src/main/java/com/tiedup/remake/v2/bondage/datadriven/DataDrivenItemRegistry.java

@@ -48,6 +48,9 @@ public final class DataDrivenItemRegistry {
      */
     private static volatile RegistrySnapshot SNAPSHOT = RegistrySnapshot.EMPTY;
 
+    /** Guards read-then-write sequences in {@link #reload} and {@link #mergeAll}. */
+    private static final Object RELOAD_LOCK = new Object();
+
     private DataDrivenItemRegistry() {}
 
     /**
@@ -59,10 +62,12 @@ public final class DataDrivenItemRegistry {
     public static void reload(
         Map<ResourceLocation, DataDrivenItemDefinition> newDefs
     ) {
+        synchronized (RELOAD_LOCK) {
             Map<ResourceLocation, DataDrivenItemDefinition> defs =
                 Collections.unmodifiableMap(new HashMap<>(newDefs));
             SNAPSHOT = new RegistrySnapshot(defs, buildComponentHolders(defs));
         }
+    }
 
     /**
      * Atomically merge new definitions into the existing registry.
@@ -78,6 +83,7 @@ public final class DataDrivenItemRegistry {
     public static void mergeAll(
         Map<ResourceLocation, DataDrivenItemDefinition> newDefs
     ) {
+        synchronized (RELOAD_LOCK) {
             Map<ResourceLocation, DataDrivenItemDefinition> merged = new HashMap<>(
                 SNAPSHOT.definitions
             );
@@ -86,6 +92,7 @@ public final class DataDrivenItemRegistry {
                 Collections.unmodifiableMap(merged);
             SNAPSHOT = new RegistrySnapshot(defs, buildComponentHolders(defs));
         }
+    }
 
     /**
      * Get a definition by its unique ID.
@@ -95,7 +102,8 @@ public final class DataDrivenItemRegistry {
      */
     @Nullable
     public static DataDrivenItemDefinition get(ResourceLocation id) {
-        return SNAPSHOT.definitions.get(id);
+        RegistrySnapshot snap = SNAPSHOT;
+        return snap.definitions.get(id);
     }
 
     /**
@@ -113,7 +121,8 @@ public final class DataDrivenItemRegistry {
             tag.getString(NBT_ITEM_ID)
         );
         if (id == null) return null;
-        return SNAPSHOT.definitions.get(id);
+        RegistrySnapshot snap = SNAPSHOT;
+        return snap.definitions.get(id);
     }
 
     /**
@@ -122,7 +131,8 @@ public final class DataDrivenItemRegistry {
      * @return unmodifiable collection of all definitions
      */
     public static Collection<DataDrivenItemDefinition> getAll() {
-        return SNAPSHOT.definitions.values();
+        RegistrySnapshot snap = SNAPSHOT;
+        return snap.definitions.values();
     }
 
     /**
@@ -168,7 +178,8 @@ public final class DataDrivenItemRegistry {
      */
     @Nullable
     public static ComponentHolder getComponents(ResourceLocation id) {
-        return SNAPSHOT.holders.get(id);
+        RegistrySnapshot snap = SNAPSHOT;
+        return snap.holders.get(id);
     }
 
     /**