PaperMC/patches/server/0995-Remove-wall-time-unused-skip-tick-protection.patch

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Bjarne Koll <git@lynxplay.dev>
Date: Mon, 16 Sep 2024 23:07:29 +0200
Subject: [PATCH] Remove wall-time / unused skip tick protection
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.
diff --git a/src/main/java/net/minecraft/world/entity/item/ItemEntity.java b/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
index 4ce041726661dbbd19f36a516f2fd7f5e3307ef0..0f086af57a5ff08c264dcbf89a8c3931ec73a609 100644
--- a/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
+++ b/src/main/java/net/minecraft/world/entity/item/ItemEntity.java
@@ -60,7 +60,7 @@ public class ItemEntity extends Entity implements TraceableEntity {
@Nullable
public UUID target;
public final float bobOffs;
- private int lastTick = MinecraftServer.currentTick - 1; // CraftBukkit
+ // private int lastTick = MinecraftServer.currentTick - 1; // CraftBukkit // Paper - remove anti tick skipping measures / wall time
public boolean canMobPickup = true; // Paper - Item#canEntityPickup
private int despawnRate = -1; // Paper - Alternative item-despawn-rate
public net.kyori.adventure.util.TriState frictionState = net.kyori.adventure.util.TriState.NOT_SET; // Paper - Friction API
@@ -153,12 +153,11 @@ public class ItemEntity extends Entity implements TraceableEntity {
this.discard(EntityRemoveEvent.Cause.DESPAWN); // CraftBukkit - add Bukkit remove cause
} else {
super.tick();
- // CraftBukkit start - Use wall time for pickup and despawn timers
- int elapsedTicks = MinecraftServer.currentTick - this.lastTick;
- if (this.pickupDelay != 32767) this.pickupDelay -= elapsedTicks;
- if (this.age != -32768) this.age += elapsedTicks;
- this.lastTick = MinecraftServer.currentTick;
- // CraftBukkit end
+ // Paper start - remove anti tick skipping measures / wall time - revert to vanilla
+ if (this.pickupDelay > 0 && this.pickupDelay != 32767) {
+ --this.pickupDelay;
+ }
+ // Paper end - remove anti tick skipping measures / wall time - revert to vanilla
this.xo = this.getX();
this.yo = this.getY();
2024-10-25 12:28:34 +02:00
@@ -212,7 +211,7 @@ public class ItemEntity extends Entity implements TraceableEntity {
this.mergeWithNeighbours();
}
- /* CraftBukkit start - moved up
+ // Paper - remove anti tick skipping measures / wall time - revert to vanilla /* CraftBukkit start - moved up
if (this.age != -32768) {
++this.age;
}
2024-10-25 12:28:34 +02:00
@@ -243,12 +242,14 @@ public class ItemEntity extends Entity implements TraceableEntity {
// Spigot start - copied from above
@Override
public void inactiveTick() {
- // CraftBukkit start - Use wall time for pickup and despawn timers
- int elapsedTicks = MinecraftServer.currentTick - this.lastTick;
- if (this.pickupDelay != 32767) this.pickupDelay -= elapsedTicks;
- if (this.age != -32768) this.age += elapsedTicks;
- this.lastTick = MinecraftServer.currentTick;
- // CraftBukkit end
+ // Paper start - remove anti tick skipping measures / wall time - copied from above
+ if (this.pickupDelay > 0 && this.pickupDelay != 32767) {
+ --this.pickupDelay;
+ }
+ if (this.age != -32768) {
+ ++this.age;
+ }
+ // Paper end - remove anti tick skipping measures / wall time - copied from above
if (!this.level().isClientSide && this.age >= this.despawnRate) { // Spigot // Paper - Alternative item-despawn-rate
// CraftBukkit start - fire ItemDespawnEvent
diff --git a/src/main/java/net/minecraft/world/entity/monster/Zombie.java b/src/main/java/net/minecraft/world/entity/monster/Zombie.java
2024-10-25 13:34:01 +02:00
index 94b3ba2688676e92d9d093b63d92cab39d5d2f02..a12461907278cfbfa3b1c0aa74b9f07a31768b8a 100644
