Add render statistics, support for tile hashcodes to stop non-updates

configuration.txt

@@ -65,6 +65,9 @@ display-whitelist: false
 # How often a tile gets rendered (in seconds).
 renderinterval: 1
 
+# Tile hashing is used to minimize tile file updates when no changes have occurred - set to false to disable
+enabletilehash: true
+
 render-triggers:
 #  - chunkloaded
 #  - playermove

src/main/java/org/dynmap/DynmapPlugin.java

@@ -277,7 +277,9 @@ public class DynmapPlugin extends JavaPlugin {
         "hide",
         "show",
         "fullrender",
-        "reload" }));
+        "reload",
+        "stats",
+        "resetstats" }));
 
     @Override
     public boolean onCommand(CommandSender sender, Command cmd, String commandLabel, String[] args) {
@@ -343,6 +345,16 @@ public class DynmapPlugin extends JavaPlugin {
                 sender.sendMessage("Reloading Dynmap...");
                 reload();
                 sender.sendMessage("Dynmap reloaded");
+            } else if (c.equals("stats") && checkPlayerPermission(sender, "stats")) {
+                if(args.length == 1)
+                    mapManager.printStats(sender, null);
+                else
+                    mapManager.printStats(sender, args[1]);
+            } else if (c.equals("resetstats") && checkPlayerPermission(sender, "resetstats")) {
+                if(args.length == 1)
+                    mapManager.resetStats(sender, null);
+                else
+                    mapManager.resetStats(sender, args[1]);
             }
             return true;
         }

src/main/java/org/dynmap/MapManager.java

@@ -8,6 +8,7 @@ import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.TreeSet;
 import java.util.concurrent.ScheduledThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.Callable;
@@ -15,6 +16,7 @@ import java.util.concurrent.Future;
 import org.bukkit.Location;
 import org.bukkit.World;
 import org.bukkit.scheduler.BukkitScheduler;
+import org.bukkit.command.CommandSender;
 import org.dynmap.debug.Debug;
 
 public class MapManager {
@@ -27,16 +29,26 @@ public class MapManager {
     private long timeslice_int = 0; /* In milliseconds */
     /* Which fullrenders are active */
     private HashMap<String, FullWorldRenderState> active_renders = new HashMap<String, FullWorldRenderState>();
-
+    /* Tile hash manager */
+    public TileHashManager hashman;
     /* lock for our data structures */
     public static final Object lock = new Object();
 
     public static MapManager mapman;    /* Our singleton */
 
     /* Thread pool for processing renders */
-    private ScheduledThreadPoolExecutor renderpool;
+    private DynmapScheduledThreadPoolExecutor renderpool;
     private static final int POOL_SIZE = 3;    
 
+    private HashMap<String, MapStats> mapstats = new HashMap<String, MapStats>();
+    
+    private static class MapStats {
+        int loggedcnt;
+        int renderedcnt;
+        int updatedcnt;
+        int transparentcnt;
+    }
+
     public DynmapWorld getWorld(String name) {
         DynmapWorld world = worldsLookup.get(name);
         return world;
@@ -46,6 +58,21 @@ public class MapManager {
         return worlds;
     }
     
+    private class DynmapScheduledThreadPoolExecutor extends ScheduledThreadPoolExecutor {
+        DynmapScheduledThreadPoolExecutor() {
+            super(POOL_SIZE);
+        }
+
+        protected void afterExecute(Runnable r, Throwable x) {
+            if(r instanceof FullWorldRenderState) {
+                ((FullWorldRenderState)r).cleanup();
+            }
+            if(x != null) {
+                Log.severe("Exception during render job: " + r);
+                x.printStackTrace();
+            }
+        }
+    }
     /* This always runs on render pool threads - no bukkit calls from here */ 
     private class FullWorldRenderState implements Runnable {
         DynmapWorld world;    /* Which world are we rendering */
@@ -56,6 +83,7 @@ public class MapManager {
         HashSet<MapTile> rendered = null;
         LinkedList<MapTile> renderQueue = null;
         MapTile tile0 = null;
+        MapTile tile = null;
         int rendercnt = 0;
 
