Fix racey NextTickListEntry creation. (#2683)

The counter is used to distinguish entries from each other, however
since we can concurrently increment the counter we could totally
screw over the comparision of entries (see a() in NextTickListEntry),
as it compares only the time when the entry will tick, the priority
at which it will tick, and the counter. The block is not compared.

Async loading loads the chunk asynchronously which creates these
entries asynchronously.

1 files changed, 53 insertions, 31 deletions

diff --git a/Spigot-Server-Patches/0409-Asynchronous-chunk-IO-and-loading.patch b/Spigot-Server-Patches/0409-Asynchronous-chunk-IO-and-loading.patch
index 4ee7026588..5a4347fdca 100644
--- a/Spigot-Server-Patches/0409-Asynchronous-chunk-IO-and-loading.patch
+++ b/Spigot-Server-Patches/0409-Asynchronous-chunk-IO-and-loading.patch
@@ -1,4 +1,4 @@
-From 0b02a8a3a825234ca96cacba1c6ca031060bc7a0 Mon Sep 17 00:00:00 2001
+From 7245bd98a8538578656b46e9fdba082d409dc0cf Mon Sep 17 00:00:00 2001
 From: Spottedleaf <[email protected]>
 Date: Sat, 13 Jul 2019 09:23:10 -0700
 Subject: [PATCH] Asynchronous chunk IO and loading
@@ -121,7 +121,7 @@ tasks required to be executed by the chunk load task (i.e lighting
 and some poi tasks).
 
 diff --git a/src/main/java/co/aikar/timings/WorldTimingsHandler.java b/src/main/java/co/aikar/timings/WorldTimingsHandler.java
-index 3a79cde59..8de6c4816 100644
+index 3a79cde595..8de6c4816c 100644
 --- a/src/main/java/co/aikar/timings/WorldTimingsHandler.java
 +++ b/src/main/java/co/aikar/timings/WorldTimingsHandler.java
 @@ -63,6 +63,17 @@ public class WorldTimingsHandler {
@@ -161,7 +161,7 @@ index 3a79cde59..8de6c4816 100644
  
      public static Timing getTickList(WorldServer worldserver, String timingsType) {
 diff --git a/src/main/java/com/destroystokyo/paper/PaperConfig.java b/src/main/java/com/destroystokyo/paper/PaperConfig.java
-index 5942c3438..61eeb6747 100644
+index c88b5e9dd6..93c0c422da 100644
 --- a/src/main/java/com/destroystokyo/paper/PaperConfig.java
 +++ b/src/main/java/com/destroystokyo/paper/PaperConfig.java
 @@ -1,5 +1,6 @@
@@ -237,7 +237,7 @@ index 5942c3438..61eeb6747 100644
 +    }
  }
 diff --git a/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketBlockControllerAntiXray.java b/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketBlockControllerAntiXray.java
-index 23626bef3..1edcecd2e 100644
+index 23626bef3a..1edcecd2ee 100644
 --- a/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketBlockControllerAntiXray.java
 +++ b/src/main/java/com/destroystokyo/paper/antixray/ChunkPacketBlockControllerAntiXray.java
 @@ -9,6 +9,7 @@ import java.util.concurrent.Executors;
@@ -318,7 +318,7 @@ index 23626bef3..1edcecd2e 100644
  
