SPIGOT-2439: Consistently fire Chunk(Load|Unload)Event

Clean up implementation and firing of both of these events by routing
both unload and load behaviors to consistent method calls.

This fixes issues where a few places would not call Load or Unload events
when it should have.

Additionally, reduces diff by moving the neighbor marking code into these
consistent points.

Additional benefits of the change include improving the neighbor marking
methods to use getChunkIfLoaded instead of getLoadedChunkAt in some places,
as the latter will cause chunks to be marked active and not unload.

Finally, this also updates CraftWorld.loadChunk to use the new methods, as the
previous logic did not properly handle the new unload queue.

4 files changed, 135 insertions, 163 deletions

diff --git a/nms-patches/Chunk.patch b/nms-patches/Chunk.patch
index 3c963755..5a5ad49b 100644
--- a/nms-patches/Chunk.patch
+++ b/nms-patches/Chunk.patch
@@ -5,17 +5,18 @@
  import org.apache.logging.log4j.Logger;
  
 +import com.google.common.collect.Lists; // CraftBukkit
-+import org.bukkit.Bukkit; // CraftBukkit
++import org.bukkit.Server; // CraftBukkit
 +
  public class Chunk {
  
      private static final Logger e = LogManager.getLogger();
-@@ -42,6 +45,34 @@
+@@ -42,6 +45,35 @@
      private ConcurrentLinkedQueue<BlockPosition> y;
      public boolean d;
  
 +    // CraftBukkit start - Neighbor loaded cache for chunk lighting and entity ticking
 +    private int neighbors = 0x1 << 12;
++    public long chunkKey;
 +
 +    public boolean areNeighborsLoaded(final int radius) {
 +        switch (radius) {
@@ -45,12 +46,13 @@
      public Chunk(World world, int i, int j) {
          this.sections = new ChunkSection[16];
          this.g = new byte[256];
-@@ -62,8 +93,14 @@
+@@ -62,8 +94,15 @@
  
          Arrays.fill(this.h, -999);
          Arrays.fill(this.g, (byte) -1);
 +        // CraftBukkit start
 +        this.bukkitChunk = new org.bukkit.craftbukkit.CraftChunk(this);
++        this.chunkKey = ChunkCoordIntPair.a(this.locX, this.locZ);
      }
  
 +    public org.bukkit.Chunk bukkitChunk;
@@ -60,7 +62,7 @@
      public Chunk(World world, ChunkSnapshot chunksnapshot, int i, int j) {
          this(world, i, j);
          boolean flag = true;
-@@ -467,7 +504,8 @@
+@@ -467,7 +506,8 @@
                      }
                  }
  
@@ -70,7 +72,7 @@
                      block.onPlace(this.world, blockposition, iblockdata);
                  }
  
-@@ -604,7 +642,15 @@
+@@ -604,7 +644,15 @@
  
      @Nullable
      public TileEntity a(BlockPosition blockposition, Chunk.EnumTileEntityState chunk_enumtileentitystate) {
@@ -87,7 +89,7 @@
  
          if (tileentity == null) {
              if (chunk_enumtileentitystate == Chunk.EnumTileEntityState.IMMEDIATE) {
-@@ -639,6 +685,13 @@
+@@ -639,6 +687,13 @@
  
              tileentity.z();
              this.tileEntities.put(blockposition, tileentity);
@@ -101,7 +103,7 @@
          }
      }
  
-@@ -681,9 +734,21 @@
+@@ -681,9 +736,21 @@
          int i = aentityslice.length;
  
          for (int j = 0; j < i; ++j) {
@@ -111,21 +113,21 @@
 +            java.util.Iterator<Entity> iter = newList.iterator();
 +            while (iter.hasNext()) {
 +                Entity entity = iter.next();
- 
--            this.world.c((Collection) entityslice);
++
 +                // Do not pass along players, as doing so can get them stuck outside of time.
 +                // (which for example disables inventory icon updates and prevents block breaking)
 +                if (entity instanceof EntityPlayer) {
 +                    iter.remove();
 +                }
 +            }
-+
-+            this.world.c((Collection) newList);
+ 
+-            this.world.c((Collection) entityslice);
++            this.world.c(newList);
 +            // CraftBukkit end
          }
  
