ChunkProcessor auto trim and chunk unloading

- The auto trim drastically reduces the cost of players exploring on
speed 10, as it prevents chunks of unowned plots from saving to disk
when the chunk is unloaded
- It is recommended to disable world auto saving, or also enable the
chunk processor GC, as otherwise minecraft will also save chunks as they
are loaded.

src/main/java/com/intellectualcrafters/plot/PS.java

@@ -1838,6 +1838,8 @@ public class PS {
         
         // Chunk processor
         options.put("chunk-processor.enabled", Settings.CHUNK_PROCESSOR);
+        options.put("chunk-processor.auto-unload", Settings.CHUNK_PROCESSOR_GC);
+        options.put("chunk-processor.auto-trim", Settings.CHUNK_PROCESSOR_TRIM_ON_SAVE);
         options.put("chunk-processor.max-blockstates", Settings.CHUNK_PROCESSOR_MAX_BLOCKSTATES);
         options.put("chunk-processor.max-entities", Settings.CHUNK_PROCESSOR_MAX_ENTITIES);
         options.put("chunk-processor.disable-physics", Settings.CHUNK_PROCESSOR_DISABLE_PHYSICS);
@@ -1951,6 +1953,10 @@ public class PS {
         
         // Chunk processor
         Settings.CHUNK_PROCESSOR = config.getBoolean("chunk-processor.enabled");
+        
+        Settings.CHUNK_PROCESSOR_GC = config.getBoolean("chunk-processor.auto-unload");
+        Settings.CHUNK_PROCESSOR_TRIM_ON_SAVE = config.getBoolean("chunk-processor.auto-trim");
+        
         Settings.CHUNK_PROCESSOR_MAX_BLOCKSTATES = config.getInt("chunk-processor.max-blockstates");
         Settings.CHUNK_PROCESSOR_MAX_ENTITIES = config.getInt("chunk-processor.max-entities");
         Settings.CHUNK_PROCESSOR_DISABLE_PHYSICS = config.getBoolean("chunk-processor.disable-physics");

src/main/java/com/intellectualcrafters/plot/config/Settings.java

@@ -68,6 +68,8 @@ public class Settings {
      * Chunk processor
      */
     public static boolean CHUNK_PROCESSOR = false;
+    public static boolean CHUNK_PROCESSOR_TRIM_ON_SAVE = false;
+    public static boolean CHUNK_PROCESSOR_GC = false;
     public static int CHUNK_PROCESSOR_MAX_BLOCKSTATES = 4096;
     public static int CHUNK_PROCESSOR_MAX_ENTITIES = 512;
     public static boolean CHUNK_PROCESSOR_DISABLE_PHYSICS = false;

src/main/java/com/plotsquared/bukkit/listeners/ChunkListener.java

@@ -1,10 +1,16 @@
 package com.plotsquared.bukkit.listeners;
 
+import static com.intellectualcrafters.plot.util.ReflectionUtils.getRefClass;
+
+import java.util.HashMap;
+import java.util.Map.Entry;
+
 import org.bukkit.Bukkit;
 import org.bukkit.Chunk;
 import org.bukkit.Material;
 import org.bukkit.World;
 import org.bukkit.block.BlockState;
+import org.bukkit.craftbukkit.v1_8_R2.CraftChunk;
 import org.bukkit.entity.Entity;
 import org.bukkit.entity.Item;
 import org.bukkit.entity.LivingEntity;
@@ -17,21 +23,143 @@ import org.bukkit.event.entity.CreatureSpawnEvent;
 import org.bukkit.event.entity.ItemSpawnEvent;
 import org.bukkit.event.world.ChunkLoadEvent;
 import org.bukkit.event.world.ChunkUnloadEvent;
+import org.bukkit.event.world.WorldSaveEvent;
 
 import com.intellectualcrafters.plot.PS;
 import com.intellectualcrafters.plot.config.Settings;
-import com.intellectualcrafters.plot.object.PseudoRandom;
-import com.intellectualcrafters.plot.util.ChunkManager;
+import com.intellectualcrafters.plot.object.ChunkLoc;
+import com.intellectualcrafters.plot.object.Location;
+import com.intellectualcrafters.plot.object.Plot;
+import com.intellectualcrafters.plot.object.PlotPlayer;
+import com.intellectualcrafters.plot.util.MainUtil;
+import com.intellectualcrafters.plot.util.ReflectionUtils.RefClass;
+import com.intellectualcrafters.plot.util.ReflectionUtils.RefField;
+import com.intellectualcrafters.plot.util.ReflectionUtils.RefMethod;
 import com.intellectualcrafters.plot.util.TaskManager;
+import com.intellectualcrafters.plot.util.UUIDHandler;
 
