Pre-size most allocated byte buffers

Also avoids the default allocation size of 256 bytes for bufs that are much smaller than that

bukkit/src/main/java/com/viaversion/viaversion/bukkit/handlers/BukkitDecodeHandler.java

@@ -22,6 +22,7 @@ import com.viaversion.viaversion.bukkit.util.NMSUtil;
 import com.viaversion.viaversion.exception.CancelCodecException;
 import com.viaversion.viaversion.exception.CancelDecoderException;
 import com.viaversion.viaversion.exception.InformativeException;
+import com.viaversion.viaversion.util.ByteBufUtil;
 import com.viaversion.viaversion.util.PipelineUtil;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandler;
@@ -39,7 +40,7 @@ public final class BukkitDecodeHandler extends MessageToMessageDecoder<ByteBuf>
     }
 
     @Override
-    protected void decode(final ChannelHandlerContext ctx, final ByteBuf bytebuf, final List<Object> out) throws Exception {
+    protected void decode(final ChannelHandlerContext ctx, final ByteBuf bytebuf, final List<Object> out) {
         if (!connection.checkServerboundPacket()) {
             throw CancelDecoderException.generate(null);
         }
@@ -48,7 +49,7 @@ public final class BukkitDecodeHandler extends MessageToMessageDecoder<ByteBuf>
             return;
         }
 
-        final ByteBuf transformedBuf = ctx.alloc().buffer().writeBytes(bytebuf);
+        final ByteBuf transformedBuf = ByteBufUtil.copy(ctx.alloc(), bytebuf);
         try {
             connection.transformIncoming(transformedBuf, CancelDecoderException::generate);
             out.add(transformedBuf.retain());

bukkit/src/main/java/com/viaversion/viaversion/bukkit/handlers/BukkitEncodeHandler.java

@@ -22,6 +22,7 @@ import com.viaversion.viaversion.bukkit.util.NMSUtil;
 import com.viaversion.viaversion.exception.CancelCodecException;
 import com.viaversion.viaversion.exception.CancelEncoderException;
 import com.viaversion.viaversion.exception.InformativeException;
+import com.viaversion.viaversion.util.ByteBufUtil;
 import com.viaversion.viaversion.util.PipelineUtil;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandler;
@@ -52,7 +53,7 @@ public final class BukkitEncodeHandler extends MessageToMessageEncoder<ByteBuf>
             return;
         }
 
-        final ByteBuf transformedBuf = ctx.alloc().buffer().writeBytes(bytebuf);
+        final ByteBuf transformedBuf = ByteBufUtil.copy(ctx.alloc(), bytebuf);
         try {
             final boolean needsCompression = !handledCompression && handleCompressionOrder(ctx, transformedBuf);
             connection.transformClientbound(transformedBuf, CancelEncoderException::generate);

common/src/main/java/com/viaversion/viaversion/connection/UserConnectionImpl.java

@@ -55,6 +55,7 @@ import java.util.function.Function;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class UserConnectionImpl implements UserConnection {
+    private static final int PASSTHROUGH_DATA_BYTES = Long.BYTES * 2 + 2;
     private static final AtomicLong IDS = new AtomicLong();
     private final long id = IDS.incrementAndGet();
     private final Map<Class<?>, StorableObject> storedObjects = new ConcurrentHashMap<>();
@@ -244,7 +245,8 @@ public class UserConnectionImpl implements UserConnection {
     }
 
     private void sendRawPacketToServerServerSide(final ByteBuf packet, final boolean currentThread) {
-        final ByteBuf buf = packet.alloc().buffer();
+        final int initialCapacity = active ? packet.readableBytes() + PASSTHROUGH_DATA_BYTES : packet.readableBytes();
+        final ByteBuf buf = packet.alloc().buffer(initialCapacity);
         try {
             // We'll use passing through because there are some encoder wrappers
             ChannelHandlerContext context = PipelineUtil
@@ -341,7 +343,7 @@ public class UserConnectionImpl implements UserConnection {
             return;
         }
 
-        PacketWrapper wrapper = new PacketWrapperImpl(id, buf, this);
+        PacketWrapperImpl wrapper = new PacketWrapperImpl(id, buf, this);
         State state = protocolInfo.getState(direction);
         try {
             protocolInfo.getPipeline().transform(direction, state, wrapper);
@@ -349,7 +351,7 @@ public class UserConnectionImpl implements UserConnection {
             throw cancelSupplier.apply(ex);
         }
 
-        ByteBuf transformed = buf.alloc().buffer();
+        ByteBuf transformed = wrapper.allocateOutputBuffer();
         try {
             wrapper.writeToBuffer(transformed);
             buf.clear().writeBytes(transformed);

common/src/main/java/com/viaversion/viaversion/protocol/packet/PacketWrapperImpl.java

@@ -320,7 +320,7 @@ public class PacketWrapperImpl implements PacketWrapper {
         final ProtocolInfo protocolInfo = user().getProtocolInfo();
         final List<Protocol> protocols = protocolInfo.getPipeline().pipes(protocolClass, skipCurrentPipeline, direction);
         apply(direction, protocolInfo.getState(direction), protocols);
-        final ByteBuf output = inputBuffer == null ? user().getChannel().alloc().buffer() : inputBuffer.alloc().buffer();
+        final ByteBuf output = allocateOutputBuffer();
         try {
             writeToBuffer(output);
             return output.retain();
@@ -354,7 +354,7 @@ public class PacketWrapperImpl implements PacketWrapper {
             return cancelledFuture();
         }
 
