Improving chunk generation performance

src/main/java/net/minestom/server/extras/mojangAuth/CipherBase.java

@@ -2,16 +2,18 @@ package net.minestom.server.extras.mojangAuth;
 
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;
+import org.jetbrains.annotations.NotNull;
 
 import javax.crypto.Cipher;
 import javax.crypto.ShortBufferException;
 
 public class CipherBase {
+
     private final Cipher cipher;
     private byte[] inTempArray = new byte[0];
     private byte[] outTempArray = new byte[0];
 
-   protected CipherBase(Cipher cipher) {
+    protected CipherBase(@NotNull Cipher cipher) {
         this.cipher = cipher;
     }
 

src/main/java/net/minestom/server/instance/InstanceContainer.java

@@ -503,7 +503,7 @@ public class InstanceContainer extends Instance {
     @Override
     public ChunkBatch createChunkBatch(@NotNull Chunk chunk) {
         Check.notNull(chunk, "The chunk of a ChunkBatch cannot be null");
-        return new ChunkBatch(this, chunk);
+        return new ChunkBatch(this, chunk, false);
     }
 
     @Override
@@ -540,7 +540,7 @@ public class InstanceContainer extends Instance {
 
         if (chunkGenerator != null && chunk.shouldGenerate()) {
             // Execute the chunk generator to populate the chunk
-            final ChunkBatch chunkBatch = createChunkBatch(chunk);
+            final ChunkBatch chunkBatch = new ChunkBatch(this, chunk, true);
 
             chunkBatch.flushChunkGenerator(chunkGenerator, callback);
         } else {

src/main/java/net/minestom/server/instance/batch/ChunkBatch.java

@@ -31,6 +31,8 @@ public class ChunkBatch implements InstanceBatch {
     private final InstanceContainer instance;
     private final Chunk chunk;
 
+    private final boolean generationBatch;
+
     // Need to be synchronized manually
     // Format: blockIndex/blockStateId/customBlockId (32/16/16 bits)
     private final LongList blocks = new LongArrayList();
@@ -39,9 +41,11 @@ public class ChunkBatch implements InstanceBatch {
     // block index - data
     private final Int2ObjectMap<Data> blockDataMap = new Int2ObjectOpenHashMap<>();
 
-    public ChunkBatch(@NotNull InstanceContainer instance, @NotNull Chunk chunk) {
+    public ChunkBatch(@NotNull InstanceContainer instance, @NotNull Chunk chunk,
+                      boolean generationBatch) {
         this.instance = instance;
         this.chunk = chunk;
+        this.generationBatch = generationBatch;
     }
 
     @Override
@@ -62,6 +66,10 @@ public class ChunkBatch implements InstanceBatch {
     }
 
     private void addBlockData(byte x, int y, byte z, short blockStateId, short customBlockId, @Nullable Data data) {
+
+        if (isGenerationBatch()) {
+            chunk.UNSAFE_setBlock(x, y, z, blockStateId, customBlockId, data, CustomBlockUtils.hasUpdate(customBlockId));
+        } else {
             final int index = ChunkUtils.getBlockIndex(x, y, z);
 
             if (data != null) {
@@ -78,6 +86,20 @@ public class ChunkBatch implements InstanceBatch {
                 this.blocks.add(value);
             }
         }
+    }
+
+    /**
+     * Gets if this chunk batch is part of a chunk generation.
+     * <p>
+     * Being a generation batch mean that blocks set are not being stored
+     * but are immediately placed on the chunks. Using less memory
+     * and CPU cycles.
+     *
+     * @return true if this batch is part of a chunk generation
+     */
+    public boolean isGenerationBatch() {
+        return generationBatch;
+    }
 
     /**
      * Called to fill the chunk batch.
@@ -92,24 +114,15 @@ public class ChunkBatch implements InstanceBatch {
 
             chunkGenerator.generateChunkData(this, chunk.getChunkX(), chunk.getChunkZ());
 
-            // Check if there is anything to process
-            if (blocks.isEmpty() && !hasPopulator) {
-                OptionalCallback.execute(callback, chunk);
-                return;
-            }
-
-            singleThreadFlush(hasPopulator ? null : callback, true);
-
-            clearData(); // So the populators won't place those blocks again
-
             if (hasPopulator) {
                 for (ChunkPopulator chunkPopulator : populators) {
                     chunkPopulator.populateChunk(this, chunk);
                 }
-                singleThreadFlush(callback, true);
-
-                clearData(); // Clear populators blocks
             }
+
+            instance.scheduleNextTick(inst -> {
+                OptionalCallback.execute(callback, chunk);
+            });
         });
     }
 

src/test/java/demo/PlayerInit.java

@@ -30,7 +30,6 @@ import net.minestom.server.utils.time.TimeUnit;
 import net.minestom.server.world.DimensionType;
 
 import java.util.UUID;
-import java.util.concurrent.ThreadLocalRandom;
 
 public class PlayerInit {
 
@@ -44,7 +43,7 @@ public class PlayerInit {
         NoiseTestGenerator noiseTestGenerator = new NoiseTestGenerator();
         instanceContainer = MinecraftServer.getInstanceManager().createInstanceContainer(DimensionType.OVERWORLD);
         instanceContainer.enableAutoChunkLoad(true);
-        instanceContainer.setChunkGenerator(chunkGeneratorDemo);
+        instanceContainer.setChunkGenerator(noiseTestGenerator);
 
         // Load some chunks beforehand
         final int loopStart = -3;
@@ -163,8 +162,8 @@ public class PlayerInit {
             player.addEventCallback(PlayerLoginEvent.class, event -> {
 
                 event.setSpawningInstance(instanceContainer);
-                int x = ThreadLocalRandom.current().nextInt()%10000;
-                player.setRespawnPoint(new Position(x, 64f, 0));
+                //int x = ThreadLocalRandom.current().nextInt()%10000;
+                player.setRespawnPoint(new Position(0, 64f, 0));
 
                 /*player.getInventory().addInventoryCondition((p, slot, clickType, inventoryConditionResult) -> {
                     if (slot == -999)