 public class ChunkListener implements Listener {
 
     private Chunk lastChunk = null;
-    private long last = 0;
-    private int count = 0;
+    
+    final RefClass classChunk = getRefClass("{nms}.Chunk");
+    final RefClass classCraftChunk = getRefClass("{cb}.CraftChunk");
+    final RefMethod methodGetHandleChunk;
+    final RefField mustSave = classChunk.getField("mustSave");
+    
+    public ChunkListener() {
+        RefMethod method;
+        try {
+            method = classCraftChunk.getMethod("getHandle");
+        }
+        catch (Exception e) {
+            method = null;
+            e.printStackTrace();
+        }
+        methodGetHandleChunk = method;
+        
+        if (!Settings.CHUNK_PROCESSOR_GC) {
+            return;
+        }
+        TaskManager.runTaskRepeat(new Runnable() {
+            @Override
+            public void run() {
+                int distance = Bukkit.getViewDistance() + 1;
+                HashMap<String, HashMap<ChunkLoc, Integer>> players = new HashMap<>();
+                for (Entry<String, PlotPlayer> entry : UUIDHandler.getPlayers().entrySet()) {
+                    PlotPlayer pp = entry.getValue();
+                    Location loc = pp.getLocation();
+                    String world = loc.getWorld();
+                    HashMap<ChunkLoc, Integer> map = players.get(world);
+                    if (map == null) {
+                        map = new HashMap<>();
+                        players.put(world, map);
+                    }
+                    ChunkLoc origin = new ChunkLoc(loc.getX() >> 4, loc.getZ() >> 4);
+                    Integer val = map.get(origin);
+                    int check;
+                    if (val != null) {
+                        if (val == distance) {
+                            continue;
+                        }
+                        check = distance - val;
+                    }
+                    else {
+                        check = distance;
+                        map.put(origin, distance);
+                    }
+                    for (int x = -distance; x <= distance; x++) {
+                        if (x >= check || -x >= check) {
+                            continue;
+                        }
+                        for (int z = -distance; z <= distance; z++) {
+                            if (z >= check || -z >= check) {
+                                continue;
+                            }
+                            int weight = distance - Math.max(Math.abs(x), Math.abs(z));
+                            ChunkLoc chunk = new ChunkLoc(x + origin.x, z + origin.z);
+                            val = map.get(chunk);
+                            if (val == null || val < weight) {
+                                map.put(chunk, weight);
+                            }
+                            
+                        }
+                    }
+                }
+                for (World world : Bukkit.getWorlds()) {
+                    String name = world.getName();
+                    boolean autosave = world.isAutoSave();
+                    boolean plotworld = PS.get().isPlotWorld(name);
+                    if (autosave && plotworld) {
+                        world.setAutoSave(false);
+                    }
+                    HashMap<ChunkLoc, Integer> map = players.get(name);
+                    if (map == null || map.size() == 0) {
+                        continue;
+                    }
+                    for (Chunk chunk : world.getLoadedChunks()) {
+                        int x = chunk.getX();
+                        int z = chunk.getZ();
+                        if (!map.containsKey(new ChunkLoc(x, z))) {
+                            Plot plot = MainUtil.getPlot(new Location(name, x << 4, 1, z << 4));
+                            if (Settings.CHUNK_PROCESSOR_TRIM_ON_SAVE && plot == null || plot.owner == null && plotworld) {
+                                unloadChunk(chunk);
+                                CraftChunk c = null;
+                            }
+                            else {
+                                chunk.unload(true, false);
+                            }
+                        }
+                    }
+                    if (!Settings.CHUNK_PROCESSOR_TRIM_ON_SAVE && autosave && plotworld) {
+                        world.setAutoSave(true);
+                    }
+                }
+            }
+        }, 300);
+    }
+    
+    public void unloadChunk(Chunk chunk) {
+        Object c = methodGetHandleChunk.of(chunk).call();
+        mustSave.of(c).set(false);
+        chunk.unload(false, false);
+    }
     
     @EventHandler
     public void onChunkUnload(ChunkUnloadEvent event) {
+        if (Settings.CHUNK_PROCESSOR_TRIM_ON_SAVE) {
+            Chunk chunk = event.getChunk();
+            String world = chunk.getWorld().getName();
+            if (PS.get().isPlotWorld(world)) {
+                int x = chunk.getX();
+                int z = chunk.getZ();
+                Plot plot = MainUtil.getPlot(new Location(world, x << 4, 1, z << 4));
+                if (plot == null || plot.owner == null && PS.get().isPlotWorld(world)) {
+                    unloadChunk(chunk);
+                    return;
+                }
+            }
+        }
         if (processChunk(event.getChunk(), true)) {
             event.setCancelled(true);
         }