 diff --git a/src/main/java/com/destroystokyo/paper/io/IOUtil.java b/src/main/java/com/destroystokyo/paper/io/IOUtil.java
 new file mode 100644
-index 000000000..5af0ac3d9
+index 0000000000..5af0ac3d9e
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/io/IOUtil.java
 @@ -0,0 +1,62 @@
@@ -386,7 +386,7 @@ index 000000000..5af0ac3d9
 +}
 diff --git a/src/main/java/com/destroystokyo/paper/io/PaperFileIOThread.java b/src/main/java/com/destroystokyo/paper/io/PaperFileIOThread.java
 new file mode 100644
-index 000000000..4f10a8311
+index 0000000000..4f10a8311e
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/io/PaperFileIOThread.java
 @@ -0,0 +1,661 @@
@@ -1053,7 +1053,7 @@ index 000000000..4f10a8311
 +}
 diff --git a/src/main/java/com/destroystokyo/paper/io/PrioritizedTaskQueue.java b/src/main/java/com/destroystokyo/paper/io/PrioritizedTaskQueue.java
 new file mode 100644
-index 000000000..78bd238f4
+index 0000000000..78bd238f4c
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/io/PrioritizedTaskQueue.java
 @@ -0,0 +1,276 @@
@@ -1335,7 +1335,7 @@ index 000000000..78bd238f4
 +}
 diff --git a/src/main/java/com/destroystokyo/paper/io/QueueExecutorThread.java b/src/main/java/com/destroystokyo/paper/io/QueueExecutorThread.java
 new file mode 100644
-index 000000000..ee906b594
+index 0000000000..ee906b594b
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/io/QueueExecutorThread.java
 @@ -0,0 +1,241 @@
@@ -1582,7 +1582,7 @@ index 000000000..ee906b594
 +}
 diff --git a/src/main/java/com/destroystokyo/paper/io/chunk/ChunkLoadTask.java b/src/main/java/com/destroystokyo/paper/io/chunk/ChunkLoadTask.java
 new file mode 100644
-index 000000000..305da4786
+index 0000000000..305da47868
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/io/chunk/ChunkLoadTask.java
 @@ -0,0 +1,149 @@
@@ -1737,7 +1737,7 @@ index 000000000..305da4786
 +}
 diff --git a/src/main/java/com/destroystokyo/paper/io/chunk/ChunkSaveTask.java b/src/main/java/com/destroystokyo/paper/io/chunk/ChunkSaveTask.java
 new file mode 100644
-index 000000000..60312b85f
+index 0000000000..60312b85f9
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/io/chunk/ChunkSaveTask.java
 @@ -0,0 +1,112 @@
@@ -1855,7 +1855,7 @@ index 000000000..60312b85f
 +}
 diff --git a/src/main/java/com/destroystokyo/paper/io/chunk/ChunkTask.java b/src/main/java/com/destroystokyo/paper/io/chunk/ChunkTask.java
 new file mode 100644
-index 000000000..1dfa8abfd
+index 0000000000..1dfa8abfd8
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/io/chunk/ChunkTask.java
 @@ -0,0 +1,40 @@
@@ -1901,7 +1901,7 @@ index 000000000..1dfa8abfd
 +}
 diff --git a/src/main/java/com/destroystokyo/paper/io/chunk/ChunkTaskManager.java b/src/main/java/com/destroystokyo/paper/io/chunk/ChunkTaskManager.java
 new file mode 100644
-index 000000000..59d73bfad
+index 0000000000..59d73bfad7
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/io/chunk/ChunkTaskManager.java
 @@ -0,0 +1,453 @@
@@ -2359,7 +2359,7 @@ index 000000000..59d73bfad
 +
 +}
 diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
-index 56761afdf..277c2245d 100644
+index 56761afdf4..277c2245d7 100644
 --- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
 +++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
 @@ -124,11 +124,137 @@ public class ChunkProviderServer extends IChunkProvider {
@@ -2529,7 +2529,7 @@ index 56761afdf..277c2245d 100644
          } finally {
              playerChunkMap.callbackExecutor.run();
 diff --git a/src/main/java/net/minecraft/server/ChunkRegionLoader.java b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
-index a02807411..98cc4efcf 100644
+index a028074112..98cc4efcf5 100644
 --- a/src/main/java/net/minecraft/server/ChunkRegionLoader.java
 +++ b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
 @@ -6,6 +6,7 @@ import it.unimi.dsi.fastutil.longs.LongOpenHashSet;
@@ -2798,7 +2798,7 @@ index a02807411..98cc4efcf 100644
  
          nbttagcompound1.set("PostProcessing", a(ichunkaccess.l()));
 diff --git a/src/main/java/net/minecraft/server/ChunkStatus.java b/src/main/java/net/minecraft/server/ChunkStatus.java
-index e324989b4..abb0d69d2 100644
+index e324989b46..abb0d69d2f 100644
 --- a/src/main/java/net/minecraft/server/ChunkStatus.java
 +++ b/src/main/java/net/minecraft/server/ChunkStatus.java
 @@ -153,6 +153,7 @@ public class ChunkStatus {
@@ -2810,7 +2810,7 @@ index e324989b4..abb0d69d2 100644
          return ChunkStatus.r.getInt(chunkstatus.c());
      }
 diff --git a/src/main/java/net/minecraft/server/IAsyncTaskHandler.java b/src/main/java/net/minecraft/server/IAsyncTaskHandler.java
-index d521d25cf..84024e6ba 100644
+index d521d25cf5..84024e6ba4 100644
 --- a/src/main/java/net/minecraft/server/IAsyncTaskHandler.java
 +++ b/src/main/java/net/minecraft/server/IAsyncTaskHandler.java
 @@ -91,7 +91,7 @@ public abstract class IAsyncTaskHandler<R extends Runnable> implements Mailbox<R
@@ -2823,7 +2823,7 @@ index d521d25cf..84024e6ba 100644
              ;
          }
 diff --git a/src/main/java/net/minecraft/server/IChunkLoader.java b/src/main/java/net/minecraft/server/IChunkLoader.java
-index 3f14392e6..39f6ddb1d 100644
+index 3f14392e6e..39f6ddb1d2 100644
 --- a/src/main/java/net/minecraft/server/IChunkLoader.java
 +++ b/src/main/java/net/minecraft/server/IChunkLoader.java
 @@ -3,6 +3,10 @@ package net.minecraft.server;
@@ -2895,7 +2895,7 @@ index 3f14392e6..39f6ddb1d 100644
  
