Performance patches prerequisite (#2802)

Prereq changes for the coming storm of performance patches.
Includes optimising incremental saving

Spigot-Server-Patches/Fix-World-isChunkGenerated-calls.patch

@@ -8,12 +8,12 @@ This patch also adds a chunk status cache on region files (note that
 its only purpose is to cache the status on DISK)
 
 diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
-index 99ce73c45..761399e28 100644
+index 191b2759a0..9e75647953 100644
 --- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
 +++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
 @@ -0,0 +0,0 @@ public class ChunkProviderServer extends IChunkProvider {
      private final WorldServer world;
-     private final Thread serverThread;
+     public final Thread serverThread; // Paper - private -> public
      private final LightEngineThreaded lightEngine;
 -    private final ChunkProviderServer.a serverThreadQueue;
 +    public final ChunkProviderServer.a serverThreadQueue; // Paper private -> public
@@ -43,7 +43,7 @@ index 99ce73c45..761399e28 100644
  
      @Nullable
 diff --git a/src/main/java/net/minecraft/server/ChunkRegionLoader.java b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
-index 6371f2f5b..961228e9d 100644
+index 6371f2f5b1..961228e9df 100644
 --- a/src/main/java/net/minecraft/server/ChunkRegionLoader.java
 +++ b/src/main/java/net/minecraft/server/ChunkRegionLoader.java
 @@ -0,0 +0,0 @@ public class ChunkRegionLoader {
@@ -65,7 +65,7 @@ index 6371f2f5b..961228e9d 100644
          if (nbttagcompound != null) {
              ChunkStatus chunkstatus = ChunkStatus.a(nbttagcompound.getCompound("Level").getString("Status"));
 diff --git a/src/main/java/net/minecraft/server/ChunkStatus.java b/src/main/java/net/minecraft/server/ChunkStatus.java
-index efdf611e6..134a4f0b7 100644
+index efdf611e66..134a4f0b7d 100644
 --- a/src/main/java/net/minecraft/server/ChunkStatus.java
 +++ b/src/main/java/net/minecraft/server/ChunkStatus.java
 @@ -0,0 +0,0 @@ public class ChunkStatus {
@@ -95,7 +95,7 @@ index efdf611e6..134a4f0b7 100644
          return (ChunkStatus) IRegistry.CHUNK_STATUS.get(MinecraftKey.a(s));
      }
 diff --git a/src/main/java/net/minecraft/server/IChunkLoader.java b/src/main/java/net/minecraft/server/IChunkLoader.java
-index f0a052eec..2f95174fc 100644
+index f0a052eec2..2f95174fcc 100644
 --- a/src/main/java/net/minecraft/server/IChunkLoader.java
 +++ b/src/main/java/net/minecraft/server/IChunkLoader.java
 @@ -0,0 +0,0 @@ import javax.annotation.Nullable;
@@ -108,7 +108,7 @@ index f0a052eec..2f95174fc 100644
      @Nullable
      private PersistentStructureLegacy c;
 diff --git a/src/main/java/net/minecraft/server/PlayerChunk.java b/src/main/java/net/minecraft/server/PlayerChunk.java
-index 43d9a5634..6f2cca07e 100644
+index c91312facf..5108d3ee98 100644
 --- a/src/main/java/net/minecraft/server/PlayerChunk.java
 +++ b/src/main/java/net/minecraft/server/PlayerChunk.java
 @@ -0,0 +0,0 @@ public class PlayerChunk {
@@ -132,7 +132,7 @@ index 43d9a5634..6f2cca07e 100644
  
      public CompletableFuture<Either<IChunkAccess, PlayerChunk.Failure>> getStatusFutureUnchecked(ChunkStatus chunkstatus) {
 diff --git a/src/main/java/net/minecraft/server/PlayerChunkMap.java b/src/main/java/net/minecraft/server/PlayerChunkMap.java
-index 3a02b6269..6257eafe0 100644
+index 40d80f3810..6c4804232a 100644
 --- a/src/main/java/net/minecraft/server/PlayerChunkMap.java
 +++ b/src/main/java/net/minecraft/server/PlayerChunkMap.java
 @@ -0,0 +0,0 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
@@ -165,8 +165,8 @@ index 3a02b6269..6257eafe0 100644
 +        RegionFile regionFile = this.getIOWorker().getRegionFileCache().getRegionFileIfLoaded(chunkPos);
 +
 +        return regionFile == null ? null : regionFile.getStatusIfCached(chunkPos.x, chunkPos.z);
-+    }
-+
+     }
+ 
 +    public ChunkStatus getChunkStatusOnDisk(ChunkCoordIntPair chunkPos) throws IOException {
 +        RegionFile regionFile = this.getIOWorker().getRegionFileCache().getFile(chunkPos, false);
 +
@@ -194,13 +194,14 @@ index 3a02b6269..6257eafe0 100644
 +    public IChunkAccess getUnloadingChunk(int chunkX, int chunkZ) {
 +        PlayerChunk chunkHolder = this.pendingUnload.get(ChunkCoordIntPair.pair(chunkX, chunkZ));
 +        return chunkHolder == null ? null : chunkHolder.getAvailableChunkNow();
-     }
++    }
 +    // Paper end
- 
++
      boolean isOutsideOfRange(ChunkCoordIntPair chunkcoordintpair) {
          // Spigot start
+         return isOutsideOfRange(chunkcoordintpair, false);
 diff --git a/src/main/java/net/minecraft/server/RegionFile.java b/src/main/java/net/minecraft/server/RegionFile.java
-index 6b543f89d..d37abf2cf 100644
+index 6b543f89d4..d37abf2cf3 100644
 --- a/src/main/java/net/minecraft/server/RegionFile.java
 +++ b/src/main/java/net/minecraft/server/RegionFile.java
 @@ -0,0 +0,0 @@ public class RegionFile implements AutoCloseable {
@@ -249,7 +250,7 @@ index 6b543f89d..d37abf2cf 100644
              this.c();
          } finally {
 diff --git a/src/main/java/net/minecraft/server/RegionFileCache.java b/src/main/java/net/minecraft/server/RegionFileCache.java
-index b3d1bb5fd..e07ae9854 100644
+index b3d1bb5fd8..e07ae98540 100644
 --- a/src/main/java/net/minecraft/server/RegionFileCache.java
 +++ b/src/main/java/net/minecraft/server/RegionFileCache.java
 @@ -0,0 +0,0 @@ public final class RegionFileCache implements AutoCloseable {
@@ -279,7 +280,7 @@ index b3d1bb5fd..e07ae9854 100644
              throwable = throwable1;
              throw throwable1;
 diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
-index 9787d5332..f56ec3d34 100644
+index 9787d53326..f56ec3d341 100644
 --- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
 +++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
 @@ -0,0 +0,0 @@ import java.util.Objects;