Optimize NibbleArray to use pooled buffers

Massively reduces memory allocation of 2048 byte buffers by using
an object pool for these.

Spigot-Server-Patches/MC-Utils.patch

@@ -2090,18 +2090,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +
 +public final class PooledObjects<E> {
 +
-+    public static final PooledObjects<MutableInt> POOLED_MUTABLE_INTEGERS = new PooledObjects<>(new PooledObjectHandler<MutableInt>() {
++    public static final PooledObjects<MutableInt> POOLED_MUTABLE_INTEGERS = new PooledObjects<>(MutableInt::new, 200, -1);
-+        @Override
-+        public MutableInt createNew() {
-+            return new MutableInt();
-+        }
-+
-+        @Override
-+        public void onAcquire(final MutableInt value) {}
-+
-+        @Override
-+        public void onRelease(final MutableInt value) {}
-+    }, 200, -1);
 +
 +    private final PooledObjectHandler<E> handler;
 +    private final int maxPoolSize;
@@ -2171,16 +2160,16 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +    }
 +
 +    /** This object is restricted from interacting with any pool */
-+    static interface PooledObjectHandler<E> {
++    public static interface PooledObjectHandler<E> {
 +
 +        /**
 +         * Must return a non-null object
 +         */
 +        E createNew();
 +
-+        void onAcquire(final E value);
++        default void onAcquire(final E value) {}
 +
-+        void onRelease(final E value);
++        default void onRelease(final E value) {}
 +    }
 +
 +    protected static class IsolatedPool<E> {

Spigot-Server-Patches/Optimize-Network-Manager-and-add-advanced-packet-sup.patch

@@ -4,7 +4,8 @@ Date: Wed, 6 May 2020 04:53:35 -0400
 Subject: [PATCH] Optimize Network Manager and add advanced packet support
 
 Adds ability for 1 packet to bundle other packets to follow it
-adds ability for a packet to delay sending more packets until a state is ready.
+Adds ability for a packet to delay sending more packets until a state is ready.
+Adds ability to clean up a packet when it is finished (not sent, or finished encoding), such as freeing buffers
 
 Removes synchronization from sending packets
 Removes processing packet queue off of main thread
@@ -93,7 +94,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 -            this.packetQueue.add(new NetworkManager.QueuedPacket(packet, genericfuturelistener));
 +        // Paper start - handle oversized packets better
 +        boolean connected = this.isConnected();
-+        if (!connected && !preparing) return; // Do nothing
++        if (!connected && !preparing) {
++            packet.onPacketDone();
++            return; // Do nothing
++        }
 +        if (connected && (InnerUtil.canSendImmediate(this, packet) || (
 +            MCUtil.isMainThread() && packet.isReady() && this.packetQueue.isEmpty() &&
 +            (packet.getExtraPackets() == null || packet.getExtraPackets().isEmpty())
@@ -109,13 +113,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +        } else {
 +            java.util.List<NetworkManager.QueuedPacket> packets = new java.util.ArrayList<>(1 + extraPackets.size());
 +            packets.add(new NetworkManager.QueuedPacket(packet, null)); // delay the future listener until the end of the extra packets
- 
++
 +            for (int i = 0, len = extraPackets.size(); i < len;) {
 +                Packet extra = extraPackets.get(i);
 +                boolean end = ++i == len;
 +                packets.add(new NetworkManager.QueuedPacket(extra, end ? genericfuturelistener : null)); // append listener to the end
 +            }
-+
+ 
 +            this.packetQueue.addAll(packets); // atomic
 +        }
 +        this.sendPacketQueue();
@@ -181,13 +185,26 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
      public void a() {
          this.o();
 @@ -0,0 +0,0 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet<?>> {
+         return this.socketAddress;
+     }
+ 
++    public void clearPacketQueue() { QueuedPacket packet; while ((packet = packetQueue.poll()) != null) packet.getPacket().onPacketDone(); } // Paper
      public void close(IChatBaseComponent ichatbasecomponent) {
          // Spigot Start
          this.preparing = false;
-+        this.packetQueue.clear(); // Paper - just incase its closed before we ever get to the main thread to do this
++        clearPacketQueue(); // Paper
          // Spigot End
          if (this.channel.isOpen()) {
              this.channel.close(); // We can't wait as this may be called from an event loop.
+@@ -0,0 +0,0 @@ public class NetworkManager extends SimpleChannelInboundHandler<Packet<?>> {
+                 } else if (this.i() != null) {
+                     this.i().a(new ChatMessage("multiplayer.disconnect.generic", new Object[0]));
+                 }
+-                this.packetQueue.clear(); // Free up packet queue.
++                clearPacketQueue(); // Paper
+                 // Paper start - Add PlayerConnectionCloseEvent
+                 final PacketListener packetListener = this.i();
+                 if (packetListener instanceof PlayerConnection) {
 diff --git a/src/main/java/net/minecraft/server/Packet.java b/src/main/java/net/minecraft/server/Packet.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
 --- a/src/main/java/net/minecraft/server/Packet.java
@@ -196,11 +213,25 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
      void a(T t0);
  
