Paper/nms-patches/ChunkProviderServer.patch

--- a/net/minecraft/server/ChunkProviderServer.java
+++ b/net/minecraft/server/ChunkProviderServer.java
@@ -11,16 +11,27 @@
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
+// CraftBukkit start
+import java.util.Random;
+import java.util.logging.Level;
+
+import org.bukkit.Server;
+import org.bukkit.craftbukkit.chunkio.ChunkIOExecutor;
+import org.bukkit.craftbukkit.util.LongHash;
+import org.bukkit.craftbukkit.util.LongHashSet;
+import org.bukkit.craftbukkit.util.LongObjectHashMap;
+import org.bukkit.event.world.ChunkUnloadEvent;
+// CraftBukkit end
+
 public class ChunkProviderServer implements IChunkProvider {
 
     private static final Logger b = LogManager.getLogger();
-    private Set<Long> unloadQueue = Collections.newSetFromMap(new ConcurrentHashMap());
+    public LongHashSet unloadQueue = new LongHashSet(); // CraftBukkit - LongHashSet
     public Chunk emptyChunk;
     public IChunkProvider chunkProvider;
     private IChunkLoader chunkLoader;
-    public boolean forceChunkLoad = true;
-    private LongHashMap<Chunk> chunks = new LongHashMap();
-    private List<Chunk> chunkList = Lists.newArrayList();
+    public boolean forceChunkLoad = false; // CraftBukkit - true -> false
+    public LongObjectHashMap<Chunk> chunks = new LongObjectHashMap<Chunk>();
     public WorldServer world;
 
     public ChunkProviderServer(WorldServer worldserver, IChunkLoader ichunkloader, IChunkProvider ichunkprovider) {
@@ -31,26 +42,43 @@
     }
 
     public boolean isChunkLoaded(int i, int j) {
-        return this.chunks.contains(ChunkCoordIntPair.a(i, j));
+        return this.chunks.containsKey(LongHash.toLong(i, j)); // CraftBukkit
     }
 
-    public List<Chunk> a() {
-        return this.chunkList;
+    // CraftBukkit start - Change return type to Collection and return the values of our chunk map
+    public java.util.Collection a() {
+        // return this.chunkList;
+        return this.chunks.values();
+        // CraftBukkit end
     }
 
     public void queueUnload(int i, int j) {
         if (this.world.worldProvider.e()) {
             if (!this.world.c(i, j)) {
-                this.unloadQueue.add(Long.valueOf(ChunkCoordIntPair.a(i, j)));
+                // CraftBukkit start
+                this.unloadQueue.add(i, j);
+
+                Chunk c = chunks.get(LongHash.toLong(i, j));
+                if (c != null) {
+                    c.mustSave = true;
+                }
+                // CraftBukkit end
             }
         } else {
-            this.unloadQueue.add(Long.valueOf(ChunkCoordIntPair.a(i, j)));
+            // CraftBukkit start
+            this.unloadQueue.add(i, j);
+
+            Chunk c = chunks.get(LongHash.toLong(i, j));
+            if (c != null) {
+                c.mustSave = true;
+            }
+            // CraftBukkit end
         }
 
     }
 
     public void b() {
-        Iterator iterator = this.chunkList.iterator();
+        Iterator iterator = this.chunks.values().iterator();
 
         while (iterator.hasNext()) {
             Chunk chunk = (Chunk) iterator.next();
@@ -60,11 +88,48 @@
 
     }
 
+    // CraftBukkit start - Add async variant, provide compatibility
+    public Chunk getChunkIfLoaded(int x, int z) {
+        return chunks.get(LongHash.toLong(x, z));
+    }
+
     public Chunk getChunkAt(int i, int j) {
-        long k = ChunkCoordIntPair.a(i, j);
+        return getChunkAt(i, j, null);
+    }
+
+    public Chunk getChunkAt(int i, int j, Runnable runnable) {
+        unloadQueue.remove(i, j);
+        Chunk chunk = chunks.get(LongHash.toLong(i, j));
+        ChunkRegionLoader loader = null;
+
+        if (this.chunkLoader instanceof ChunkRegionLoader) {
+            loader = (ChunkRegionLoader) this.chunkLoader;
 