-        ByteBuf output = inputBuffer == null ? user().getChannel().alloc().buffer() : inputBuffer.alloc().buffer();
+        ByteBuf output = allocateOutputBuffer();
         try {
             writeToBuffer(output);
             return user().sendRawPacketFuture(output.retain());
@@ -373,7 +373,7 @@ public class PacketWrapperImpl implements PacketWrapper {
             return;
         }
 
-        ByteBuf output = inputBuffer == null ? user().getChannel().alloc().buffer() : inputBuffer.alloc().buffer();
+        ByteBuf output = allocateOutputBuffer();
         try {
             writeToBuffer(output);
             if (currentThread) {
@@ -386,6 +386,14 @@ public class PacketWrapperImpl implements PacketWrapper {
         }
     }
 
+    public ByteBuf allocateOutputBuffer() {
+        if (inputBuffer == null) {
+            return user().getChannel().alloc().buffer();
+        }
+        // May have already been partially or fully read
+        return inputBuffer.alloc().buffer(Math.max(inputBuffer.readableBytes(), 256));
+    }
+
     private ChannelFuture cancelledFuture() {
         return user().getChannel().newFailedFuture(new RuntimeException("Tried to send cancelled packet"));
     }
@@ -454,7 +462,7 @@ public class PacketWrapperImpl implements PacketWrapper {
             return;
         }
 
-        ByteBuf output = inputBuffer == null ? user().getChannel().alloc().buffer() : inputBuffer.alloc().buffer();
+        ByteBuf output = allocateOutputBuffer();
         try {
             writeToBuffer(output);
             if (currentThread) {

common/src/main/java/com/viaversion/viaversion/util/ByteBufUtil.java

@@ -0,0 +1,29 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2024 ViaVersion and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package com.viaversion.viaversion.util;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufAllocator;
+
+public final class ByteBufUtil {
+
+    public static ByteBuf copy(final ByteBufAllocator allocator, final ByteBuf from) {
+        final int bytes = from.readableBytes();
+        return allocator.buffer(bytes).writeBytes(from, bytes);
+    }
+}

common/src/main/java/com/viaversion/viaversion/util/SerializerVersion.java

@@ -48,7 +48,8 @@ public enum SerializerVersion {
     V1_18(TextComponentSerializer.V1_18, SNbtSerializer.V1_14),
     V1_19_4(TextComponentSerializer.V1_19_4, SNbtSerializer.V1_14),
     V1_20_3(TextComponentCodec.V1_20_3, SNbtSerializer.V1_14),
-    V1_20_5(TextComponentCodec.V1_20_5, SNbtSerializer.V1_14);
+    V1_20_5(TextComponentCodec.V1_20_5, SNbtSerializer.V1_14),
+    V1_21_4(TextComponentCodec.V1_21_4, SNbtSerializer.V1_14);
 
     final TextComponentSerializer jsonSerializer;
     final SNbtSerializer<? extends Tag> snbtSerializer;

velocity/src/main/java/com/viaversion/viaversion/velocity/handlers/VelocityDecodeHandler.java

@@ -20,6 +20,7 @@ package com.viaversion.viaversion.velocity.handlers;
 import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.exception.CancelCodecException;
 import com.viaversion.viaversion.exception.CancelDecoderException;
+import com.viaversion.viaversion.util.ByteBufUtil;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandler;
 import io.netty.channel.ChannelHandlerContext;
@@ -43,7 +44,7 @@ public class VelocityDecodeHandler extends MessageToMessageDecoder<ByteBuf> {
             return;
         }
 
-        ByteBuf transformedBuf = ctx.alloc().buffer().writeBytes(bytebuf);
+        ByteBuf transformedBuf = ByteBufUtil.copy(ctx.alloc(), bytebuf);
         try {
             info.transformIncoming(transformedBuf, CancelDecoderException::generate);
             out.add(transformedBuf.retain());

velocity/src/main/java/com/viaversion/viaversion/velocity/handlers/VelocityEncodeHandler.java

@@ -20,6 +20,7 @@ package com.viaversion.viaversion.velocity.handlers;
 import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.exception.CancelCodecException;
 import com.viaversion.viaversion.exception.CancelEncoderException;
+import com.viaversion.viaversion.util.ByteBufUtil;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandler;
 import io.netty.channel.ChannelHandlerContext;
@@ -42,7 +43,7 @@ public class VelocityEncodeHandler extends MessageToMessageEncoder<ByteBuf> {
             return;
         }
 
-        ByteBuf transformedBuf = ctx.alloc().buffer().writeBytes(bytebuf);
+        ByteBuf transformedBuf = ByteBufUtil.copy(ctx.alloc(), bytebuf);
         try {
             info.transformOutgoing(transformedBuf, CancelEncoderException::generate);
             out.add(transformedBuf.retain());