      // Paper start
++    default void onPacketDone() {}
 +    default boolean isReady() { return true; }
 +    default java.util.List<Packet> getExtraPackets() { return null; }
      default boolean packetTooLarge(NetworkManager manager) {
          return false;
      }
+diff --git a/src/main/java/net/minecraft/server/PacketEncoder.java b/src/main/java/net/minecraft/server/PacketEncoder.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/server/PacketEncoder.java
++++ b/src/main/java/net/minecraft/server/PacketEncoder.java
+@@ -0,0 +0,0 @@ public class PacketEncoder extends MessageToByteEncoder<Packet<?>> {
+                     } else {
+                         throw throwable;
+                     }
+-                }
++                } finally { try { packet.onPacketDone(); } catch (Exception e) { e.printStackTrace(); } ; } // Paper
+ 
+                 // Paper start
+                 int packetLength = bytebuf.readableBytes();
 diff --git a/src/main/java/net/minecraft/server/PlayerList.java b/src/main/java/net/minecraft/server/PlayerList.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
 --- a/src/main/java/net/minecraft/server/PlayerList.java

Spigot-Server-Patches/Optimize-NibbleArray-to-use-pooled-buffers.patch

@@ -0,0 +1,215 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Wed, 6 May 2020 23:30:30 -0400
+Subject: [PATCH] Optimize NibbleArray to use pooled buffers
+
+Massively reduces memory allocation of 2048 byte buffers by using
+an object pool for these.
+
+diff --git a/src/main/java/net/minecraft/server/ChunkRegionLoader.java b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/server/ChunkRegionLoader.java
++++ b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
+@@ -0,0 +0,0 @@ public class ChunkRegionLoader {
+                 }
+ 
+                 if (nibblearray != null && !nibblearray.c()) {
+-                    nbttagcompound2.setByteArray("BlockLight", nibblearray.asBytes());
++                    nbttagcompound2.setByteArray("BlockLight", nibblearray.getIfSet()); // Paper
+                 }
+ 
+                 if (nibblearray1 != null && !nibblearray1.c()) {
+-                    nbttagcompound2.setByteArray("SkyLight", nibblearray1.asBytes());
++                    nbttagcompound2.setByteArray("SkyLight", nibblearray1.getIfSet()); // Paper
+                 }
+ 
+                 nbttaglist.add(nbttagcompound2);
+diff --git a/src/main/java/net/minecraft/server/LightEngineStorageSky.java b/src/main/java/net/minecraft/server/LightEngineStorageSky.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/server/LightEngineStorageSky.java
++++ b/src/main/java/net/minecraft/server/LightEngineStorageSky.java
+@@ -0,0 +0,0 @@ public class LightEngineStorageSky extends LightEngineStorage<LightEngineStorage
+                     j = SectionPosition.a(j, EnumDirection.UP);
+                 }
+ 
+-                return new NibbleArray((new NibbleArrayFlat(nibblearray1, 0)).asBytes());
++                return new NibbleArray((new NibbleArrayFlat(nibblearray1, 0)).asBytes(), true); // Paper - mark buffer as safe
+             } else {
+                 return new NibbleArray();
+             }
+diff --git a/src/main/java/net/minecraft/server/NibbleArray.java b/src/main/java/net/minecraft/server/NibbleArray.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/server/NibbleArray.java
++++ b/src/main/java/net/minecraft/server/NibbleArray.java
+@@ -0,0 +0,0 @@
+ package net.minecraft.server;
+ 