-        this.unloadQueue.remove(Long.valueOf(k));
-        Chunk chunk = (Chunk) this.chunks.getEntry(k);
+        }
+        // We can only use the queue for already generated chunks
+        if (chunk == null && loader != null && loader.chunkExists(world, i, j)) {
+            if (runnable != null) {
+                ChunkIOExecutor.queueChunkLoad(world, loader, this, i, j, runnable);
+                return null;
+            } else {
+                chunk = ChunkIOExecutor.syncChunkLoad(world, loader, this, i, j);
+            }
+        } else if (chunk == null) {
+            chunk = originalGetChunkAt(i, j);
+        }
+
+        // If we didn't load the chunk async and have a callback run it now
+        if (runnable != null) {
+            runnable.run();
+        }
+
+        return chunk;
+    }
+    public Chunk originalGetChunkAt(int i, int j) {
+        this.unloadQueue.remove(i, j);
+        Chunk chunk = (Chunk) this.chunks.get(LongHash.toLong(i, j));
+        boolean newChunk = false;
+        // CraftBukkit end
 
         if (chunk == null) {
             chunk = this.loadChunk(i, j);
@@ -79,16 +144,44 @@
                         CrashReportSystemDetails crashreportsystemdetails = crashreport.a("Chunk to be generated");
 
                         crashreportsystemdetails.a("Location", (Object) String.format("%d,%d", new Object[] { Integer.valueOf(i), Integer.valueOf(j)}));
-                        crashreportsystemdetails.a("Position hash", (Object) Long.valueOf(k));
+                        crashreportsystemdetails.a("Position hash", (Object) Long.valueOf(LongHash.toLong(i, j))); // CraftBukkit - Use LongHash
                         crashreportsystemdetails.a("Generator", (Object) this.chunkProvider.getName());
                         throw new ReportedException(crashreport);
                     }
                 }
+                newChunk = true; // CraftBukkit
             }
 
-            this.chunks.put(k, chunk);
-            this.chunkList.add(chunk);
+            this.chunks.put(LongHash.toLong(i, j), chunk);
+            
             chunk.addEntities();
+            
+            // CraftBukkit start
+            Server server = world.getServer();
+            if (server != null) {
+                /*
+                 * If it's a new world, the first few chunks are generated inside
+                 * the World constructor. We can't reliably alter that, so we have
+                 * no way of creating a CraftWorld/CraftServer at that point.
+                 */
+                server.getPluginManager().callEvent(new org.bukkit.event.world.ChunkLoadEvent(chunk.bukkitChunk, newChunk));
+            }
+
+            // Update neighbor counts
+            for (int x = -2; x < 3; x++) {
+                for (int z = -2; z < 3; z++) {
+                    if (x == 0 && z == 0) {
+                        continue;
+                    }
+
+                    Chunk neighbor = this.getChunkIfLoaded(chunk.locX + x, chunk.locZ + z);
+                    if (neighbor != null) {
+                        neighbor.setNeighborLoaded(-x, -z);
+                        chunk.setNeighborLoaded(x, z);
+                    }
+                }
+            }
+            // CraftBukkit end
             chunk.loadNearby(this, this, i, j);
         }
 
@@ -96,9 +189,22 @@
     }
 
     public Chunk getOrCreateChunk(int i, int j) {
-        Chunk chunk = (Chunk) this.chunks.getEntry(ChunkCoordIntPair.a(i, j));
+        // CraftBukkit start
+        Chunk chunk = (Chunk) this.chunks.get(LongHash.toLong(i, j));
+
+        chunk = chunk == null ? (!this.world.ad() && !this.forceChunkLoad ? this.emptyChunk : this.getChunkAt(i, j)) : chunk;
+
+        if (chunk == emptyChunk) return chunk;
+        if (i != chunk.locX || j != chunk.locZ) {
+            b.error("Chunk (" + chunk.locX + ", " + chunk.locZ + ") stored at  (" + i + ", " + j + ") in world '" + world.getWorld().getName() + "'");
+            b.error(chunk.getClass().getName());
+            Throwable ex = new Throwable();
+            ex.fillInStackTrace();
+            ex.printStackTrace();
+        }
 