      }
-@@ -745,8 +810,8 @@
+@@ -745,8 +812,8 @@
              while (iterator.hasNext()) {
                  Entity entity = (Entity) iterator.next();
  
@@ -136,7 +138,43 @@
                  }
              }
          }
-@@ -809,6 +874,29 @@
+@@ -773,7 +840,34 @@
+         return false;
+     }
+ 
+-    public void loadNearby(IChunkProvider ichunkprovider, ChunkGenerator chunkgenerator) {
++    // CraftBukkit start
++    public void loadNearby(IChunkProvider ichunkprovider, ChunkGenerator chunkgenerator, boolean newChunk) {
++        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(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 = getWorld().getChunkIfLoaded(locX + x, locZ + z);
++                if (neighbor != null) {
++                    neighbor.setNeighborLoaded(-x, -z);
++                    setNeighborLoaded(x, z);
++                }
++            }
++        }
++        // CraftBukkit end
++
+         Chunk chunk = ichunkprovider.getLoadedChunkAt(this.locX, this.locZ - 1);
+         Chunk chunk1 = ichunkprovider.getLoadedChunkAt(this.locX + 1, this.locZ);
+         Chunk chunk2 = ichunkprovider.getLoadedChunkAt(this.locX, this.locZ + 1);
+@@ -809,6 +903,29 @@
          } else {
              this.o();
              chunkgenerator.recreateStructures(this.locX, this.locZ);
diff --git a/nms-patches/ChunkProviderServer.patch b/nms-patches/ChunkProviderServer.patch
index f6fa24c8..bb34c203 100644
--- a/nms-patches/ChunkProviderServer.patch
+++ b/nms-patches/ChunkProviderServer.patch
@@ -1,11 +1,10 @@
 --- a/net/minecraft/server/ChunkProviderServer.java
 +++ b/net/minecraft/server/ChunkProviderServer.java
-@@ -14,6 +14,12 @@
+@@ -14,6 +14,11 @@
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  
 +// CraftBukkit start
-+import org.bukkit.Server;
 +import org.bukkit.craftbukkit.chunkio.ChunkIOExecutor;
 +import org.bukkit.event.world.ChunkUnloadEvent;
 +// CraftBukkit end
@@ -13,7 +12,7 @@
  public class ChunkProviderServer implements IChunkProvider {
  
      private static final Logger a = LogManager.getLogger();
-@@ -69,6 +75,26 @@
+@@ -69,19 +74,82 @@
          Chunk chunk = this.getLoadedChunkAt(i, j);
  
          if (chunk == null) {
@@ -40,7 +39,12 @@
              chunk = this.loadChunk(i, j);
              if (chunk != null) {
                  this.chunks.put(ChunkCoordIntPair.a(i, j), chunk);
-@@ -80,8 +106,52 @@
+                 chunk.addEntities();
+-                chunk.loadNearby(this, this.chunkGenerator);
++                chunk.loadNearby(this, this.chunkGenerator, false); // CraftBukkit
+             }
+         }
+ 
          return chunk;
      }
  
@@ -89,50 +93,21 @@
 +
 +    public Chunk originalGetChunkAt(int i, int j) {
 +        Chunk chunk = this.originalGetOrLoadChunkAt(i, j);
-+        boolean newChunk = false;
 +        // CraftBukkit end
  
          if (chunk == null) {
              long k = ChunkCoordIntPair.a(i, j);
-@@ -97,9 +167,37 @@
-                 crashreportsystemdetails.a("Generator", (Object) this.chunkGenerator);
-                 throw new ReportedException(crashreport);
-             }
-+            newChunk = true; // CraftBukkit
+@@ -100,7 +168,8 @@
  
              this.chunks.put(k, chunk);
              chunk.addEntities();
+-            chunk.loadNearby(this, this.chunkGenerator);
 +
-+            // 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.chunkGenerator);
++            chunk.loadNearby(this, this.chunkGenerator, true); // CraftBukkit
          }
  