         /* Full world, all maps render */
@@ -73,8 +101,18 @@ public class MapManager {
             tile0 = t;
         }
 
+        public String toString() {
+            return "world=" + world.world.getName() + ", map=" + map + " tile=" + tile;
+        }
+        
+        public void cleanup() {
+            if(tile0 == null) {
+                synchronized(lock) {
+                    active_renders.remove(world.world.getName());
+                }
+            }
+        }
         public void run() {
-            MapTile tile;
             long tstart = System.currentTimeMillis();
             
             if(tile0 == null) {    /* Not single tile render */
@@ -90,9 +128,7 @@ public class MapManager {
                     map_index++;    /* Next map */
                     if(map_index >= world.maps.size()) {    /* Last one done? */
                         Log.info("Full render of '" + world.world.getName() + "' finished.");
-                        synchronized(lock) {
-                            active_renders.remove(world.world.getName());
-                        }
+                        cleanup();
                         return;
                     }
                     map = world.maps.get(map_index);
@@ -125,6 +161,7 @@ public class MapManager {
             DynmapChunk[] requiredChunks = tile.getMap().getRequiredChunks(tile);
             MapChunkCache cache = createMapChunkCache(w, requiredChunks);
             if(cache == null) {
+                cleanup();
                 return; /* Cancelled/aborted */
             }
             if(tile0 != null) {    /* Single tile? */
@@ -159,6 +196,9 @@ public class MapManager {
                     renderpool.execute(this);
                 }
             }
+            else {
+                cleanup();
+            }
         }
     }
 
@@ -193,6 +233,8 @@ public class MapManager {
 
         scheduler = plugin.getServer().getScheduler();
 
+        hashman = new TileHashManager(DynmapPlugin.tilesDirectory, configuration.getBoolean("enabletilehash", true));
+        
         tileQueue.start();
         
         for (World world : plug_in.getServer().getWorlds()) {
@@ -308,7 +350,7 @@ public class MapManager {
 
     public void startRendering() {
         tileQueue.start();
-        renderpool = new ScheduledThreadPoolExecutor(POOL_SIZE);
+        renderpool = new DynmapScheduledThreadPoolExecutor();
     }
 
     public void stopRendering() {
@@ -379,4 +421,65 @@ public class MapManager {
             return null;
         }
     }
+    /**
+     *  Update map tile statistics
+     */
+    public void updateStatistics(MapTile tile, String subtype, boolean rendered, boolean updated, boolean transparent) {
+        synchronized(lock) {
+            String k = tile.getKey();
+            if(subtype != null)
+                k += "." + subtype;
+            MapStats ms = mapstats.get(k);
+            if(ms == null) {
+                ms = new MapStats();
+                mapstats.put(k, ms);
+            }
+            ms.loggedcnt++;
+            if(rendered)
+                ms.renderedcnt++;
+            if(updated)
+                ms.updatedcnt++;
+            if(transparent)
+                ms.transparentcnt++;
+        }
+    }
+    /**
+     * Print statistics command
+     */
+    public void printStats(CommandSender sender, String prefix) {
+        sender.sendMessage("Tile Render Statistics:");
+        MapStats tot = new MapStats();
+        synchronized(lock) {
+            for(String k: new TreeSet<String>(mapstats.keySet())) {
+                if((prefix != null) && !k.startsWith(prefix))
+                    continue;
+                MapStats ms = mapstats.get(k);
+                sender.sendMessage("  " + k + ": processed=" + ms.loggedcnt + ", rendered=" + ms.renderedcnt + 
+                               ", updated=" + ms.updatedcnt + ", transparent=" + ms.transparentcnt);
+                tot.loggedcnt += ms.loggedcnt;
+                tot.renderedcnt += ms.renderedcnt;
+                tot.updatedcnt += ms.updatedcnt;
+                tot.transparentcnt += ms.transparentcnt;
+            }
+        }
+        sender.sendMessage("  TOTALS: processed=" + tot.loggedcnt + ", rendered=" + tot.renderedcnt + 
+                           ", updated=" + tot.updatedcnt + ", transparent=" + tot.transparentcnt);
+    }
+    /**
+     * Reset statistics
+     */
+    public void resetStats(CommandSender sender, String prefix) {
+        synchronized(lock) {
+            for(String k : mapstats.keySet()) {
+                if((prefix != null) && !k.startsWith(prefix))
+                    continue;
+                MapStats ms = mapstats.get(k);
+                ms.loggedcnt = 0;
+                ms.renderedcnt = 0;
+                ms.updatedcnt = 0;
+                ms.transparentcnt = 0;
+            }
+        }
+        sender.sendMessage("Tile Render Statistics reset");
+    }
 }