-        return chunk == null ? (!this.world.ad() && !this.forceChunkLoad ? this.emptyChunk : this.getChunkAt(i, j)) : chunk;
+        return chunk;
+        // CraftBukkit end
     }
 
     public Chunk loadChunk(int i, int j) {
@@ -155,6 +261,30 @@
             chunk.n();
             if (this.chunkProvider != null) {
                 this.chunkProvider.getChunkAt(ichunkprovider, i, j);
+
+                // CraftBukkit start
+                BlockSand.instaFall = true;
+                Random random = new Random();
+                random.setSeed(world.getSeed());
+                long xRand = random.nextLong() / 2L * 2L + 1L;
+                long zRand = random.nextLong() / 2L * 2L + 1L;
+                random.setSeed((long) i * xRand + (long) j * zRand ^ world.getSeed());
+
+                org.bukkit.World world = this.world.getWorld();
+                if (world != null) {
+                    this.world.populating = true;
+                    try {
+                        for (org.bukkit.generator.BlockPopulator populator : world.getPopulators()) {
+                            populator.populate(world, random, chunk.bukkitChunk);
+                        }
+                    } finally {
+                        this.world.populating = false;
+                    }
+                }
+                BlockSand.instaFall = false;
+                this.world.getServer().getPluginManager().callEvent(new org.bukkit.event.world.ChunkPopulateEvent(chunk.bukkitChunk));
+                // CraftBukkit end
+                
                 chunk.e();
             }
         }
@@ -174,10 +304,12 @@
 
     public boolean saveChunks(boolean flag, IProgressUpdate iprogressupdate) {
         int i = 0;
-        ArrayList arraylist = Lists.newArrayList(this.chunkList);
 
-        for (int j = 0; j < arraylist.size(); ++j) {
-            Chunk chunk = (Chunk) arraylist.get(j);
+        // CraftBukkit start
+        Iterator iterator = this.chunks.values().iterator();
+        while (iterator.hasNext()) {
+            Chunk chunk = (Chunk) iterator.next();
+            // CraftBukkit end
 
             if (flag) {
                 this.saveChunkNOP(chunk);
@@ -205,22 +337,43 @@
 
     public boolean unloadChunks() {
         if (!this.world.savingDisabled) {
-            for (int i = 0; i < 100; ++i) {
-                if (!this.unloadQueue.isEmpty()) {
-                    Long olong = (Long) this.unloadQueue.iterator().next();
-                    Chunk chunk = (Chunk) this.chunks.getEntry(olong.longValue());
+            // CraftBukkit start
+            Server server = this.world.getServer();
+            for (int i = 0; i < 100 && !this.unloadQueue.isEmpty(); ++i) {
+                long chunkcoordinates = this.unloadQueue.popFirst();
+                Chunk chunk = this.chunks.get(chunkcoordinates);
+                if (chunk == null) continue;
+
+                ChunkUnloadEvent event = new ChunkUnloadEvent(chunk.bukkitChunk);
+                server.getPluginManager().callEvent(event);
+                if (!event.isCancelled()) {
 
                     if (chunk != null) {
                         chunk.removeEntities();
                         this.saveChunk(chunk);
                         this.saveChunkNOP(chunk);
-                        this.chunks.remove(olong.longValue());
-                        this.chunkList.remove(chunk);
+                        this.chunks.remove(chunkcoordinates); // CraftBukkit
                     }
 
-                    this.unloadQueue.remove(olong);
+                    // this.unloadQueue.remove(olong);
+
+                    // Update neighbor counts
+                    for (int x = -2; x < 3; x++) {
+                        for (int z = -2; z < 3; z++) {
+                            if (x == 0 && z == 0) {
+                                continue;
+                            }
+
+                            Chunk neighbor = this.getChunkIfLoaded(chunk.locX + x, chunk.locZ + z);
+                            if (neighbor != null) {
+                                neighbor.setNeighborUnloaded(-x, -z);
+                                chunk.setNeighborUnloaded(x, z);
+                            }
+                        }
+                    }
                 }
             }
+            // CraftBukkit end
 
             if (this.chunkLoader != null) {
                 this.chunkLoader.a();
@@ -235,7 +388,8 @@
     }
 
     public String getName() {
-        return "ServerChunkCache: " + this.chunks.count() + " Drop: " + this.unloadQueue.size();
+        // CraftBukkit - this.chunks.count() -> .size()
+        return "ServerChunkCache: " + this.chunks.size() + " Drop: " + this.unloadQueue.size();
     }
 
     public List<BiomeBase.BiomeMeta> getMobsFor(EnumCreatureType enumcreaturetype, BlockPosition blockposition) {
@@ -247,7 +401,8 @@
     }
 
     public int getLoadedChunks() {
-        return this.chunks.count();
+        // CraftBukkit - this.chunks.count() -> this.chunks.size()
+        return this.chunks.size();
     }
 
     public void recreateStructures(Chunk chunk, int i, int j) {}