rewrite chunk system checkpoint

patches/server/Allow-Saving-of-Oversized-Chunks.patch

@@ -50,9 +50,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
  import org.slf4j.Logger;
  
 @@ -0,0 +0,0 @@ public class RegionFile implements AutoCloseable {
-     private final IntBuffer timestamps;
      @VisibleForTesting
      protected final RegionBitmap usedSectors;
+     public final java.util.concurrent.locks.ReentrantLock fileLock = new java.util.concurrent.locks.ReentrantLock(true); // Paper
 +    public final Path regionFile; // Paper
  
      public RegionFile(Path file, Path directory, boolean dsync) throws IOException {
@@ -229,7 +229,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
      public CompoundTag read(ChunkPos pos) throws IOException {
          // CraftBukkit start - SPIGOT-5680: There's no good reason to preemptively create files on read, save that for writing
 @@ -0,0 +0,0 @@ public class RegionFileStorage implements AutoCloseable {
-         // CraftBukkit end
+         try { // Paper
          DataInputStream datainputstream = regionfile.getChunkDataInputStream(pos);
  
 +        // Paper start