      }
 diff --git a/src/main/java/net/minecraft/server/MCUtil.java b/src/main/java/net/minecraft/server/MCUtil.java
-index 23d1935dd..14f8b6104 100644
+index 23d1935dd5..14f8b61042 100644
 --- a/src/main/java/net/minecraft/server/MCUtil.java
 +++ b/src/main/java/net/minecraft/server/MCUtil.java
 @@ -530,4 +530,9 @@ public final class MCUtil {
@@ -2909,7 +2909,7 @@ index 23d1935dd..14f8b6104 100644
 +    }
  }
 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
-index 5238a1a7c..0b0058138 100644
+index 5238a1a7ca..0b00581382 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
 @@ -780,6 +780,7 @@ public abstract class MinecraftServer extends IAsyncTaskHandlerReentrant<TickTas
@@ -2920,8 +2920,30 @@ index 5238a1a7c..0b0058138 100644
      }
  
      public String getServerIp() {
+diff --git a/src/main/java/net/minecraft/server/NextTickListEntry.java b/src/main/java/net/minecraft/server/NextTickListEntry.java
+index cafb5d8830..53a290e8b5 100644
+--- a/src/main/java/net/minecraft/server/NextTickListEntry.java
++++ b/src/main/java/net/minecraft/server/NextTickListEntry.java
+@@ -4,7 +4,7 @@ import java.util.Comparator;
+ 
+ public class NextTickListEntry<T> {
+ 
+-    private static long d;
++    private static final java.util.concurrent.atomic.AtomicLong COUNTER = new java.util.concurrent.atomic.AtomicLong(); // Paper - async chunk loading
+     private final T e;
+     public final BlockPosition a;
+     public final long b;
+@@ -16,7 +16,7 @@ public class NextTickListEntry<T> {
+     }
+ 
+     public NextTickListEntry(BlockPosition blockposition, T t0, long i, TickListPriority ticklistpriority) {
+-        this.f = (long) (NextTickListEntry.d++);
++        this.f = (long) (NextTickListEntry.COUNTER.getAndIncrement()); // Paper - async chunk loading
+         this.a = blockposition.immutableCopy();
+         this.e = t0;
+         this.b = i;
 diff --git a/src/main/java/net/minecraft/server/NibbleArray.java b/src/main/java/net/minecraft/server/NibbleArray.java
-index 90c096876..eb2c06155 100644
+index 90c096876e..eb2c061550 100644
 --- a/src/main/java/net/minecraft/server/NibbleArray.java
 +++ b/src/main/java/net/minecraft/server/NibbleArray.java
 @@ -71,6 +71,7 @@ public class NibbleArray {
@@ -2933,7 +2955,7 @@ index 90c096876..eb2c06155 100644
          return this.a == null ? new NibbleArray() : new NibbleArray((byte[]) this.a.clone());
      }
 diff --git a/src/main/java/net/minecraft/server/PlayerChunk.java b/src/main/java/net/minecraft/server/PlayerChunk.java
-index af934ef8b..34d0ab0d5 100644
+index af934ef8bc..34d0ab0d5e 100644
 --- a/src/main/java/net/minecraft/server/PlayerChunk.java
 +++ b/src/main/java/net/minecraft/server/PlayerChunk.java
 @@ -310,7 +310,7 @@ public class PlayerChunk {
@@ -2959,7 +2981,7 @@ index af934ef8b..34d0ab0d5 100644
                  completablefuture = (CompletableFuture) this.statusFutures.get(i);
                  if (completablefuture != null) {
 diff --git a/src/main/java/net/minecraft/server/PlayerChunkMap.java b/src/main/java/net/minecraft/server/PlayerChunkMap.java
-index fd0d2b6e6..31d106f95 100644
+index fd0d2b6e67..31d106f951 100644
 --- a/src/main/java/net/minecraft/server/PlayerChunkMap.java
 +++ b/src/main/java/net/minecraft/server/PlayerChunkMap.java
 @@ -62,7 +62,7 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
@@ -3463,7 +3485,7 @@ index fd0d2b6e6..31d106f95 100644
          return this.n;
      }
 diff --git a/src/main/java/net/minecraft/server/RegionFile.java b/src/main/java/net/minecraft/server/RegionFile.java
-index a8c8ace46..22144eb00 100644
+index a8c8ace46c..22144eb002 100644
 --- a/src/main/java/net/minecraft/server/RegionFile.java
 +++ b/src/main/java/net/minecraft/server/RegionFile.java
 @@ -343,7 +343,7 @@ public class RegionFile implements AutoCloseable {
@@ -3476,7 +3498,7 @@ index a8c8ace46..22144eb00 100644
          this.b.close();
      }
 diff --git a/src/main/java/net/minecraft/server/RegionFileCache.java b/src/main/java/net/minecraft/server/RegionFileCache.java
-index d2b328945..d3d610742 100644
+index d2b3289450..d3d6107422 100644
 --- a/src/main/java/net/minecraft/server/RegionFileCache.java
 +++ b/src/main/java/net/minecraft/server/RegionFileCache.java
 @@ -48,13 +48,13 @@ public abstract class RegionFileCache implements AutoCloseable {
@@ -3505,7 +3527,7 @@ index d2b328945..d3d610742 100644
          RegionFile regionfile = a(pos, true);
  