++import com.destroystokyo.paper.util.pooled.PooledObjects;
++
+ import javax.annotation.Nullable;
+ 
+ public class NibbleArray {
+ 
+-    @Nullable
+-    protected byte[] a;
++    // Paper start
++    public static byte[] EMPTY_NIBBLE = new byte[2048];
++    public static final PooledObjects<byte[]> BYTE_2048 = new PooledObjects<>(() -> new byte[2048], 16384, 1);
++    public static void releaseBytes(byte[] bytes) {
++        if (bytes != EMPTY_NIBBLE) {
++            System.arraycopy(EMPTY_NIBBLE, 0, bytes, 0, 2048);
++            BYTE_2048.release(bytes);
++        }
++    }
++
++    public byte[] getIfSet() {
++        return this.a != null ? this.a : EMPTY_NIBBLE;
++    }
++    public byte[] getCloneIfSet() {
++        if (a == null) {
++            return EMPTY_NIBBLE;
++        }
++        byte[] ret = BYTE_2048.acquire();
++        System.arraycopy(getIfSet(), 0, ret, 0, 2048);
++        return ret;
++    }
++
++    @Override
++    protected void finalize() throws Throwable {
++        try {
++            if (this.a != null) {
++                releaseBytes(this.a);
++                this.a = null;
++            }
++        } finally {
++            super.finalize();
++        }
++    }
++    // Paper end
++    @Nullable protected byte[] a;
++
+ 
+     public NibbleArray() {}
+ 
+     public NibbleArray(byte[] abyte) {
++        // Paper start
++        this(abyte, false);
++    }
++    public NibbleArray(byte[] abyte, boolean isSafe) {
+         this.a = abyte;
++        if (!isSafe) this.a = getCloneIfSet(); // Paper - clone for safety
++        // Paper end
+         if (abyte.length != 2048) {
+             throw (IllegalArgumentException) SystemUtils.c(new IllegalArgumentException("ChunkNibbleArrays should be 2048 bytes not: " + abyte.length));
+         }
+@@ -0,0 +0,0 @@ public class NibbleArray {
+ 
+     public void a(int i, int j) { // PAIL: private -> public
+         if (this.a == null) {
+-            this.a = new byte[2048];
++            this.a = BYTE_2048.acquire(); // Paper
+         }
+ 
+         int k = this.d(i);
+@@ -0,0 +0,0 @@ public class NibbleArray {
+ 
+     public byte[] asBytes() {
+         if (this.a == null) {
+-            this.a = new byte[2048];
++            this.a = BYTE_2048.acquire(); // Paper
+         }
+ 
+         return this.a;
+@@ -0,0 +0,0 @@ public class NibbleArray {
+ 
+     public NibbleArray copy() { return this.b(); } // Paper - OBFHELPER
+     public NibbleArray b() {
+-        return this.a == null ? new NibbleArray() : new NibbleArray((byte[]) this.a.clone());
++        return this.a == null ? new NibbleArray() : new NibbleArray(this.a); // Paper - clone in ctor
+     }
+ 
+     public String toString() {
+diff --git a/src/main/java/net/minecraft/server/NibbleArrayFlat.java b/src/main/java/net/minecraft/server/NibbleArrayFlat.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/server/NibbleArrayFlat.java
++++ b/src/main/java/net/minecraft/server/NibbleArrayFlat.java
+@@ -0,0 +0,0 @@ public class NibbleArrayFlat extends NibbleArray {
+ 
+     @Override
+     public byte[] asBytes() {
+-        byte[] abyte = new byte[2048];
++        byte[] abyte = BYTE_2048.acquire(); // Paper
+ 
+         for (int i = 0; i < 16; ++i) {
+             System.arraycopy(this.a, 0, abyte, i * 128, 128);
+diff --git a/src/main/java/net/minecraft/server/PacketPlayOutLightUpdate.java b/src/main/java/net/minecraft/server/PacketPlayOutLightUpdate.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/server/PacketPlayOutLightUpdate.java
