New AddReloadListenerEvent that gathers server side data reload handlers. (#6849)

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

@@ -109,6 +109,8 @@ import net.minecraft.world.IWorld;
 import net.minecraft.world.IWorldReader;
 import net.minecraft.world.World;
 import net.minecraftforge.common.data.IOptionalTagEntry;
+import net.minecraftforge.common.loot.IGlobalLootModifier;
+import net.minecraftforge.common.loot.LootModifierManager;
 import net.minecraftforge.common.util.BlockSnapshot;
 import net.minecraftforge.event.AnvilUpdateEvent;
 import net.minecraftforge.event.DifficultyChangeEvent;
@@ -1165,12 +1167,10 @@ public class ForgeHooks
      * @return The modified list
      */
     public static List<ItemStack> modifyLoot(List<ItemStack> list, LootContext context) {
-    	/*
-        LootModifierManager man = context.getWorld().getServer().getLootModifierManager();
+        LootModifierManager man = ForgeInternalHandler.getLootModifierManager();
         for(IGlobalLootModifier mod : man.getAllLootMods()) {
             list = mod.apply(list, context);
         }
-        */
         return list;
     }
 

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

@@ -25,7 +25,9 @@ import net.minecraft.entity.player.ServerPlayerEntity;
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
 import net.minecraft.world.server.ServerWorld;
+import net.minecraftforge.common.loot.LootModifierManager;
 import net.minecraftforge.common.util.FakePlayerFactory;
+import net.minecraftforge.event.AddReloadListenerEvent;
 import net.minecraftforge.event.entity.EntityJoinWorldEvent;
 import net.minecraftforge.event.entity.player.PlayerEvent;
 import net.minecraftforge.event.world.ChunkEvent;
@@ -109,5 +111,21 @@ public class ForgeInternalHandler
     {
         ForgeHooks.updateBurns();
     }
+
+    private static LootModifierManager INSTANCE;
+
+    @SubscribeEvent
+    public void onResourceReload(AddReloadListenerEvent event)
+    {
+        INSTANCE = new LootModifierManager();
+        event.addListener(INSTANCE);
+    }
+
+    static LootModifierManager getLootModifierManager()
+    {
+        if(INSTANCE == null)
+            throw new IllegalStateException("Can not retrieve LootModifierManager until resources have loaded once.");
+        return INSTANCE;
+    }
 }
 

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

@@ -0,0 +1,34 @@
+package net.minecraftforge.event;
+
+import com.google.common.collect.ImmutableList;
+import net.minecraft.resources.DataPackRegistries;
+import net.minecraft.resources.IFutureReloadListener;
+import net.minecraftforge.common.MinecraftForge;
+import net.minecraftforge.eventbus.api.Event;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * The main ResourceManager is recreated on each reload, through {@link DataPackRegistries}'s creation.
+ *
+ * The event is fired on each reload and lets modders add their own ReloadListeners, for server-side resources.
+ * The event is fired on the {@link MinecraftForge#EVENT_BUS}
+ */
+public class AddReloadListenerEvent extends Event
+{
+   private final List<IFutureReloadListener> listeners = new ArrayList<>();
+
+   /**
+    * @param listener the listener to add to the ResourceManager on reload
+    */
+   public void addListener(IFutureReloadListener listener)
+   {
+      listeners.add(listener);
+   }
+
+   public List<IFutureReloadListener> getListeners()
+   {
+      return ImmutableList.copyOf(listeners);
+   }
+}

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

@@ -51,6 +51,7 @@ import net.minecraft.item.ItemStack;
 import net.minecraft.item.ItemUseContext;
 import net.minecraft.loot.LootTable;
 import net.minecraft.loot.LootTableManager;
+import net.minecraft.resources.IFutureReloadListener;
 import net.minecraft.world.spawner.AbstractSpawner;
 import net.minecraft.util.ActionResult;
 import net.minecraft.util.ActionResultType;
@@ -722,4 +723,11 @@ public class ForgeEventFactory
         MinecraftForge.EVENT_BUS.post(event);
         return event.getNewTime();
     }
+
+    public static List<IFutureReloadListener> onResourceReload()
+    {
+        AddReloadListenerEvent event = new AddReloadListenerEvent();
+        MinecraftForge.EVENT_BUS.post(event);
+        return event.getListeners();
+    }
 }