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01a13871de
Patch documentation to come Issues with the old system that are fixed now: - World generation does not scale with cpu cores effectively. - Relies on the main thread for scheduling and maintaining chunk state, dropping chunk load/generate rates at lower tps. - Unreliable prioritisation of chunk gen/load calls that block the main thread. - Shutdown logic is utterly unreliable, as it has to wait for all chunks to unload - is it guaranteed that the chunk system is in a state on shutdown that it can reliably do this? Watchdog shutdown also typically failed due to thread checks, which is now resolved. - Saving of data is not unified (i.e can save chunk data without saving entity data, poses problems for desync if shutdown is really abnormal. - Entities are not loaded with chunks. This caused quite a bit of headache for Chunk#getEntities API, but now the new chunk system loads entities with chunks so that they are ready whenever the chunk loads in. Effectively brings the behavior back to 1.16 era, but still storing entities in their own separate regionfiles. The above list is not complete. The patch documentation will complete it. New chunk system hard relies on starlight and dataconverter, and most importantly the new concurrent utilities in ConcurrentUtil. Some of the old async chunk i/o interface (i.e the old file io thread reroutes _some_ calls to the new file io thread) is kept for plugin compat reasons. It will be removed in the next major version of minecraft. The old legacy chunk system patches have been moved to the removed folder in case we need them again.
92 lines
4.4 KiB
Diff
92 lines
4.4 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Aikar <aikar@aikar.co>
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Date: Fri, 29 May 2020 20:29:02 -0400
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Subject: [PATCH] Synchronize PalettedContainer instead of
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ThreadingDetector/Semaphore
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Mojang has flaws in their logic about chunks being concurrently
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wrote to. So we constantly see crashes around multiple threads writing.
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Additionally, java has optimized synchronization so well that its
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in many times faster than trying to manage read write locks for low
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contention situations.
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And this is extremely a low contention situation.
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diff --git a/src/main/java/net/minecraft/world/level/chunk/PalettedContainer.java b/src/main/java/net/minecraft/world/level/chunk/PalettedContainer.java
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index 8f5114b6d64461866140b6d2ced3f838a1228851..9e652cf68b289696b5aee53ac157fc52cca10d2c 100644
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--- a/src/main/java/net/minecraft/world/level/chunk/PalettedContainer.java
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+++ b/src/main/java/net/minecraft/world/level/chunk/PalettedContainer.java
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@@ -32,14 +32,14 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
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private final T @org.jetbrains.annotations.Nullable [] presetValues; // Paper - Anti-Xray - Add preset values
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private volatile PalettedContainer.Data<T> data;
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private final PalettedContainer.Strategy strategy;
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- private final ThreadingDetector threadingDetector = new ThreadingDetector("PalettedContainer");
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+ // private final ThreadingDetector threadingDetector = new ThreadingDetector("PalettedContainer"); // Paper - unused
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public void acquire() {
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- this.threadingDetector.checkAndLock();
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+ // this.threadingDetector.checkAndLock(); // Paper - disable this - use proper synchronization
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}
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public void release() {
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- this.threadingDetector.checkAndUnlock();
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+ // this.threadingDetector.checkAndUnlock(); // Paper - disable this
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}
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// Paper start - Anti-Xray - Add preset values
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@@ -129,7 +129,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
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}
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@Override
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- public int onResize(int newBits, T object) {
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+ public synchronized int onResize(int newBits, T object) { // Paper - synchronize
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PalettedContainer.Data<T> data = this.data;
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// Paper start - Anti-Xray - Add preset values
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@@ -176,7 +176,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
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return this.getAndSet(this.strategy.getIndex(x, y, z), value);
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}
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- private T getAndSet(int index, T value) {
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+ private synchronized T getAndSet(int index, T value) { // Paper - synchronize
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int i = this.data.palette.idFor(value);
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int j = this.data.storage.getAndSet(index, i);
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return this.data.palette.valueFor(j);
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@@ -193,7 +193,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
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}
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- private void set(int index, T value) {
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+ private synchronized void set(int index, T value) { // Paper - synchronize
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int i = this.data.palette.idFor(value);
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this.data.storage.set(index, i);
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}
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@@ -218,7 +218,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
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});
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}
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- public void read(FriendlyByteBuf buf) {
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+ public synchronized void read(FriendlyByteBuf buf) { // Paper - synchronize
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this.acquire();
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try {
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@@ -238,7 +238,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
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@Override
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@Deprecated @io.papermc.paper.annotation.DoNotUse public void write(FriendlyByteBuf buf) { this.write(buf, null, 0); }
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@Override
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- public void write(FriendlyByteBuf buf, @Nullable com.destroystokyo.paper.antixray.ChunkPacketInfo<T> chunkPacketInfo, int bottomBlockY) {
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+ public synchronized void write(FriendlyByteBuf buf, @Nullable com.destroystokyo.paper.antixray.ChunkPacketInfo<T> chunkPacketInfo, int bottomBlockY) { // Paper - synchronize
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this.acquire();
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try {
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@@ -296,7 +296,7 @@ public class PalettedContainer<T> implements PaletteResize<T>, PalettedContainer
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}
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@Override
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- public PalettedContainerRO.PackedData<T> pack(IdMap<T> idList, PalettedContainer.Strategy paletteProvider) {
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+ public synchronized PalettedContainerRO.PackedData<T> pack(IdMap<T> idList, PalettedContainer.Strategy paletteProvider) { // Paper - synchronize
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this.acquire();
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PalettedContainerRO.PackedData var12;
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