src/main/java/org/dynmap/MapTile.java

@@ -36,4 +36,8 @@ public abstract class MapTile {
         }
         return super.equals(obj);
     }
+    
+    public String getKey() {
+        return world.getName() + "." + map.getName();
+    }
 }

src/main/java/org/dynmap/MapType.java

@@ -18,4 +18,6 @@ public abstract class MapType {
     
     public void buildClientConfiguration(JSONObject worldObject) {
     }
+    
+    public abstract String getName();
 }

src/main/java/org/dynmap/TileHashManager.java

@@ -0,0 +1,152 @@
+package org.dynmap;
+import java.io.File;
+import java.io.RandomAccessFile;
+import java.util.Arrays;
+import java.util.LinkedHashMap;
+import java.io.IOException;
+import java.util.zip.CRC32;
+
+/**
+ * Image hash code manager - used to reduce compression and notification of updated tiles that do not actually yield new content
+ *
+ */
+public class TileHashManager {
+    private File    tiledir;    /* Base tile directory */    
+    private boolean enabled;
+    
+    /**
+     * Each tile hash file is a 32x32 tile grid, with each file having a CRC32 hash code generated from its pre-compression frame buffer
+     */
+    private static class TileHashFile {
+        final String key;
+        final String subtype;
+        final int x;  /* minimum tile coordinate / 32 */
+        final int y;  /* minimum tile coordinate / 32 */
+        private File hf;
+        TileHashFile(String key, String subtype, int x, int y) {
+            this.key = key;
+            if(subtype != null)
+                this.subtype = subtype;
+            else
+                this.subtype = "";
+            this.x = x;
+            this.y = y;
+        }
+        @Override
+        public boolean equals(Object o) {
+            if(!(o instanceof TileHashFile))
+                return false;
+            TileHashFile fo = (TileHashFile)o;
+            return (x == fo.x) && (y == fo.y) && key.equals(fo.key) && (subtype.equals(fo.subtype)); 
+        }
+        @Override
+        public int hashCode() {
+            return key.hashCode() ^ subtype.hashCode() ^ (x << 16) ^ y;
+        }
+        
+        public File getHashFile(File tiledir) {
+            if(hf == null)
+                hf = new File(tiledir, key + (subtype.equals("")?"":("." + subtype)) + "_" + x + "_" + y + ".hash");
+            return hf;
+        }
+        /* Write to file */
+        public void writeToFile(File tiledir, byte[] crcbuf) {
+            try {
+                RandomAccessFile fd = new RandomAccessFile(getHashFile(tiledir), "rw");
+                fd.seek(0);
+                fd.write(crcbuf);
+                fd.close();
+            } catch (IOException iox) {
+                Log.severe("Error writing hash file - " + getHashFile(tiledir).getPath());
+            }
+        }
+        
+        /* Read from file */
+        public void readFromFile(File tiledir, byte[] crcbuf) {
+            try {
+                RandomAccessFile fd = new RandomAccessFile(getHashFile(tiledir), "r");
+                fd.seek(0);
+                fd.read(crcbuf);
+                fd.close();
+            } catch (IOException iox) {
+                Arrays.fill(crcbuf, (byte)0xFF);
+                writeToFile(tiledir, crcbuf);
+            }
+        }