-@@ -146,10 +244,12 @@
+         return chunk;
+@@ -146,10 +215,12 @@
  
      public boolean a(boolean flag) {
          int i = 0;
@@ -148,33 +123,60 @@
  
              if (flag) {
                  this.saveChunkNOP(chunk);
-@@ -182,6 +282,29 @@
+@@ -182,10 +253,12 @@
                      Chunk chunk = (Chunk) this.chunks.get(olong);
  
                      if (chunk != null && chunk.d) {
-+                        // CraftBukkit start
-+                        ChunkUnloadEvent event = new ChunkUnloadEvent(chunk.bukkitChunk);
-+                        this.world.getServer().getPluginManager().callEvent(event);
-+                        if (event.isCancelled()) {
+-                        chunk.removeEntities();
+-                        this.saveChunk(chunk);
+-                        this.saveChunkNOP(chunk);
+-                        this.chunks.remove(olong);
++                        // CraftBukkit start - move unload logic to own method
++                        if (!unloadChunk(chunk, true)) {
 +                            continue;
 +                        }
-+
-+                        // 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
 +
-                         chunk.removeEntities();
-                         this.saveChunk(chunk);
-                         this.saveChunkNOP(chunk);
+                         ++i;
+                     }
+                 }
+@@ -197,6 +270,39 @@
+         return false;
+     }
+ 
++    // CraftBukkit start
++    public boolean unloadChunk(Chunk chunk, boolean save) {
++        ChunkUnloadEvent event = new ChunkUnloadEvent(chunk.bukkitChunk);
++        this.world.getServer().getPluginManager().callEvent(event);
++        if (event.isCancelled()) {
++            return false;
++        }
++
++        // 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);
++                }
++            }
++        }
++        // Moved from unloadChunks above
++        chunk.removeEntities();
++        if (save) {
++            this.saveChunk(chunk);
++            this.saveChunkNOP(chunk);
++        }
++        this.chunks.remove(chunk.chunkKey);
++        return true;
++    }
++    // CraftBukkit end
++
+     public boolean e() {
+         return !this.world.savingDisabled;
+     }
diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
index 3ee0b91e..2fe3eae8 100644
--- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
@@ -187,47 +187,26 @@ public class CraftWorld implements World {
             return false;
         }
 
-        return unloadChunk0(x, z, save, safe);
+        return unloadChunk0(x, z, save);
     }
 
-    private boolean unloadChunk0(int x, int z, boolean save, boolean safe) {
-        net.minecraft.server.Chunk chunk = world.getChunkProviderServer().getChunkAt(x, z);
-        if (chunk.mustSave) {   // If chunk had previously been queued to save, must do save to avoid loss of that data
-            save = true;
-        }
-
-        chunk.removeEntities(); // Always remove entities - even if discarding, need to get them out of world table
-
-        if (save) {
-            world.getChunkProviderServer().saveChunk(chunk);
-            world.getChunkProviderServer().saveChunkNOP(chunk);
-        }
-
-        world.getChunkProviderServer().unloadQueue.remove(ChunkCoordIntPair.a(x, z));
-        world.getChunkProviderServer().chunks.remove(ChunkCoordIntPair.a(x, z));
-
-        // Update neighbor counts
-        for (int xx = -2; xx < 3; xx++) {
-            for (int zz = -2; zz < 3; zz++) {
-                if (xx == 0 && zz == 0) {
-                    continue;
-                }
-
-                net.minecraft.server.Chunk neighbor = world.getChunkProviderServer().getChunkIfLoaded(chunk.locX + x, chunk.locZ + z);
-                if (neighbor != null) {
-                    neighbor.setNeighborUnloaded(-xx, -zz);
-                    chunk.setNeighborUnloaded(xx, zz);
-                }
-            }
+    private boolean unloadChunk0(int x, int z, boolean save) {
+        net.minecraft.server.Chunk chunk = world.getChunkProviderServer().getChunkIfLoaded(x, z);
+        if (chunk == null) {
+            return true;
         }
 
-        return true;
+        // If chunk had previously been queued to save, must do save to avoid loss of that data
+        return world.getChunkProviderServer().unloadChunk(chunk, chunk.mustSave || save);
     }
 
     public boolean regenerateChunk(int x, int z) {
-        unloadChunk0(x, z, false, false);
+        if (!unloadChunk0(x, z, false)) {
+            return false;
+        }
 
