize and check again - this is the bugfix
synchronized (this) {
named = this.tags.get(key);
if (named == null) {
named = this.m_211067_(key);
Map<TagKey<T>, HolderSet.Named<T>> map = new IdentityHashMap<>(this.tags);
map.put(key, named);
this.tags = map;
}
}
}
return named;
}
}