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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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31
patches/server/0362-Maps-shouldn-t-load-chunks.patch Normal file
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@ -0,0 +1,31 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Phoenix616 <mail@moep.tv>
Date: Sun, 7 Jun 2020 21:43:42 +0100
Subject: [PATCH] Maps shouldn't load chunks
Previously maps would load all chunks in a certain radius depending on
their scale when trying to update their content. This would result in
main thread chunk loads when they weren't really necessary, especially
on low view distances or "slow" async chunk loads after teleports or
other prioritisation.
This changes it to only try to render already loaded chunks based on
the assumption that the chunks around the player will get loaded
eventually anyways and that maps will get checked for update every
five ticks that movement occur in anyways.
diff --git a/src/main/java/net/minecraft/world/item/MapItem.java b/src/main/java/net/minecraft/world/item/MapItem.java
index 4e6d42051de14a1a62184fbb586ea38fb31261b3..36de7c63370c529579d31ba1d77ec12b754ef313 100644
--- a/src/main/java/net/minecraft/world/item/MapItem.java
+++ b/src/main/java/net/minecraft/world/item/MapItem.java
@@ -98,8 +98,8 @@ public class MapItem extends ComplexItem {
int r = (j / i + o - 64) * i;
int s = (k / i + p - 64) * i;
Multiset<MapColor> multiset = LinkedHashMultiset.create();
- LevelChunk levelChunk = world.getChunk(SectionPos.blockToSectionCoord(r), SectionPos.blockToSectionCoord(s));
- if (!levelChunk.isEmpty()) {
+ LevelChunk levelChunk = world.getChunkIfLoaded(SectionPos.blockToSectionCoord(r), SectionPos.blockToSectionCoord(s)); // Paper - Maps shouldn't load chunks
+ if (levelChunk != null && !levelChunk.isEmpty()) { // Paper - Maps shouldn't load chunks
int t = 0;
double e = 0.0;
if (world.dimensionType().hasCeiling()) {