+        /* Read CRC */
+        public long getCRC(int tx, int ty, byte[] crcbuf) {
+            int off = (128 * (ty & 0x1F)) + (4 * (tx & 0x1F));
+            long crc = 0;
+            for(int i = 0; i < 4; i++)
+                crc = (crc << 8) + (0xFF & (int)crcbuf[off+i]);
+            return crc;
+        }
+        /* Set CRC */
+        public void setCRC(int tx, int ty, byte[] crcbuf, long crc) {
+            int off = (128 * (ty & 0x1F)) + (4 * (tx & 0x1F));
+            for(int i = 0; i < 4; i++)
+                crcbuf[off+i] = (byte)((crc >> ((3-i)*8)) & 0xFF);
+        }
+    }
+    private Object lock = new Object();
+    private LinkedHashMap<TileHashFile, byte[]> tilehash = new LinkedHashMap<TileHashFile, byte[]>(16, (float) 0.75, true);
+    private CRC32 crc32 = new CRC32();
+    
+    public TileHashManager(File tileroot, boolean enabled) {
+        tiledir = tileroot;
+        this.enabled = enabled;
+    }
+    
+    /* Read cached hashcode for given tile */
+    public long getImageHashCode(String key, String subtype, int tx, int ty) {
+        if(!enabled) {
+            return -1;  /* Return value that never matches */
+        }
+        TileHashFile thf = new TileHashFile(key, subtype, tx >> 5, ty >> 5);
+        synchronized(lock) {
+            byte[] crcbuf = tilehash.get(thf);  /* See if we have it cached */
+            if(crcbuf == null) {    /* If not in cache, load it */
+                crcbuf = new byte[32*32*4]; /* Get our space */
+                Arrays.fill(crcbuf, (byte)0xFF);    /* Fill with -1 */
+                tilehash.put(thf, crcbuf);  /* Add to cache */
+                thf.readFromFile(tiledir, crcbuf);
+            }
+            return thf.getCRC(tx & 0x1F, ty & 0x1F, crcbuf);
+        }
+    }
+    /* Calculate hash code for given buffer */
+    public long calculateTileHash(int[] newbuf) {
+        if(!enabled) {
+            return 0;   /* Return value that doesn't match */
+        }
+        synchronized(lock) {
+            /* Calculate CRC-32 for buffer */
+            crc32.reset();
+            for(int i = 0; i < newbuf.length; i++) {
+                int v = newbuf[i];
+                crc32.update(0xFF & v);
+                crc32.update(0xFF & (v >> 8));
+                crc32.update(0xFF & (v >> 16));
+                crc32.update(0xFF & (v >> 24));
+            }
+            return crc32.getValue();
+        }
+    }
+    /* Update hashcode for given tile */
+    public void updateHashCode(String key, String subtype, int tx, int ty, long newcrc) {
+        if(!enabled)
+            return;
+        synchronized(lock) {
+            /* Now, find and check existing value */
+            TileHashFile thf = new TileHashFile(key, subtype, tx >> 5, ty >> 5);
+            byte[] crcbuf = tilehash.get(thf);  /* See if we have it cached */
+            if(crcbuf == null) {    /* If not in cache, load it */
+                crcbuf = new byte[32*32*4]; /* Get our space */
+                tilehash.put(thf, crcbuf);  /* Add to cache */
+                thf.readFromFile(tiledir, crcbuf);
+            }
+            thf.setCRC(tx & 0x1F, ty & 0x1F, crcbuf, newcrc);   /* Update field */
+            thf.writeToFile(tiledir, crcbuf);   /* And write it out */
+        }
+    }    
+}

