Improve TagsUpdatedEvent by adding update case information. (#8636)

src/main/java/net/minecraftforge/common/ForgeInternalHandler.java

@@ -99,9 +99,12 @@ public class ForgeInternalHandler
     }
 
     @SubscribeEvent
-    public synchronized void tagsUpdated(TagsUpdatedEvent event)
+    public void tagsUpdated(TagsUpdatedEvent event)
     {
-        ForgeHooks.updateBurns();
+        if (event.shouldUpdateStaticData())
+        {
+            ForgeHooks.updateBurns();
+        }
     }
 
     @SubscribeEvent

src/main/java/net/minecraftforge/event/TagsUpdatedEvent.java

@@ -6,22 +6,73 @@
 package net.minecraftforge.event;
 
 import net.minecraft.core.RegistryAccess;
+import net.minecraft.network.protocol.game.ClientGamePacketListener;
 import net.minecraftforge.eventbus.api.Event;
+import net.minecraftforge.server.ServerLifecycleHooks;
 
+/**
+ * Fired when tags are updated on either server or client. This event can be used to refresh data that depends on tags.
+ */
 public class TagsUpdatedEvent extends Event
 {
     private final RegistryAccess registries;
+    private final UpdateCause updateCause;
+    private final boolean integratedServer;
 
-     public TagsUpdatedEvent(RegistryAccess registries)
-     {
-         this.registries = registries;
-     }
+    @Deprecated(forRemoval = true, since = "1.18.2")
+    public TagsUpdatedEvent(RegistryAccess registries)
+    {
+        this.registries = registries;
+        this.updateCause = ClientGamePacketListener.class.isAssignableFrom(StackWalker.getInstance(StackWalker.Option.RETAIN_CLASS_REFERENCE).getCallerClass()) ? UpdateCause.CLIENT_PACKET_RECEIVED : UpdateCause.SERVER_DATA_LOAD;
+        var currentServer = ServerLifecycleHooks.getCurrentServer();
+        this.integratedServer = currentServer != null && !currentServer.isDedicatedServer();
+    }
 
-     /**
-      * @return The dynamic registries that have had their tags rebound.
-      */
-     public RegistryAccess getTagManager()
-     {
-         return registries;
-     }
+    public TagsUpdatedEvent(RegistryAccess registries, boolean fromClientPacket, boolean isIntegratedServerConnection)
+    {
+        this.registries = registries;
+        this.updateCause = fromClientPacket ? UpdateCause.CLIENT_PACKET_RECEIVED : UpdateCause.SERVER_DATA_LOAD;
+        this.integratedServer = isIntegratedServerConnection;
+    }
+
+    /**
+     * @return The dynamic registries that have had their tags rebound.
+     */
+    public RegistryAccess getTagManager()
+    {
+        return registries;
+    }
+
+    /**
+     * @return the cause for this tag update
+     */
+    public UpdateCause getUpdateCause()
+    {
+        return updateCause;
+    }
+
+    /**
+     * Whether static data (which in single player is shared between server and client thread) should be updated as a
+     * result of this event. Effectively this means that in single player only the server-side updates this data.
+     */
+    public boolean shouldUpdateStaticData()
+    {
+        return updateCause == UpdateCause.SERVER_DATA_LOAD || !integratedServer;
+    }
+
+    /**
+     * Represents the cause for a tag update.
+     */
+    public enum UpdateCause
+    {
+        /**
+         * The tag update is caused by the server loading datapack data. Note that in single player this still happens
+         * on the client thread.
+         */
+        SERVER_DATA_LOAD,
+        /**
+         * The tag update is caused by the client receiving the tag data from the server.
+         */
+        CLIENT_PACKET_RECEIVED
+    }
 }