From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sat, 12 Sep 2020 22:20:55 -0400
Subject: [PATCH] Only consider chunks Loaded if at BORDER status

This greatly improves performance as it drastically reduces the amount
of Entities and Tile Entities that are "registered" into the world, as
purely "cached" chunks will no longer have their entities hanging out in the world.

Additionally this fixes our Entity Add To World and Entity Remove From World events

Those events have not been firing correctly since MC changed how chunks work here.

Now the server will only consider a chunk "loaded" if it's got a ticket putting
it at level 33 or lower, which matches the public Bukkit API.

diff --git a/src/main/java/net/minecraft/server/Chunk.java b/src/main/java/net/minecraft/server/Chunk.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/server/Chunk.java
+++ b/src/main/java/net/minecraft/server/Chunk.java
@@ -0,0 +0,0 @@ public class Chunk implements IChunkAccess {
         int chunkX = this.loc.x;
         int chunkZ = this.loc.z;
         ChunkProviderServer chunkProvider = ((WorldServer)this.world).getChunkProvider();
+        chunkProvider.playerChunkMap.loadChunk(this); // Paper - move load logic from the entering full status to when it enters border status instead
         for (int dx = -NEIGHBOUR_CACHE_RADIUS; dx <= NEIGHBOUR_CACHE_RADIUS; ++dx) {
             for (int dz = -NEIGHBOUR_CACHE_RADIUS; dz <= NEIGHBOUR_CACHE_RADIUS; ++dz) {
                 Chunk neighbour = chunkProvider.getChunkAtIfLoadedMainThreadNoCache(chunkX + dx, chunkZ + dz);
@@ -0,0 +0,0 @@ public class Chunk implements IChunkAccess {
         this.loadedTicketLevel = false;
         this.resetNeighbours();
         // Paper end
+        // Paper start - move unload logic from the actual full unload to be when it leaves border status
+        chunkProvider.playerChunkMap.loadedChunks.remove(loc.longKey);
+        setLoaded(false);
+        this.world.unloadChunk(this);
+        // Paper end
     }
     // CraftBukkit end
 
diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
+++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
@@ -0,0 +0,0 @@ import java.util.function.Supplier;
 import javax.annotation.Nullable;
 import com.destroystokyo.paper.exception.ServerInternalException;
 import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap; // Paper
+import it.unimi.dsi.fastutil.longs.LongIterator; // Paper
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
@@ -0,0 +0,0 @@ public class ChunkProviderServer extends IChunkProvider {
             //List<PlayerChunk> list = Lists.newArrayList(this.playerChunkMap.f()); // Paper
             //Collections.shuffle(list); // Paper
             // Paper - moved up
-            final int[] chunksTicked = {0}; this.playerChunkMap.forEachVisibleChunk((playerchunk) -> { // Paper - safe iterator incase chunk loads, also no wrapping
+            final int[] chunksTicked = {0};
+            this.playerChunkMap.forEachVisibleChunk((playerchunk) -> {
+            //for (LongIterator iterator = this.playerChunkMap.loadedChunks.iterator() ; iterator.hasNext() ; ) { // Paper - iterate only loaded chunks
+                //PlayerChunk playerchunk = this.playerChunkMap.getVisibleChunk(iterator.nextLong());// Paper - iterate only loaded chunks
                 Optional<Chunk> optional = ((Either) playerchunk.a().getNow(PlayerChunk.UNLOADED_CHUNK)).left();
 
                 if (optional.isPresent()) {
@@ -0,0 +0,0 @@ public class ChunkProviderServer extends IChunkProvider {
                         }
                     }
                 }
-            });
+            });// Paper - use for instead of forEachVisibleChunk
             this.world.getMethodProfiler().enter("customSpawners");
             if (flag1) {
                 try (co.aikar.timings.Timing ignored = this.world.timings.miscMobSpawning.startTiming()) { // Paper - timings
diff --git a/src/main/java/net/minecraft/server/PlayerChunkMap.java b/src/main/java/net/minecraft/server/PlayerChunkMap.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 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 {
                 this.a(i, playerchunk);
             } else {
                 if (this.pendingUnload.remove(i, playerchunk) && ichunkaccess != null) {
+                    // Paper start - coment out and move to ChunkUnloadEvent
                     if (ichunkaccess instanceof Chunk) {
-                        ((Chunk) ichunkaccess).setLoaded(false);
+                        //((Chunk) ichunkaccess).setLoaded(false);
                     }
 
                     //this.saveChunk(ichunkaccess);// Paper - delay
-                    if (this.loadedChunks.remove(i) && ichunkaccess instanceof Chunk) {
-                        Chunk chunk = (Chunk) ichunkaccess;
-
-                        this.world.unloadChunk(chunk);
-                    }
+//                    if (this.loadedChunks.remove(i) && ichunkaccess instanceof Chunk) {
+//                        Chunk chunk = (Chunk) ichunkaccess;
+//
+//                        this.world.unloadChunk(chunk);
+//                    }
+                    // Paper end
                     this.autoSaveQueue.remove(playerchunk); // Paper
 
                     try {
@@ -0,0 +0,0 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
                     return PlayerChunk.getChunkState(playerchunk.getTicketLevel());
                 });
                 chunk.addEntities();
+                // Paper start
+                return chunk;
+            } // Paper
+            });
+        }, (runnable) -> {
+
+            this.mailboxMain.a(ChunkTaskQueueSorter.a(runnable, playerchunk.i().pair(), () -> 1)); // Paper - final loads are always urgent!
+        });
+    }
+    public void loadChunk(Chunk chunk) {
+        if (true) {
+            if (true) {
+                ChunkCoordIntPair chunkcoordintpair = chunk.getPos();
+                // Paper end
                 if (this.loadedChunks.add(chunkcoordintpair.pair())) {
                     chunk.setLoaded(true);
                     this.world.a(chunk.getTileEntities().values());
@@ -0,0 +0,0 @@ public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
                         list.forEach(chunk::b);
                     }
                 }
-
-                return chunk;
-                } // Paper
-            });
-        }, (runnable) -> {
-            Mailbox mailbox = this.mailboxMain;
-            long i = playerchunk.i().pair();
-
-            playerchunk.getClass();
-            mailbox.a(ChunkTaskQueueSorter.a(runnable, i, () -> 1)); // Paper - final loads are always urgent!
-        });
+                // Paper start
+            }
+        }
+        // Move code up
+//                return chunk;
+//                } // Paper
+//            });
+//        }, (runnable) -> {
+//            Mailbox mailbox = this.mailboxMain;
+//            long i = playerchunk.i().pair();
+//
+//            playerchunk.getClass();
+//            mailbox.a(ChunkTaskQueueSorter.a(runnable, i, () -> 1)); // Paper - final loads are always urgent!
+//        });
+        // Paper end
     }
 
     // Paper start