src/main/java/org/dynmap/flat/FlatMap.java

@@ -20,6 +20,7 @@ import org.dynmap.ColorScheme;
 import org.dynmap.ConfigurationNode;
 import org.dynmap.DynmapChunk;
 import org.dynmap.MapManager;
+import org.dynmap.TileHashManager;
 import org.dynmap.MapTile;
 import org.dynmap.MapType;
 import org.dynmap.debug.Debug;
@@ -234,35 +235,63 @@ public class FlatMap extends MapType {
                 rendered = true;
             }
         }
-        /* Wrap buffer as buffered image */
-        Debug.debug("saving image " + outputFile.getPath());
-        try {
-            ImageIO.write(im.buf_img, "png", outputFile);
-        } catch (IOException e) {
-            Debug.error("Failed to save image: " + outputFile.getPath(), e);
-        } catch (java.lang.NullPointerException e) {
-            Debug.error("Failed to save image (NullPointerException): " + outputFile.getPath(), e);
+        /* Test to see if we're unchanged from older tile */
+        TileHashManager hashman = MapManager.mapman.hashman;
+        long crc = hashman.calculateTileHash(argb_buf);
+        boolean tile_update = false;
+        if((!outputFile.exists()) || (crc != hashman.getImageHashCode(tile.getKey(), null, t.x, t.y))) {
+            /* Wrap buffer as buffered image */
+            Debug.debug("saving image " + outputFile.getPath());
+            try {
+                ImageIO.write(im.buf_img, "png", outputFile);
+            } catch (IOException e) {
+                Debug.error("Failed to save image: " + outputFile.getPath(), e);
+            } catch (java.lang.NullPointerException e) {
+                Debug.error("Failed to save image (NullPointerException): " + outputFile.getPath(), e);
+            }
+            MapManager.mapman.pushUpdate(tile.getWorld(), new Client.Tile(tile.getFilename()));
+            hashman.updateHashCode(tile.getKey(), null, t.x, t.y, crc);
+            tile_update = true;
+        }
+        else {
+            Debug.debug("skipping image " + outputFile.getPath() + " - hash match");
         }
         KzedMap.freeBufferedImage(im);
-        MapManager.mapman.pushUpdate(tile.getWorld(), new Client.Tile(tile.getFilename()));
+        MapManager.mapman.updateStatistics(tile, null, true, tile_update, !rendered);
 
         /* If day too, handle it */
         if(night_and_day) {
             File dayfile = new File(outputFile.getParent(), tile.getDayFilename());
-            Debug.debug("saving image " + dayfile.getPath());
-            try {
-                ImageIO.write(im_day.buf_img, "png", dayfile);
-            } catch (IOException e) {
-                Debug.error("Failed to save image: " + dayfile.getPath(), e);
-            } catch (java.lang.NullPointerException e) {
-                Debug.error("Failed to save image (NullPointerException): " + dayfile.getPath(), e);
+
+            crc = hashman.calculateTileHash(argb_buf_day);
+            if((!dayfile.exists()) || (crc != hashman.getImageHashCode(tile.getKey(), "day", t.x, t.y))) {
+                Debug.debug("saving image " + dayfile.getPath());
+                try {
+                    ImageIO.write(im_day.buf_img, "png", dayfile);
+                } catch (IOException e) {
+                    Debug.error("Failed to save image: " + dayfile.getPath(), e);
+                } catch (java.lang.NullPointerException e) {
+                    Debug.error("Failed to save image (NullPointerException): " + dayfile.getPath(), e);
+                }
+                MapManager.mapman.pushUpdate(tile.getWorld(), new Client.Tile(tile.getDayFilename()));   
+                hashman.updateHashCode(tile.getKey(), "day", t.x, t.y, crc);
+                tile_update = true;
+            }
+            else {
+                Debug.debug("skipping image " + dayfile.getPath() + " - hash match");
+                tile_update = false;
             }
             KzedMap.freeBufferedImage(im_day);
-            MapManager.mapman.pushUpdate(tile.getWorld(), new Client.Tile(tile.getDayFilename()));   
+            MapManager.mapman.updateStatistics(tile, "day", true, tile_update, !rendered);
         }
         
         return rendered;
     }
+    
+    public String getName() {
+        return prefix;
+    }
+
 
     public static class FlatMapTile extends MapTile {
         FlatMap map;
@@ -286,6 +315,9 @@ public class FlatMap extends MapType {
         public String getDayFilename() {
             return map.prefix + "_day_" + size + "_" + -(y+1) + "_" + x + ".png";
         }
+        public String toString() {
+            return getWorld().getName() + ":" + getFilename();
+        }
     }
     