++++ b/src/main/java/net/minecraft/server/PacketPlayOutLightUpdate.java
+@@ -0,0 +0,0 @@ public class PacketPlayOutLightUpdate implements Packet<PacketListenerPlayOut> {
+     private List<byte[]> h;
+ 
+     public PacketPlayOutLightUpdate() {}
++    // Paper start
++    private final java.util.List<byte[]> usedBytes = new java.util.ArrayList<>();
++
++    @Override
++    public void onPacketDone() {
++        usedBytes.forEach(NibbleArray::releaseBytes);
++        usedBytes.clear();
++    }
++    // Paper end
+ 
+     public PacketPlayOutLightUpdate(ChunkCoordIntPair chunkcoordintpair, LightEngine lightengine) {
+         this.a = chunkcoordintpair.x;
+@@ -0,0 +0,0 @@ public class PacketPlayOutLightUpdate implements Packet<PacketListenerPlayOut> {
+         this.g = Lists.newArrayList();
+         this.h = Lists.newArrayList();
+ 
++        byte[] lastBytes; // Paper
+         for (int i = 0; i < 18; ++i) {
+             NibbleArray nibblearray = lightengine.a(EnumSkyBlock.SKY).a(SectionPosition.a(chunkcoordintpair, -1 + i));
+             NibbleArray nibblearray1 = lightengine.a(EnumSkyBlock.BLOCK).a(SectionPosition.a(chunkcoordintpair, -1 + i));
+@@ -0,0 +0,0 @@ public class PacketPlayOutLightUpdate implements Packet<PacketListenerPlayOut> {
+                     this.e |= 1 << i;
+                 } else {
+                     this.c |= 1 << i;
+-                    this.g.add(nibblearray.asBytes().clone());
++                    this.g.add(lastBytes = nibblearray.getCloneIfSet()); usedBytes.add(lastBytes); // Paper
+                 }
+             }
+ 
+@@ -0,0 +0,0 @@ public class PacketPlayOutLightUpdate implements Packet<PacketListenerPlayOut> {
+                     this.f |= 1 << i;
+                 } else {
+                     this.d |= 1 << i;
+-                    this.h.add(nibblearray1.asBytes().clone());
++                    this.h.add(lastBytes = nibblearray1.getCloneIfSet()); usedBytes.add(lastBytes); // Paper
+                 }
+             }
+         }
+@@ -0,0 +0,0 @@ public class PacketPlayOutLightUpdate implements Packet<PacketListenerPlayOut> {
+         this.g = Lists.newArrayList();
+         this.h = Lists.newArrayList();
+ 
++        byte[] lastBytes; // Paper
+         for (int k = 0; k < 18; ++k) {
+             NibbleArray nibblearray;
+ 
+             if ((this.c & 1 << k) != 0) {
+                 nibblearray = lightengine.a(EnumSkyBlock.SKY).a(SectionPosition.a(chunkcoordintpair, -1 + k));
+                 if (nibblearray != null && !nibblearray.c()) {
+-                    this.g.add(nibblearray.asBytes().clone());
++                    this.g.add(lastBytes = nibblearray.getCloneIfSet()); usedBytes.add(lastBytes); // Paper
+                 } else {
+                     this.c &= ~(1 << k);
+                     if (nibblearray != null) {
+@@ -0,0 +0,0 @@ public class PacketPlayOutLightUpdate implements Packet<PacketListenerPlayOut> {
+             if ((this.d & 1 << k) != 0) {
+                 nibblearray = lightengine.a(EnumSkyBlock.BLOCK).a(SectionPosition.a(chunkcoordintpair, -1 + k));
+                 if (nibblearray != null && !nibblearray.c()) {
+-                    this.h.add(nibblearray.asBytes().clone());
++                    this.h.add(lastBytes = nibblearray.getCloneIfSet()); usedBytes.add(lastBytes); // Paper
+                 } else {
+                     this.d &= ~(1 << k);
+                     if (nibblearray != null) {