Paper/patches/server/0627-Prevent-excessive-velocity-through-repeated-crits.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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2.0 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Nassim Jahnke <nassim@njahnke.dev>
Date: Thu, 25 Nov 2021 10:25:09 +0100
Subject: [PATCH] Prevent excessive velocity through repeated crits
diff --git a/src/main/java/net/minecraft/world/entity/LivingEntity.java b/src/main/java/net/minecraft/world/entity/LivingEntity.java
index 4132b5dfbc6a7693f0bb923a8b14ded571560030..ee7bb1a01bf027eb7b28e3795950a17e5f686815 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -2773,17 +2773,29 @@ public abstract class LivingEntity extends Entity implements Attackable {
return this.hasEffect(MobEffects.JUMP) ? 0.1F * ((float) this.getEffect(MobEffects.JUMP).getAmplifier() + 1.0F) : 0.0F;
}
+ protected long lastJumpTime = 0L; // Paper - Prevent excessive velocity through repeated crits
@VisibleForTesting
public void jumpFromGround() {
float f = this.getJumpPower();
if (f > 1.0E-5F) {
Vec3 vec3d = this.getDeltaMovement();
+ // Paper start - Prevent excessive velocity through repeated crits
+ long time = System.nanoTime();
+ boolean canCrit = true;
+ if (this instanceof net.minecraft.world.entity.player.Player) {
+ canCrit = false;
+ if (time - this.lastJumpTime > (long)(0.250e9)) {
+ this.lastJumpTime = time;
+ canCrit = true;
+ }
+ }
+ // Paper end - Prevent excessive velocity through repeated crits
this.setDeltaMovement(vec3d.x, (double) f, vec3d.z);
if (this.isSprinting()) {
float f1 = this.getYRot() * 0.017453292F;
-
+ if (canCrit) // Paper - Prevent excessive velocity through repeated crits
this.addDeltaMovement(new Vec3((double) (-Mth.sin(f1)) * 0.2D, 0.0D, (double) Mth.cos(f1) * 0.2D));
}