From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Martijn Muijsers Date: Tue, 22 Aug 2023 21:38:37 +0200 Subject: [PATCH] Optimize VarLong#write License: GPL-3.0 (https://www.gnu.org/licenses/gpl-3.0.html) Gale - https://galemc.org This patch is based on the following commit: "Reapply "Optimize varint writing"" By: Andrew Steinborn As part of: Velocity (https://github.com/PaperMC/Velocity) Licensed under: GPL-3.0 (https://www.gnu.org/licenses/gpl-3.0.html) * Velocity description * Inspired by the approach described at the bottom of https://richardstartin.github.io/posts/dont-use-protobuf-for-telemetry Given that we do a lot of varint writing as well, this should provide a small performance boost for larger/complex packets whilst not regressing hard on smaller packets. This includes a test to ensure that the behavior is as expected and fixes the initialization loop so that the correct results will be given. Much thanks to @octylFractal for acting as my duck while trying to figure this out. diff --git a/src/main/java/net/minecraft/network/VarLong.java b/src/main/java/net/minecraft/network/VarLong.java index 4c1fbf3e2e6cfaf5f5db199b232d007ec6a9d226..10546fb8b47b54989f5f98ddf37f202699abfb6d 100644 --- a/src/main/java/net/minecraft/network/VarLong.java +++ b/src/main/java/net/minecraft/network/VarLong.java @@ -54,6 +54,127 @@ public class VarLong { } public static ByteBuf write(ByteBuf buf, long l) { + // Gale start - Velocity - optimized VarLong#write + if ((l & 0xFFFFFFFFFFFFFF80L) == 0) { + buf.writeByte((int) l); + } else if (l < 0) { + // The case of writing arbitrary longs is common + // Here, the number is negative, which has probability 1/2 for arbitrary numbers + int least7bits = (int) (l & 0xFFFFFFFL); + int w = (least7bits & 0x7F) << 24 + | (least7bits & 0x3F80) << 9 + | (least7bits & 0x1FC000) >> 6 + | ((least7bits >>> 21) & 0x7F) + | 0x80808080; + long nonLeast7Bits = l >>> 28; + int secondLeast7bits = (int) (nonLeast7Bits & 0xFFFFFFFL); + int w2 = (secondLeast7bits & 0x7F) << 24 + | ((secondLeast7bits & 0x3F80) << 9) + | (secondLeast7bits & 0x1FC000) >> 6 + | (secondLeast7bits >>> 21) + | 0x80808080; + int thirdLeast7Bits = (int) (nonLeast7Bits >>> 28); + int w3 = (thirdLeast7Bits & 0x7F) << 8 + | (thirdLeast7Bits >>> 7) + | 0x00008000; + buf.writeInt(w); + buf.writeInt(w2); + buf.writeShort(w3); + } else if ((l & 0xFFFFFFFFFFFFC000L) == 0) { + int least7bits = (int) l; + int w = (least7bits & 0x7F) << 8 + | (least7bits >>> 7) + | 0x00008000; + buf.writeShort(w); + } else if ((l & 0xFFFFFFFFFFE00000L) == 0) { + int least7bits = (int) l; + int w = (least7bits & 0x7F) << 16 + | (least7bits & 0x3F80) << 1 + | (least7bits >>> 14) + | 0x00808000; + buf.writeMedium(w); + } else if ((l & 0xFFFFFFFFF0000000L) == 0) { + int least7bits = (int) l; + int w = (least7bits & 0x7F) << 24 + | ((least7bits & 0x3F80) << 9) + | (least7bits & 0x1FC000) >> 6 + | (least7bits >>> 21) + | 0x80808000; + buf.writeInt(w); + } else if ((l & 0xFFFFFFF800000000L) == 0) { + int least7bits = (int) (l & 0xFFFFFFFL); + int w = (least7bits & 0x7F) << 24 + | (least7bits & 0x3F80) << 9 + | (least7bits & 0x1FC000) >> 6 + | ((least7bits >>> 21) & 0x7F) + | 0x80808080; + buf.writeInt(w); + buf.writeByte((int) (l >>> 28)); + } else if ((l & 0xFFFFFC0000000000L) == 0) { + int least7bits = (int) (l & 0xFFFFFFFL); + int w = (least7bits & 0x7F) << 24 + | (least7bits & 0x3F80) << 9 + | (least7bits & 0x1FC000) >> 6 + | ((least7bits >>> 21) & 0x7F) + | 0x80808080; + int secondLeast7bits = (int) (l >>> 28); + int w2 = (secondLeast7bits & 0x7F) << 8 + | (secondLeast7bits >>> 7) + | 0x00008000; + buf.writeInt(w); + buf.writeShort(w2); + } else if ((l & 0xFFFE000000000000L) == 0) { + int least7bits = (int) (l & 0xFFFFFFFL); + int w = (least7bits & 0x7F) << 24 + | (least7bits & 0x3F80) << 9 + | (least7bits & 0x1FC000) >> 6 + | ((least7bits >>> 21) & 0x7F) + | 0x80808080; + int secondLeast7bits = (int) (l >>> 28); + int w2 = (secondLeast7bits & 0x7F) << 16 + | (secondLeast7bits & 0x3F80) << 1 + | (secondLeast7bits >>> 14) + | 0x00808000; + buf.writeInt(w); + buf.writeMedium(w2); + } else if ((l & 0xFF00000000000000L) == 0) { + int least7bits = (int) (l & 0xFFFFFFFL); + int w = (least7bits & 0x7F) << 24 + | (least7bits & 0x3F80) << 9 + | (least7bits & 0x1FC000) >> 6 + | ((least7bits >>> 21) & 0x7F) + | 0x80808080; + int secondLeast7bits = (int) (l >>> 28); + int w2 = (secondLeast7bits & 0x7F) << 24 + | ((secondLeast7bits & 0x3F80) << 9) + | (secondLeast7bits & 0x1FC000) >> 6 + | (secondLeast7bits >>> 21) + | 0x80808000; + buf.writeInt(w); + buf.writeInt(w2); + } else { + int least7bits = (int) (l & 0xFFFFFFFL); + int w = (least7bits & 0x7F) << 24 + | (least7bits & 0x3F80) << 9 + | (least7bits & 0x1FC000) >> 6 + | ((least7bits >>> 21) & 0x7F) + | 0x80808080; + long nonLeast7Bits = l >>> 28; + int secondLeast7bits = (int) (nonLeast7Bits & 0xFFFFFFFL); + int w2 = (secondLeast7bits & 0x7F) << 24 + | ((secondLeast7bits & 0x3F80) << 9) + | (secondLeast7bits & 0x1FC000) >> 6 + | (secondLeast7bits >>> 21) + | 0x80808080; + buf.writeInt(w); + buf.writeInt(w2); + buf.writeByte((int) (nonLeast7Bits >>> 28)); + } + return buf; + } + + static ByteBuf writeOriginal(ByteBuf buf, long l) { // public -> package-private + // Gale end - Velocity - optimized VarLong#write while((l & -128L) != 0L) { buf.writeByte((int)(l & 127L) | 128); l >>>= 7; diff --git a/src/test/java/net/minecraft/network/VarIntLongTest.java b/src/test/java/net/minecraft/network/VarIntLongTest.java index a1892a904042fcfad9137df592dabd46d4d1c30b..892877b1a1ebfe42bb7a7af7555606329c39e9b3 100644 --- a/src/test/java/net/minecraft/network/VarIntLongTest.java +++ b/src/test/java/net/minecraft/network/VarIntLongTest.java @@ -2,6 +2,7 @@ package net.minecraft.network; +import io.netty.buffer.Unpooled; import it.unimi.dsi.fastutil.ints.IntOpenHashSet; import it.unimi.dsi.fastutil.ints.IntSet; import it.unimi.dsi.fastutil.longs.LongOpenHashSet; @@ -156,4 +157,46 @@ public class VarIntLongTest { } // Gale end - Velocity - pre-compute VarInt and VarLong sizes + // Gale - Velocity - optimized VarInt#write and VarLong#write + @Test + public void testWriteVarIntComparedToOld() { + integerCases.forEach(value -> { + // given + int capacity = 5; + FriendlyByteBuf buf1 = new FriendlyByteBuf(Unpooled.buffer(capacity)); + FriendlyByteBuf buf2 = new FriendlyByteBuf(Unpooled.buffer(capacity)); + VarInt.writeOld(buf1, value); + + // when + buf2.writeVarInt(value); + + // then + Assertions.assertEquals(Float.parseFloat("Writer index of optimized buffer (" + buf2.writerIndex() + ") is not equal to writer index of original buffer (" + buf1.writerIndex() + ") for test case value " + value + " (binary: " + padStringWithLeadingZeros(Integer.toBinaryString(value), 32) + ")"), buf1.writerIndex(), buf2.writerIndex()); + for (int i = 0; i < capacity; i++) { + Assertions.assertEquals(Float.parseFloat("Buffer byte (at index " + i + ") in optimized buffer (" + buf2.getByte(i) + " (binary: " + padStringWithLeadingZeros(Integer.toBinaryString(Byte.toUnsignedInt(buf2.getByte(i))), 8) + ")) is not equal to the same byte in original buffer (" + buf1.getByte(i) + " (binary: " + padStringWithLeadingZeros(Integer.toBinaryString(Byte.toUnsignedInt(buf1.getByte(i))), 8) + ")) for test case value " + value + " (binary: " + padStringWithLeadingZeros(Integer.toBinaryString(value), 32) + ")"), buf1.getByte(i), buf2.getByte(i)); + } + }); + } + + @Test + public void testWriteVarLongComparedToOriginal() { + longCases.forEach(value -> { + // given + int capacity = 10; + FriendlyByteBuf buf1 = new FriendlyByteBuf(Unpooled.buffer(capacity)); + FriendlyByteBuf buf2 = new FriendlyByteBuf(Unpooled.buffer(capacity)); + VarLong.writeOriginal(buf1, value); + + // when + buf2.writeVarLong(value); + + // then + Assertions.assertEquals(Float.parseFloat("Writer index of optimized buffer (" + buf2.writerIndex() + ") is not equal to writer index of original buffer (" + buf1.writerIndex() + ") for test case value " + value + " (binary: " + padStringWithLeadingZeros(Long.toBinaryString(value), 64) + ")"), buf1.writerIndex(), buf2.writerIndex()); + for (int i = 0; i < capacity; i++) { + Assertions.assertEquals(Float.parseFloat("Buffer byte (at index " + i + ") in optimized buffer (" + buf2.getByte(i) + " (binary: " + padStringWithLeadingZeros(Integer.toBinaryString(Byte.toUnsignedInt(buf2.getByte(i))), 8) + ")) is not equal to the same byte in original buffer (" + buf1.getByte(i) + " (binary: " + padStringWithLeadingZeros(Integer.toBinaryString(Byte.toUnsignedInt(buf1.getByte(i))), 8) + ")) for test case value " + value + " (binary: " + padStringWithLeadingZeros(Long.toBinaryString(value), 64) + ")"), buf1.getByte(i), buf2.getByte(i)); + } + }); + } + // Gale end - Velocity - optimized VarInt#write and VarLong#write + }