Entity Tracking Ranges

This will let you configure how far to track entities in range from players, so that the entity does not render on the client if out of this range.
This has multiple benefits:

1) Less bandwidth. Not sending update packets for entities that are not even close to a player, or even close enough to clearly see.
2) Less lag by maps in item frames - Default range is 160 blocks... Many players can track that item frame and cause lag and not even see it.
3) Less lag in general - Less work for the server to do
4) Less client lag - Not trying to render distant item frames and paintings and entities will reduce entity count on the client, which is major for shop/town worlds which may use tons of item frames.

By: Aikar <aikar@aikar.co>

paper-server/patches/sources/net/minecraft/server/level/ChunkMap.java.patch

@@ -11,10 +11,11 @@
  public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider, GeneratingChunkMap {
  
      private static final ChunkResult<List<ChunkAccess>> UNLOADED_CHUNK_LIST_RESULT = ChunkResult.error("Unloaded chunks found in range");
-@@ -149,6 +153,27 @@
+@@ -148,6 +152,27 @@
+     private final AtomicInteger activeChunkWrites;
      public int serverViewDistance;
      private final WorldGenContext worldGenContext;
- 
++
 +    // CraftBukkit start - recursion-safe executor for Chunk loadCallback() and unloadCallback()
 +    public final CallbackExecutor callbackExecutor = new CallbackExecutor();
 +    public static final class CallbackExecutor implements java.util.concurrent.Executor, Runnable {
@@ -35,10 +36,9 @@
 +        }
 +    };
 +    // CraftBukkit end
-+
+ 
      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(new RegionStorageInfo(session.getLevelId(), world.dimension(), "chunk"), session.getDimensionPath(world.dimension()).resolve("region"), dataFixer, dsync);
-         this.visibleChunkMap = this.updatingChunkMap.clone();
 @@ -170,7 +195,13 @@
          RegistryAccess iregistrycustom = world.registryAccess();
          long j = world.getSeed();
@@ -165,7 +165,7 @@
          }
      }
  
-@@ -1215,6 +1266,7 @@
+@@ -1215,9 +1266,11 @@
      }
  
      public void addEntity(Entity entity) {
@@ -173,7 +173,11 @@
          if (!(entity instanceof EnderDragonPart)) {
              EntityType<?> entitytypes = entity.getType();
              int i = entitytypes.clientTrackingRange() * 16;
-@@ -1250,6 +1302,7 @@
++            i = org.spigotmc.TrackingRange.getEntityTrackingRange(entity, i); // Spigot
+ 
+             if (i != 0) {
+                 int j = entitytypes.updateInterval();
+@@ -1250,6 +1303,7 @@
      }
  
      protected void removeEntity(Entity entity) {
@@ -181,7 +185,7 @@
          if (entity instanceof ServerPlayer entityplayer) {
              this.updatePlayerStatus(entityplayer, false);
              ObjectIterator objectiterator = this.entityMap.values().iterator();
-@@ -1424,7 +1477,7 @@
+@@ -1424,7 +1478,7 @@
          public final Set<ServerPlayerConnection> seenBy = Sets.newIdentityHashSet();
  
          public TrackedEntity(final Entity entity, final int i, final int j, final boolean flag) {
@@ -190,7 +194,7 @@
              this.entity = entity;
              this.range = i;
              this.lastSectionPos = SectionPos.of((EntityAccess) entity);
-@@ -1469,6 +1522,7 @@
+@@ -1469,6 +1523,7 @@
          }
  
          public void removePlayer(ServerPlayer player) {
@@ -198,7 +202,7 @@
              if (this.seenBy.remove(player.connection)) {
                  this.serverEntity.removePairing(player);
              }
-@@ -1476,6 +1530,7 @@
+@@ -1476,6 +1531,7 @@
          }
  
          public void updatePlayer(ServerPlayer player) {
@@ -206,7 +210,7 @@
              if (player != this.entity) {
                  Vec3 vec3d = player.position().subtract(this.entity.position());
                  int i = ChunkMap.this.getPlayerViewDistance(player);
-@@ -1484,6 +1539,11 @@
+@@ -1484,6 +1540,11 @@
                  double d2 = d0 * d0;
                  boolean flag = d1 <= d2 && this.entity.broadcastToPlayer(player) && ChunkMap.this.isChunkTracked(player, this.entity.chunkPosition().x, this.entity.chunkPosition().z);