     @Override

src/main/java/org/dynmap/kzedmap/DefaultTileRenderer.java

@@ -16,6 +16,7 @@ import org.dynmap.Color;
 import org.dynmap.ColorScheme;
 import org.dynmap.ConfigurationNode;
 import org.dynmap.MapManager;
+import org.dynmap.TileHashManager;
 import org.dynmap.debug.Debug;
 import org.dynmap.MapChunkCache;
 import org.dynmap.kzedmap.KzedMap.KzedBufferedImage;
@@ -188,7 +189,7 @@ public class DefaultTileRenderer implements MapTileRenderer {
                 (KzedMap) tile.getMap(), tile);
         File zoomFile = MapManager.mapman.getTileFile(zmtile);
 
-        doFileWrites(outputFile, tile, im, im_day, zmtile, zoomFile, zim, zim_day);
+        doFileWrites(outputFile, tile, im, im_day, zmtile, zoomFile, zim, zim_day, !isempty);
 
         return !isempty;
     }
@@ -220,49 +221,83 @@ public class DefaultTileRenderer implements MapTileRenderer {
     private void doFileWrites(final File fname, final KzedMapTile mtile,
         final KzedBufferedImage img, final KzedBufferedImage img_day, 
         final KzedZoomedMapTile zmtile, final File zoomFile,
-        final KzedBufferedImage zimg, final KzedBufferedImage zimg_day) {
-        Debug.debug("saving image " + fname.getPath());
-        try {
-            ImageIO.write(img.buf_img, "png", fname);
-        } catch (IOException e) {
-            Debug.error("Failed to save image: " + fname.getPath(), e);
-        } catch (java.lang.NullPointerException e) {
-            Debug.error("Failed to save image (NullPointerException): " + fname.getPath(), e);
+        final KzedBufferedImage zimg, final KzedBufferedImage zimg_day, boolean rendered) {
+
+        /* Get coordinates of zoomed tile */
+        int ox = (mtile.px == zmtile.getTileX())?0:KzedMap.tileWidth/2;
+        int oy = (mtile.py == zmtile.getTileY())?0:KzedMap.tileHeight/2;
+
+        /* Test to see if we're unchanged from older tile */
+        TileHashManager hashman = MapManager.mapman.hashman;
+        long crc = hashman.calculateTileHash(img.argb_buf);
+        boolean updated_fname = false;
+        if((!fname.exists()) || (crc != hashman.getImageHashCode(mtile.getKey(), null, mtile.px, mtile.py))) {
+            Debug.debug("saving image " + fname.getPath());
+            try {
+                ImageIO.write(img.buf_img, "png", fname);
+            } catch (IOException e) {
+                Debug.error("Failed to save image: " + fname.getPath(), e);
+            } catch (java.lang.NullPointerException e) {
+                Debug.error("Failed to save image (NullPointerException): " + fname.getPath(), e);
+            }
+            MapManager.mapman.pushUpdate(mtile.getWorld(), new Client.Tile(mtile.getFilename()));
+            hashman.updateHashCode(mtile.getKey(), null, mtile.px, mtile.py, crc);
+            updated_fname = true;
         }
         KzedMap.freeBufferedImage(img);
+        MapManager.mapman.updateStatistics(mtile, null, true, updated_fname, !rendered);
+
+        mtile.file = fname;
+
+        boolean updated_dfname = false;
+        File dfname = new File(fname.getParent(), mtile.getDayFilename());
         if(img_day != null) {
-            File dfname = new File(fname.getParent(), mtile.getDayFilename());
-            Debug.debug("saving image " + dfname.getPath());
-            try {
-                ImageIO.write(img_day.buf_img, "png", dfname);
-            } catch (IOException e) {
-                Debug.error("Failed to save image: " + dfname.getPath(), e);