-        world.getChunkProviderServer().unloadQueue.remove(ChunkCoordIntPair.a(x, z));
+        final long chunkKey = ChunkCoordIntPair.a(x, z);
+        world.getChunkProviderServer().unloadQueue.remove(chunkKey);
 
         net.minecraft.server.Chunk chunk = null;
 
@@ -237,9 +216,14 @@ public class CraftWorld implements World {
             playerChunk.chunk = chunk;
         }
 
-        chunkLoadPostProcess(chunk, x, z);
+        if (chunk != null) {
+            world.getChunkProviderServer().chunks.put(chunkKey, chunk);
 
-        refreshChunk(x, z);
+            chunk.addEntities();
+            chunk.loadNearby(world.getChunkProviderServer(), world.getChunkProviderServer().chunkGenerator, true);
+
+            refreshChunk(x, z);
+        }
 
         return chunk != null;
     }
@@ -275,39 +259,7 @@ public class CraftWorld implements World {
             return world.getChunkProviderServer().getChunkAt(x, z) != null;
         }
 
-        world.getChunkProviderServer().unloadQueue.remove(ChunkCoordIntPair.a(x, z));
-        net.minecraft.server.Chunk chunk = world.getChunkProviderServer().chunks.get(ChunkCoordIntPair.a(x, z));
-
-        if (chunk == null) {
-            chunk = world.getChunkProviderServer().getOrLoadChunkAt(x, z);
-        }
-        return chunk != null;
-    }
-
-    private void chunkLoadPostProcess(net.minecraft.server.Chunk chunk, int cx, int cz) {
-        if (chunk != null) {
-            world.getChunkProviderServer().chunks.put(ChunkCoordIntPair.a(cx, cz), chunk);
-
-            chunk.addEntities();
-
-            // Update neighbor counts
-            for (int x = -2; x < 3; x++) {
-                for (int z = -2; z < 3; z++) {
-                    if (x == 0 && z == 0) {
-                        continue;
-                    }
-
-                    net.minecraft.server.Chunk neighbor = world.getChunkProviderServer().getLoadedChunkAt(chunk.locX + x, chunk.locZ + z);
-                    if (neighbor != null) {
-                        neighbor.setNeighborLoaded(-x, -z);
-                        chunk.setNeighborLoaded(x, z);
-                    }
-                }
-            }
-            // CraftBukkit end
-
-            chunk.loadNearby(world.getChunkProviderServer(), world.getChunkProviderServer().chunkGenerator);
-        }
+        return world.getChunkProviderServer().getOrLoadChunkAt(x, z) != null;
     }
 
     public boolean isChunkLoaded(Chunk chunk) {
diff --git a/src/main/java/org/bukkit/craftbukkit/chunkio/ChunkIOProvider.java b/src/main/java/org/bukkit/craftbukkit/chunkio/ChunkIOProvider.java
index 1632f136..f1c1dc49 100644
--- a/src/main/java/org/bukkit/craftbukkit/chunkio/ChunkIOProvider.java
+++ b/src/main/java/org/bukkit/craftbukkit/chunkio/ChunkIOProvider.java
@@ -48,27 +48,7 @@ class ChunkIOProvider implements AsynchronousExecutor.CallBackProvider<QueuedChu
             queuedChunk.provider.chunkGenerator.recreateStructures(chunk, queuedChunk.x, queuedChunk.z);
         }
 
-        Server server = queuedChunk.provider.world.getServer();
-        if (server != null) {
-            server.getPluginManager().callEvent(new org.bukkit.event.world.ChunkLoadEvent(chunk.bukkitChunk, false));
-        }
-
-        // 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 = queuedChunk.provider.getLoadedChunkAt(chunk.locX + x, chunk.locZ + z);
-                if (neighbor != null) {
-                    neighbor.setNeighborLoaded(-x, -z);
-                    chunk.setNeighborLoaded(x, z);
-                }
-            }
-        }
-
-        chunk.loadNearby(queuedChunk.provider, queuedChunk.provider.chunkGenerator);
+        chunk.loadNearby(queuedChunk.provider, queuedChunk.provider.chunkGenerator, false);
     }
 
     public void callStage3(QueuedChunk queuedChunk, Chunk chunk, Runnable runnable) throws RuntimeException {