PaperMC/patches/removed/1.19.2-legacy-chunksystem/0015-Do-not-copy-visible-chunks.patch
Spottedleaf 01a13871de
Rewrite chunk system (#8177)
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.
2022-09-26 01:02:51 -07:00

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Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Sun, 21 Mar 2021 11:22:10 -0700
Subject: [PATCH] Do not copy visible chunks
For servers with a lot of chunk holders, copying for each
tickDistanceManager call can take up quite a bit in
the function. I saw approximately 1/3rd of the function
on the copy.
diff --git a/src/main/java/net/minecraft/server/ChunkSystem.java b/src/main/java/net/minecraft/server/ChunkSystem.java
index 83dc09f6526206690c474b50a7a6e71cefc93ab4..7f76c304f5eb3c2f27b348918588ab67b795b1ba 100644
--- a/src/main/java/net/minecraft/server/ChunkSystem.java
+++ b/src/main/java/net/minecraft/server/ChunkSystem.java
@@ -202,19 +202,24 @@ public final class ChunkSystem {
}
public static List<ChunkHolder> getVisibleChunkHolders(final ServerLevel level) {
- return new ArrayList<>(level.chunkSource.chunkMap.visibleChunkMap.values());
+ if (Bukkit.isPrimaryThread()) {
+ return level.chunkSource.chunkMap.updatingChunks.getVisibleValuesCopy();
+ }
+ synchronized (level.chunkSource.chunkMap.updatingChunks) {
+ return level.chunkSource.chunkMap.updatingChunks.getVisibleValuesCopy();
+ }
}
public static List<ChunkHolder> getUpdatingChunkHolders(final ServerLevel level) {
- return new ArrayList<>(level.chunkSource.chunkMap.updatingChunkMap.values());
+ return level.chunkSource.chunkMap.updatingChunks.getUpdatingValuesCopy();
}
public static int getVisibleChunkHolderCount(final ServerLevel level) {
- return level.chunkSource.chunkMap.visibleChunkMap.size();
+ return level.chunkSource.chunkMap.updatingChunks.getVisibleMap().size();
}
public static int getUpdatingChunkHolderCount(final ServerLevel level) {
- return level.chunkSource.chunkMap.updatingChunkMap.size();
+ return level.chunkSource.chunkMap.updatingChunks.getUpdatingMap().size();
}
public static boolean hasAnyChunkHolders(final ServerLevel level) {
diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
index 2a9e5fb8164f79b0f9c1cb5497216e51f9df3454..ea27e6b1340a42c675bc68ed75f100569114be7a 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -121,9 +121,11 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
private static final int MIN_VIEW_DISTANCE = 3;
public static final int MAX_VIEW_DISTANCE = 33;
public static final int MAX_CHUNK_DISTANCE = 33 + ChunkStatus.maxDistance();
+ // Paper start - Don't copy
+ public final com.destroystokyo.paper.util.map.QueuedChangesMapLong2Object<ChunkHolder> updatingChunks = new com.destroystokyo.paper.util.map.QueuedChangesMapLong2Object<>();
+ // Paper end - Don't copy
public static final int FORCED_TICKET_LEVEL = 31;
- public final Long2ObjectLinkedOpenHashMap<ChunkHolder> updatingChunkMap = new Long2ObjectLinkedOpenHashMap();
- public volatile Long2ObjectLinkedOpenHashMap<ChunkHolder> visibleChunkMap;
+ // Paper - Don't copy
private final Long2ObjectLinkedOpenHashMap<ChunkHolder> pendingUnloads;
public final LongSet entitiesInLevel;
public final ServerLevel level;
@@ -224,7 +226,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
public ChunkMap(ServerLevel world, LevelStorageSource.LevelStorageAccess session, DataFixer dataFixer, StructureTemplateManager structureTemplateManager, Executor executor, BlockableEventLoop<Runnable> mainThreadExecutor, LightChunkGetter chunkProvider, ChunkGenerator chunkGenerator, ChunkProgressListener worldGenerationProgressListener, ChunkStatusUpdateListener chunkStatusChangeListener, Supplier<DimensionDataStorage> persistentStateManagerFactory, int viewDistance, boolean dsync) {
super(session.getDimensionPath(world.dimension()).resolve("region"), dataFixer, dsync);
- this.visibleChunkMap = this.updatingChunkMap.clone();
+ // Paper - don't copy
this.pendingUnloads = new Long2ObjectLinkedOpenHashMap();
this.entitiesInLevel = new LongOpenHashSet();
this.toDrop = new LongOpenHashSet();
@@ -327,12 +329,17 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
@Nullable
public ChunkHolder getUpdatingChunkIfPresent(long pos) {
- return (ChunkHolder) this.updatingChunkMap.get(pos);
+ return this.updatingChunks.getUpdating(pos); // Paper - Don't copy
}
@Nullable
public ChunkHolder getVisibleChunkIfPresent(long pos) {
- return (ChunkHolder) this.visibleChunkMap.get(pos);
+ // Paper start - Don't copy
+ if (Thread.currentThread() == this.level.thread) {
+ return this.updatingChunks.getVisible(pos);
+ }
+ return this.updatingChunks.getVisibleAsync(pos);
+ // Paper end - Don't copy
}
protected IntSupplier getChunkQueueLevel(long pos) {
@@ -515,7 +522,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
// Paper start
holder.onChunkAdd();
// Paper end
- this.updatingChunkMap.put(pos, holder);
+ this.updatingChunks.queueUpdate(pos, holder); // Paper - Don't copy
this.modified = true;
}
@@ -592,7 +599,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
for (int i = 0; longiterator.hasNext() && (shouldKeepTicking.getAsBoolean() || i < 200 || this.toDrop.size() > 2000); longiterator.remove()) {
long j = longiterator.nextLong();
- ChunkHolder playerchunk = (ChunkHolder) this.updatingChunkMap.remove(j);
+ ChunkHolder playerchunk = this.updatingChunks.queueRemove(j); // Paper - Don't copy
if (playerchunk != null) {
playerchunk.onChunkRemove(); // Paper
@@ -672,7 +679,12 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
if (!this.modified) {
return false;
} else {
- this.visibleChunkMap = this.updatingChunkMap.clone();
+ // Paper start - Don't copy
+ synchronized (this.updatingChunks) {
+ this.updatingChunks.performUpdates();
+ }
+ // Paper end - Don't copy
+
this.modified = false;
return true;
}