-            } catch (java.lang.NullPointerException e) {
-                Debug.error("Failed to save image (NullPointerException): " + dfname.getPath(), e);
+            crc = hashman.calculateTileHash(img.argb_buf);
+            if((!dfname.exists()) || (crc != hashman.getImageHashCode(mtile.getKey(), "day", mtile.px, mtile.py))) {
+                Debug.debug("saving image " + dfname.getPath());
+                try {
+                    ImageIO.write(img_day.buf_img, "png", dfname);
+                } catch (IOException e) {
+                    Debug.error("Failed to save image: " + dfname.getPath(), e);
+                } catch (java.lang.NullPointerException e) {
+                    Debug.error("Failed to save image (NullPointerException): " + dfname.getPath(), e);
+                }
+                MapManager.mapman.pushUpdate(mtile.getWorld(), new Client.Tile(mtile.getDayFilename()));
+                hashman.updateHashCode(mtile.getKey(), "day", mtile.px, mtile.py, crc);
+                updated_dfname = true;
             }
             KzedMap.freeBufferedImage(img_day);
+            MapManager.mapman.updateStatistics(mtile, "day", true, updated_dfname, !rendered);
         }
-        mtile.file = fname;
+        
         // Since we've already got the new tile, and we're on an async thread, just
         // make the zoomed tile here
-        int px = mtile.px;
-        int py = mtile.py;
-        int zpx = zmtile.getTileX();
-        int zpy = zmtile.getTileY();
-
-        /* scaled size */
-        int scw = KzedMap.tileWidth / 2;
-        int sch = KzedMap.tileHeight / 2;
-
-        /* origin in zoomed-out tile */
-        int ox = 0;
-        int oy = 0;
-
-        if (zpx != px)
-            ox = scw;
-        if (zpy != py)
-            oy = sch;
+        boolean ztile_updated = false;
+        if(updated_fname || (!zoomFile.exists())) {
+            saveZoomedTile(zmtile, zoomFile, zimg, ox, oy);
+            MapManager.mapman.pushUpdate(zmtile.getWorld(),
+                                         new Client.Tile(zmtile.getFilename()));
+            ztile_updated = true;
+        }
+        KzedMap.freeBufferedImage(zimg);
+        MapManager.mapman.updateStatistics(zmtile, null, true, ztile_updated, !rendered);
+        
+        if(zimg_day != null) {
+            File zoomFile_day = new File(zoomFile.getParent(), zmtile.getDayFilename());
+            ztile_updated = false;
+            if(updated_dfname || (!zoomFile_day.exists())) {
+                saveZoomedTile(zmtile, zoomFile_day, zimg_day, ox, oy);
+                MapManager.mapman.pushUpdate(zmtile.getWorld(),
+                                             new Client.Tile(zmtile.getDayFilename()));            
+                ztile_updated = true;
+            }
+            KzedMap.freeBufferedImage(zimg_day);
+            MapManager.mapman.updateStatistics(zmtile, "day", true, ztile_updated, !rendered);
+        }
+    }
 
+    private void saveZoomedTile(final KzedZoomedMapTile zmtile, final File zoomFile,
+            final KzedBufferedImage zimg, int ox, int oy) {
         BufferedImage zIm = null;
         KzedBufferedImage kzIm = null;
         try {
@@ -284,7 +319,6 @@ public class DefaultTileRenderer implements MapTileRenderer {
 
         /* blit scaled rendered tile onto zoom-out tile */
         zIm.setRGB(ox, oy, KzedMap.tileWidth/2, KzedMap.tileHeight/2, zimg.argb_buf, 0, KzedMap.tileWidth/2);
-        KzedMap.freeBufferedImage(zimg);
 