 diff --git a/src/main/java/net/minecraft/server/RegionFileSection.java b/src/main/java/net/minecraft/server/RegionFileSection.java
-index 4b3e0c0f0..04b7dab64 100644
+index 4b3e0c0f01..04b7dab646 100644
 --- a/src/main/java/net/minecraft/server/RegionFileSection.java
 +++ b/src/main/java/net/minecraft/server/RegionFileSection.java
 @@ -24,7 +24,7 @@ public class RegionFileSection<R extends MinecraftSerializable> extends RegionFi
@@ -3607,7 +3629,7 @@ index 4b3e0c0f0..04b7dab64 100644
 +    // Paper end
  }
 diff --git a/src/main/java/net/minecraft/server/TicketType.java b/src/main/java/net/minecraft/server/TicketType.java
-index 9c114d2d3..e3150f85a 100644
+index 9c114d2d37..e3150f85a5 100644
 --- a/src/main/java/net/minecraft/server/TicketType.java
 +++ b/src/main/java/net/minecraft/server/TicketType.java
 @@ -22,6 +22,7 @@ public class TicketType<T> {
@@ -3619,7 +3641,7 @@ index 9c114d2d3..e3150f85a 100644
      public static <T> TicketType<T> a(String s, Comparator<T> comparator) {
          return new TicketType<>(s, comparator, 0L);
 diff --git a/src/main/java/net/minecraft/server/VillagePlace.java b/src/main/java/net/minecraft/server/VillagePlace.java
-index 316959064..0e98b7803 100644
+index 3169590641..0e98b7803b 100644
 --- a/src/main/java/net/minecraft/server/VillagePlace.java
 +++ b/src/main/java/net/minecraft/server/VillagePlace.java
 @@ -20,8 +20,16 @@ public class VillagePlace extends RegionFileSection<VillagePlaceSection> {
@@ -3708,7 +3730,7 @@ index 316959064..0e98b7803 100644
  
          HAS_SPACE(VillagePlaceRecord::d), IS_OCCUPIED(VillagePlaceRecord::e), ANY((villageplacerecord) -> {
 diff --git a/src/main/java/net/minecraft/server/WorldServer.java b/src/main/java/net/minecraft/server/WorldServer.java
-index 94df88c74..3a6745dcc 100644
+index 1330956655..5e0f6a105d 100644
 --- a/src/main/java/net/minecraft/server/WorldServer.java
 +++ b/src/main/java/net/minecraft/server/WorldServer.java
 @@ -79,6 +79,79 @@ public class WorldServer extends World {
@@ -3801,7 +3823,7 @@ index 94df88c74..3a6745dcc 100644
  
      // CraftBukkit start
 diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
-index 2227de3bf..243722b67 100644
+index 2227de3bf1..243722b672 100644
 --- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
 +++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
 @@ -554,22 +554,23 @@ public class CraftWorld implements World {
@@ -3863,7 +3885,7 @@ index 2227de3bf..243722b67 100644
      @Override
      public int getViewDistance() {
 diff --git a/src/main/java/org/spigotmc/WatchdogThread.java b/src/main/java/org/spigotmc/WatchdogThread.java
-index a1d93200e..6ca0ebfde 100644
+index a1d93200e6..6ca0ebfdee 100644
 --- a/src/main/java/org/spigotmc/WatchdogThread.java
 +++ b/src/main/java/org/spigotmc/WatchdogThread.java
 @@ -6,6 +6,7 @@ import java.lang.management.ThreadInfo;
@@ -3891,5 +3913,5 @@ index a1d93200e..6ca0ebfde 100644
                  log.log( Level.SEVERE, "------------------------------" );
                  //
 -- 
-2.23.0
+2.24.0