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Mirror von https://github.com/PaperMC/Paper.git synchronisiert 2024-11-15 04:20:04 +01:00
Paper/patches/server/0887-Fix-race-condition-on-UpgradeData.BlockFixers-class-.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

28 Zeilen
1.5 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Tue, 8 Aug 2023 17:29:33 -0700
Subject: [PATCH] Fix race condition on UpgradeData.BlockFixers class init
The CHUNKY_FIXERS field is modified during the constructors
of the BlockFixers, but the code that uses CHUNKY_FIXERS does
not properly ensure that BlockFixers has been initialised before
using it, leading to a possible race condition where instances of
BlockFixers are accessed before they have initialised correctly.
We can force the class to initialise fully before accessing the
field by calling any method on the class, and for convenience
we use values().
diff --git a/src/main/java/net/minecraft/world/level/chunk/UpgradeData.java b/src/main/java/net/minecraft/world/level/chunk/UpgradeData.java
index 22b6d0851a51da180cd8fbbe6554c5370f5ac5bd..cd9b65f278a750a0177a3252271015d43172b2e9 100644
--- a/src/main/java/net/minecraft/world/level/chunk/UpgradeData.java
+++ b/src/main/java/net/minecraft/world/level/chunk/UpgradeData.java
@@ -140,6 +140,7 @@ public class UpgradeData {
Fluid fluid = tick.type() == Fluids.EMPTY ? level.getFluidState(tick.pos()).getType() : tick.type();
level.scheduleTick(tick.pos(), fluid, tick.delay(), tick.priority());
});
+ UpgradeData.BlockFixers.values(); // Paper - force the class init so that we don't access CHUNKY_FIXERS before all BlockFixers are initialised
CHUNKY_FIXERS.forEach(logic -> logic.processChunk(level));
}