--- a/src/main/java/net/minecraft/world/entity/monster/Zombie.java
+++ b/src/main/java/net/minecraft/world/entity/monster/Zombie.java
2024-10-25 12:28:34 +02:00
@@ -98,7 +98,7 @@ public class Zombie extends Monster {
private boolean canBreakDoors;
private int inWaterTime;
public int conversionTime;
- private int lastTick = MinecraftServer.currentTick; // CraftBukkit - add field
+ // private int lastTick = MinecraftServer.currentTick; // CraftBukkit - add field // Paper - remove anti tick skipping measures / wall time
private boolean shouldBurnInDay = true; // Paper - Add more Zombie API
public Zombie(EntityType<? extends Zombie> type, Level world) {
2024-10-25 12:28:34 +02:00
@@ -217,10 +217,7 @@ public class Zombie extends Monster {
public void tick() {
if (!this.level().isClientSide && this.isAlive() && !this.isNoAi()) {
if (this.isUnderWaterConverting()) {
- // CraftBukkit start - Use wall time instead of ticks for conversion
- int elapsedTicks = MinecraftServer.currentTick - this.lastTick;
- this.conversionTime -= elapsedTicks;
- // CraftBukkit end
+ --this.conversionTime; // Paper - remove anti tick skipping measures / wall time
if (this.conversionTime < 0) {
this.doUnderWaterConversion();
}
2024-10-25 12:28:34 +02:00
@@ -237,7 +234,7 @@ public class Zombie extends Monster {
}
super.tick();
- this.lastTick = MinecraftServer.currentTick; // CraftBukkit
+ // this.lastTick = MinecraftServer.currentTick; // CraftBukkit // Paper - remove anti tick skipping measures / wall time
}
@Override
2024-10-25 12:28:34 +02:00
@@ -278,7 +275,7 @@ public class Zombie extends Monster {
}
// Paper end - Add more Zombie API
public void startUnderWaterConversion(int ticksUntilWaterConversion) {
- this.lastTick = MinecraftServer.currentTick; // CraftBukkit
+ // this.lastTick = MinecraftServer.currentTick; // CraftBukkit // Paper - remove anti tick skipping measures / wall time
this.conversionTime = ticksUntilWaterConversion;
this.getEntityData().set(Zombie.DATA_DROWNED_CONVERSION_ID, true);
}
diff --git a/src/main/java/net/minecraft/world/level/block/entity/BrewingStandBlockEntity.java b/src/main/java/net/minecraft/world/level/block/entity/BrewingStandBlockEntity.java
2024-10-25 12:28:34 +02:00
index 2bafacd7bc56186d9105d2031180f8c4a6940018..4ea29e8f2b39d7b44e0461d6a2cdd3fc257abd44 100644
--- a/src/main/java/net/minecraft/world/level/block/entity/BrewingStandBlockEntity.java
+++ b/src/main/java/net/minecraft/world/level/block/entity/BrewingStandBlockEntity.java
2024-10-25 12:28:34 +02:00
@@ -55,7 +55,7 @@ public class BrewingStandBlockEntity extends BaseContainerBlockEntity implements
public int fuel;
protected final ContainerData dataAccess;
// CraftBukkit start - add fields and methods
- private int lastTick = MinecraftServer.currentTick;
+ // private int lastTick = MinecraftServer.currentTick; // Paper - remove anti tick skipping measures / wall time
public List<HumanEntity> transaction = new java.util.ArrayList<HumanEntity>();
private int maxStack = MAX_STACK;
2024-10-25 12:28:34 +02:00
@@ -170,12 +170,10 @@ public class BrewingStandBlockEntity extends BaseContainerBlockEntity implements
boolean flag1 = blockEntity.brewTime > 0;
ItemStack itemstack1 = (ItemStack) blockEntity.items.get(3);
- // CraftBukkit start - Use wall time instead of ticks for brewing
- int elapsedTicks = MinecraftServer.currentTick - blockEntity.lastTick;
- blockEntity.lastTick = MinecraftServer.currentTick;
+ // Paper - remove anti tick skipping measures / wall time
if (flag1) {
- blockEntity.brewTime -= elapsedTicks;
+ --blockEntity.brewTime; // Paper - remove anti tick skipping measures / wall time - revert to vanilla
boolean flag2 = blockEntity.brewTime <= 0; // == -> <=
// CraftBukkit end