PaperMC/patches/server/0572-Optimize-entity-tracker-passenger-checks.patch
Bjarne Koll c5a10665b8
Remove wall-time / unused skip tick protection (#11412)
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.
2024-09-19 16:36:07 +02:00

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Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Andrew Steinborn <git@steinborn.me>
Date: Sun, 8 Aug 2021 00:52:54 -0400
Subject: [PATCH] Optimize entity tracker passenger checks
diff --git a/src/main/java/net/minecraft/server/level/ServerEntity.java b/src/main/java/net/minecraft/server/level/ServerEntity.java
index 9f04dc7817909d81f387b03bfc57d2d9a1d63478..7e8a43ea1b32f444fb66e270a5f6b48bf7bcd2a0 100644
--- a/src/main/java/net/minecraft/server/level/ServerEntity.java
+++ b/src/main/java/net/minecraft/server/level/ServerEntity.java
@@ -71,7 +71,7 @@ public class ServerEntity {
private Vec3 lastSentMovement;
private int tickCount;
private int teleportDelay;
- private List<Entity> lastPassengers = Collections.emptyList();
+ private List<Entity> lastPassengers = com.google.common.collect.ImmutableList.of(); // Paper - optimize passenger checks
private boolean wasRiding;
private boolean wasOnGround;
@Nullable