         /* save zoom-out tile */
 
@@ -300,61 +334,8 @@ public class DefaultTileRenderer implements MapTileRenderer {
             KzedMap.freeBufferedImage(kzIm);
         else
             zIm.flush();
-        
-        if(zimg_day != null) {
-            File zoomFile_day = new File(zoomFile.getParent(), zmtile.getDayFilename());
-            
-            zIm = null;
-            kzIm = null;
-            try {
-                zIm = ImageIO.read(zoomFile_day);
-            } catch (IOException e) {
-            } catch (IndexOutOfBoundsException e) {
-            }
 
-            zIm_allocated = false;
-            if (zIm == null) {
-                /* create new one */
-                kzIm = KzedMap.allocateBufferedImage(KzedMap.tileWidth, KzedMap.tileHeight);
-                zIm = kzIm.buf_img;
-                zIm_allocated = true;
-                Debug.debug("New zoom-out tile created " + zmtile.getFilename());
-            } else {
-                Debug.debug("Loaded zoom-out tile from " + zmtile.getFilename());
-            }
-
-            /* blit scaled rendered tile onto zoom-out tile */
-            zIm.setRGB(ox, oy, KzedMap.tileWidth/2, KzedMap.tileHeight/2, zimg_day.argb_buf, 0, KzedMap.tileWidth/2);
-            KzedMap.freeBufferedImage(zimg_day);
-
-            /* save zoom-out tile */
-
-            try {
-                ImageIO.write(zIm, "png", zoomFile_day);
-                Debug.debug("Saved zoom-out tile at " + zoomFile_day.getName());
-            } catch (IOException e) {
-                Debug.error("Failed to save zoom-out tile: " + zoomFile_day.getName(), e);
-            } catch (java.lang.NullPointerException e) {
-                Debug.error("Failed to save zoom-out tile (NullPointerException): " + zoomFile_day.getName(), e);
-            }
-            if(zIm_allocated)
-                KzedMap.freeBufferedImage(kzIm);
-            else
-                zIm.flush();
-        }
-        /* Push updates for both files.*/
-        MapManager.mapman.pushUpdate(mtile.getWorld(),
-            new Client.Tile(mtile.getFilename()));
-        MapManager.mapman.pushUpdate(zmtile.getWorld(),
-                new Client.Tile(zmtile.getFilename()));
-        if(img_day != null) {
-            MapManager.mapman.pushUpdate(mtile.getWorld(),
-                                         new Client.Tile(mtile.getDayFilename()));
-            MapManager.mapman.pushUpdate(zmtile.getWorld(),
-                                         new Client.Tile(zmtile.getDayFilename()));            
-        }
     }
-
     protected void scan(World world, int seq, boolean isnether, final Color result, final Color result_day,
             MapChunkCache.MapIterator mapiter) {
         int lightlevel = 15;

src/main/java/org/dynmap/kzedmap/KzedMap.java

@@ -317,7 +317,11 @@ public class KzedMap extends MapType {
             }
         }
     }    
-    
+
+    public String getName() {
+        return "KzedMap";
+    }
+
     @Override
     public void buildClientConfiguration(JSONObject worldObject) {
         for(MapTileRenderer renderer : renderers) {

src/main/java/org/dynmap/kzedmap/KzedMapTile.java

@@ -48,6 +48,10 @@ public class KzedMapTile extends MapTile {
         return o.px == px && o.py == py && o.getWorld().equals(getWorld());
     }
 
+    public String getKey() {
+        return getWorld().getName() + "." + renderer.getName();
+    }
+
     public String toString() {
         return getWorld().getName() + ":" + getFilename();
     }

src/main/java/org/dynmap/kzedmap/KzedZoomedMapTile.java

@@ -56,4 +56,10 @@ public class KzedZoomedMapTile extends MapTile {
         }
         return super.equals(obj);
     }
+    
+
+    public String getKey() {
+        return getWorld().getName() + ".z" + originalTile.renderer.getName();
+    }
+
 }