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Add a MinecraftVarintLengthCompositeEncoder for backend connections
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This is an optimization that has been in BungeeCord for some time, but it's an idea that makes a lot of sense: avoid a memory copy when we don't need to do one. The OS will hopefully be smart enough to use `writev()` or similar for this.
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astei committed Sep 2, 2024
1 parent 956fca1 commit acde360
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Showing 2 changed files with 48 additions and 2 deletions.
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Expand Up @@ -30,7 +30,7 @@
import com.velocitypowered.proxy.protocol.netty.MinecraftDecoder;
import com.velocitypowered.proxy.protocol.netty.MinecraftEncoder;
import com.velocitypowered.proxy.protocol.netty.MinecraftVarintFrameDecoder;
import com.velocitypowered.proxy.protocol.netty.MinecraftVarintLengthEncoder;
import com.velocitypowered.proxy.protocol.netty.MinecraftVarintLengthCompositeEncoder;
import io.netty.channel.Channel;
import io.netty.channel.ChannelInitializer;
import io.netty.handler.timeout.ReadTimeoutHandler;
Expand All @@ -55,7 +55,7 @@ protected void initChannel(Channel ch) throws Exception {
.addLast(READ_TIMEOUT,
new ReadTimeoutHandler(server.getConfiguration().getReadTimeout(),
TimeUnit.MILLISECONDS))
.addLast(FRAME_ENCODER, MinecraftVarintLengthEncoder.INSTANCE)
.addLast(FRAME_ENCODER, MinecraftVarintLengthCompositeEncoder.INSTANCE)
.addLast(MINECRAFT_DECODER,
new MinecraftDecoder(ProtocolUtils.Direction.CLIENTBOUND))
.addLast(FLOW_HANDLER, new AutoReadHolderHandler())
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/*
* Copyright (C) 2018-2023 Velocity 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 <https://www.gnu.org/licenses/>.
*/

package com.velocitypowered.proxy.protocol.netty;

import com.velocitypowered.proxy.protocol.ProtocolUtils;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageEncoder;
import java.util.List;

/**
* Handler for appending a length for Minecraft packets using composite buffers.
*/
@ChannelHandler.Sharable
public class MinecraftVarintLengthCompositeEncoder extends MessageToMessageEncoder<ByteBuf> {

public static final MinecraftVarintLengthCompositeEncoder INSTANCE = new MinecraftVarintLengthCompositeEncoder();

private MinecraftVarintLengthCompositeEncoder() {
}

@Override
protected void encode(ChannelHandlerContext ctx, ByteBuf buf,
List<Object> list) throws Exception {
ByteBuf varIntBuffer = ctx.alloc().ioBuffer(ProtocolUtils.varIntBytes(buf.readableBytes()));
ProtocolUtils.writeVarInt(varIntBuffer, buf.readableBytes());
list.add(varIntBuffer);
list.add(buf.retain());
}
}

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