mirror of
https://github.com/PaperMC/Paper.git
synced 2024-12-01 12:41:50 +01:00
c5a10665b8
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.
91 lines
4.2 KiB
Diff
91 lines
4.2 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
|
|
From: Aikar <aikar@aikar.co>
|
|
Date: Fri, 29 May 2020 20:29:02 -0400
|
|
Subject: [PATCH] Synchronize PalettedContainer instead of
|
|
ThreadingDetector/Semaphore
|
|
|
|
Mojang has flaws in their logic about chunks being concurrently
|
|
wrote to. So we constantly see crashes around multiple threads writing.
|
|
|
|
Additionally, java has optimized synchronization so well that its
|
|
in many times faster than trying to manage read write locks for low
|
|
contention situations.
|
|
|
|
And this is extremely a low contention situation.
|
|
|
|
diff --git a/src/main/java/net/minecraft/world/level/chunk/PalettedContainer.java b/src/main/java/net/minecraft/world/level/chunk/PalettedContainer.java
|
|
index 2e5afbd2a69c4eeabd9a48bff6a37a7004565716..2fa0097a9374a89177e4f1068d1bfed30b8ff122 100644
|
|
--- a/src/main/java/net/minecraft/world/level/chunk/PalettedContainer.java
|
|
+++ b/src/main/java/net/minecraft/world/level/chunk/PalettedContainer.java
|
|
@@ -30,14 +30,14 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
|
|
public final IdMap<T> registry;
|
|
private volatile PalettedContainer.Data<T> data;
|
|
private final PalettedContainer.Strategy strategy;
|
|
- private final ThreadingDetector threadingDetector = new ThreadingDetector("PalettedContainer");
|
|
+ // private final ThreadingDetector threadingDetector = new ThreadingDetector("PalettedContainer"); // Paper - unused
|
|
|
|
public void acquire() {
|
|
- this.threadingDetector.checkAndLock();
|
|
+ // this.threadingDetector.checkAndLock(); // Paper - disable this - use proper synchronization
|
|
}
|
|
|
|
public void release() {
|
|
- this.threadingDetector.checkAndUnlock();
|
|
+ // this.threadingDetector.checkAndUnlock(); // Paper - disable this
|
|
}
|
|
|
|
public static <T> Codec<PalettedContainer<T>> codecRW(IdMap<T> idList, Codec<T> entryCodec, PalettedContainer.Strategy paletteProvider, T defaultValue) {
|
|
@@ -104,7 +104,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
|
|
}
|
|
|
|
@Override
|
|
- public int onResize(int newBits, T object) {
|
|
+ public synchronized int onResize(int newBits, T object) { // Paper - synchronize
|
|
PalettedContainer.Data<T> data = this.data;
|
|
PalettedContainer.Data<T> data2 = this.createOrReuseData(data, newBits);
|
|
data2.copyFrom(data.palette, data.storage);
|
|
@@ -129,7 +129,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
|
|
return this.getAndSet(this.strategy.getIndex(x, y, z), value);
|
|
}
|
|
|
|
- private T getAndSet(int index, T value) {
|
|
+ private synchronized T getAndSet(int index, T value) { // Paper - synchronize
|
|
int i = this.data.palette.idFor(value);
|
|
int j = this.data.storage.getAndSet(index, i);
|
|
return this.data.palette.valueFor(j);
|
|
@@ -145,7 +145,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
|
|
}
|
|
}
|
|
|
|
- private void set(int index, T value) {
|
|
+ private synchronized void set(int index, T value) { // Paper - synchronize
|
|
int i = this.data.palette.idFor(value);
|
|
this.data.storage.set(index, i);
|
|
}
|
|
@@ -168,7 +168,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
|
|
intSet.forEach(id -> action.accept(palette.valueFor(id)));
|
|
}
|
|
|
|
- public void read(FriendlyByteBuf buf) {
|
|
+ public synchronized void read(FriendlyByteBuf buf) { // Paper - synchronize
|
|
this.acquire();
|
|
|
|
try {
|
|
@@ -183,7 +183,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
|
|
}
|
|
|
|
@Override
|
|
- public void write(FriendlyByteBuf buf) {
|
|
+ public synchronized void write(FriendlyByteBuf buf) { // Paper - synchronize
|
|
this.acquire();
|
|
|
|
try {
|
|
@@ -231,7 +231,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
|
|
}
|
|
|
|
@Override
|
|
- public PalettedContainerRO.PackedData<T> pack(IdMap<T> idList, PalettedContainer.Strategy paletteProvider) {
|
|
+ public synchronized PalettedContainerRO.PackedData<T> pack(IdMap<T> idList, PalettedContainer.Strategy paletteProvider) { // Paper - synchronize
|
|
this.acquire();
|
|
|
|
PalettedContainerRO.PackedData var12;
|