Add isNewChunk to ChunkEvent.Load (#9369)

patches/minecraft/net/minecraft/client/multiplayer/ClientChunkCache.java.patch

@@ -12,7 +12,7 @@
           }
  
           this.f_104411_.m_171649_(chunkpos);
-+         net.minecraftforge.common.MinecraftForge.EVENT_BUS.post(new net.minecraftforge.event.level.ChunkEvent.Load(levelchunk));
++         net.minecraftforge.common.MinecraftForge.EVENT_BUS.post(new net.minecraftforge.event.level.ChunkEvent.Load(levelchunk, false));
           return levelchunk;
        }
     }

patches/minecraft/net/minecraft/server/level/ChunkMap.java.patch

@@ -24,7 +24,7 @@
 +               p_140384_.currentlyLoading = levelchunk; // Forge - bypass the future chain when getChunk is called, this prevents deadlocks.
                 levelchunk.m_156369_();
                 levelchunk.m_187958_(this.f_140133_);
-+               net.minecraftforge.common.MinecraftForge.EVENT_BUS.post(new net.minecraftforge.event.level.ChunkEvent.Load(levelchunk));
++               net.minecraftforge.common.MinecraftForge.EVENT_BUS.post(new net.minecraftforge.event.level.ChunkEvent.Load(levelchunk, !(protochunk instanceof ImposterProtoChunk)));
 +               } finally {
 +                   p_140384_.currentlyLoading = null; // Forge - Stop bypassing the future chain.
 +               }

src/main/java/net/minecraftforge/event/level/ChunkEvent.java

@@ -12,6 +12,7 @@ import net.minecraft.world.level.chunk.LevelChunk;
 import net.minecraftforge.common.MinecraftForge;
 import net.minecraftforge.eventbus.api.Cancelable;
 import net.minecraftforge.eventbus.api.Event;
+import org.jetbrains.annotations.ApiStatus;
 
 /**
  * ChunkEvent is fired when an event involving a chunk occurs.<br>
@@ -58,9 +59,32 @@ public class ChunkEvent extends LevelEvent
      **/
     public static class Load extends ChunkEvent
     {
+        private final boolean newChunk;
+
+        @ApiStatus.Internal
+        @Deprecated(forRemoval = true, since = "1.19.3")
         public Load(ChunkAccess chunk)
+        {
+            this(chunk, false);
+        }
+
+        @ApiStatus.Internal
+        public Load(ChunkAccess chunk, boolean newChunk)
         {
             super(chunk);
+            this.newChunk = newChunk;
+        }
+
+        /**
+         * Check whether the Chunk is newly generated, and being loaded for the first time.
+         *
+         * <p>Will only ever return {@code true} on the {@linkplain net.minecraftforge.fml.LogicalSide#SERVER logical server}.</p>
+         *
+         * @return whether the Chunk is newly generated
+         */
+        public boolean isNewChunk()
+        {
+            return newChunk;
         }
     }
 

src/test/java/net/minecraftforge/debug/world/ChunkEventLoadNewChunkTest.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) Forge Development LLC and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.minecraftforge.debug.world;
+
+import com.mojang.logging.LogUtils;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraftforge.event.level.ChunkEvent;
+import net.minecraftforge.eventbus.api.SubscribeEvent;
+import net.minecraftforge.fml.common.Mod;
+import org.slf4j.Logger;
+
+/**
+ * Simple test for {@link ChunkEvent.Load#isNewChunk()}. Will log a message to console each time
+ * the event is fired for a newly generated chunk.
+ *
+ * <p>A simple way to check that it's behaving as expected is as follows:</p>
+ * <ul>
+ * <li>Generate a new world (and log in if using dedicated server). You should see many log messages about
+ * the spawn chunks being generated.</li>
+ * <li>Don't move around in game, to make sure we only generate the spawn chunks, and any chunks loaded
+ * by the player chunk loader for the players initial login position. (to make this test as
+ * reproducible as possible without lots of complexity)</li>
+ * <li>Once a couple seconds pass without any new chunk log messages, close out of the world/stop the server.</li>
+ * <li>Load the world/start the server (and log in if using dedicated server) again. For the same reasons as before,
+ * don't move around.</li>
+ * <li>You shouldn't see any log messages for new chunks this time.
+ * (until you start moving around to generate more chunks)</li>
+ * </ul>
+ */
+@Mod(ChunkEventLoadNewChunkTest.MODID)
+@Mod.EventBusSubscriber
+public class ChunkEventLoadNewChunkTest
+{
+    static final String MODID = "chunk_event_load_new_chunk_test";
+    private static final boolean ENABLED = true;
+    private static final Logger LOGGER = LogUtils.getLogger();
+
+    @SubscribeEvent
+    public static void onChunkLoad(final ChunkEvent.Load event)
+    {
+        if (!ENABLED)
+        {
+            return;
+        }
+
+        if (!event.isNewChunk())
+        {
+            return;
+        }
+
+        LOGGER.info("Loaded freshly generated chunk at {}{}", ((ServerLevel) event.getLevel()).dimension().location(), event.getChunk().getPos());
+    }
+}

src/test/resources/META-INF/mods.toml

@@ -280,6 +280,8 @@ modId="creative_mode_tab_test"
 modId="render_level_stages_test"
 [[mods]]
 modId="trade_with_villager_event_test"
+[[mods]]
+modId="chunk_event_load_new_chunk_test"
 
 
 # ADD ABOVE THIS LINE