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Remove wall-time / unused skip tick protection (#11412)

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Spigot still maintains some partial implementation of "tick skipping", a
practice in which the MinecraftServer.currentTick field is updated not
by an increment of one per actual tick, but instead set to
System.currentTimeMillis() / 50. This behaviour means that the tracked
tick may "skip" a tick value in case a previous tick took more than the
expected 50ms.

To compensate for this in important paths, spigot/craftbukkit
implements "wall-time". Instead of incrementing/decrementing ticks on
block entities/entities by one for each call to their tick() method,
they instead increment/decrement important values, like
an ItemEntity's age or pickupDelay, by the difference of
`currentTick - lastTick`, where `lastTick` is the value of
`currentTick` during the last tick() call.

These "fixes" however do not play nicely with minecraft's simulation
distance as entities/block entities implementing the above behaviour
would "catch up" their values when moving from a non-ticking chunk to a
ticking one as their `lastTick` value remains stuck on the last tick in
a ticking chunk and hence lead to a large "catch up" once ticked again.

Paper completely removes the "tick skipping" behaviour (See patch
"Further-improve-server-tick-loop"), making the above precautions
completely unnecessary, which also rids paper of the previous described
incompatibility with non-ticking chunks.
This commit is contained in:
Bjarne Koll 2024-09-19 16:36:07 +02:00 • committed by GitHub
parent 5c82955733
commit c5a10665b8
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GPG key ID: B5690EEEBB952194
794 changed files with 402 additions and 282 deletions
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65
patches/server/0327-Add-Raw-Byte-ItemStack-Serialization.patch Normal file
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@ -0,0 +1,65 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Mariell Hoversholm <proximyst@proximyst.com>
Date: Thu, 30 Apr 2020 16:56:54 +0200
Subject: [PATCH] Add Raw Byte ItemStack Serialization
Serializes using NBT which is safer for server data migrations than bukkits format.
diff --git a/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java b/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
index d08b01fef9928f2239c8663cf90219dc7acad58c..af706146a26ede6b9f5a39c8deb490ff25334ae6 100644
--- a/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
+++ b/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
@@ -458,6 +458,53 @@ public final class CraftMagicNumbers implements UnsafeValues {
public com.destroystokyo.paper.util.VersionFetcher getVersionFetcher() {
return new com.destroystokyo.paper.PaperVersionFetcher();
}
+
+ @Override
+ public byte[] serializeItem(ItemStack item) {
+ Preconditions.checkNotNull(item, "null cannot be serialized");
+ Preconditions.checkArgument(item.getType() != Material.AIR, "air cannot be serialized");
+
+ return serializeNbtToBytes((net.minecraft.nbt.CompoundTag) (item instanceof CraftItemStack ? ((CraftItemStack) item).handle : CraftItemStack.asNMSCopy(item)).save(MinecraftServer.getServer().registryAccess()));
+ }
+
+ @Override
+ public ItemStack deserializeItem(byte[] data) {
+ Preconditions.checkNotNull(data, "null cannot be deserialized");
+ Preconditions.checkArgument(data.length > 0, "cannot deserialize nothing");
+
+ net.minecraft.nbt.CompoundTag compound = deserializeNbtFromBytes(data);
+ final int dataVersion = compound.getInt("DataVersion");
+ compound = (net.minecraft.nbt.CompoundTag) MinecraftServer.getServer().fixerUpper.update(References.ITEM_STACK, new Dynamic<>(NbtOps.INSTANCE, compound), dataVersion, this.getDataVersion()).getValue();
+ return CraftItemStack.asCraftMirror(net.minecraft.world.item.ItemStack.parse(MinecraftServer.getServer().registryAccess(), compound).orElseThrow());
+ }
+
+ private byte[] serializeNbtToBytes(CompoundTag compound) {
+ compound.putInt("DataVersion", getDataVersion());
+ java.io.ByteArrayOutputStream outputStream = new java.io.ByteArrayOutputStream();
+ try {
+ net.minecraft.nbt.NbtIo.writeCompressed(
+ compound,
+ outputStream
+ );
+ } catch (IOException ex) {
+ throw new RuntimeException(ex);
+ }
+ return outputStream.toByteArray();
+ }
+
+ private net.minecraft.nbt.CompoundTag deserializeNbtFromBytes(byte[] data) {
+ net.minecraft.nbt.CompoundTag compound;
+ try {
+ compound = net.minecraft.nbt.NbtIo.readCompressed(
+ new java.io.ByteArrayInputStream(data), net.minecraft.nbt.NbtAccounter.unlimitedHeap()
+ );
+ } catch (IOException ex) {
+ throw new RuntimeException(ex);
+ }
+ int dataVersion = compound.getInt("DataVersion");
+ Preconditions.checkArgument(dataVersion <= getDataVersion(), "Newer version! Server downgrades are not supported!");
+ return compound;
+ }
// Paper end
@Override