git.gag.com Git - fw/altos/blob - altoslib/AltosMapCache.java

   1 /*
   2  * Copyright © 2010 Anthony Towns <aj@erisian.com.au>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; version 2 of the License.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  16  */
  17
  18 package org.altusmetrum.altoslib_9;
  19
  20 import java.io.*;
  21 import java.net.*;
  22
  23 public class AltosMapCache implements AltosMapCacheListener {
  24
  25         /* An entry in the MapCache */
  26         class MapCacheElement implements AltosMapStoreListener {
  27
  28                 AltosMapTile            tile;           /* Notify when image has been loaded */
  29                 AltosImage              image;
  30                 AltosMapStore           store;
  31                 long                    used;
  32
  33                 class loader implements Runnable {
  34                         public void run() {
  35                                 if (image != null)
  36                                         tile.notify_image(image);
  37                                 try {
  38                                         image = map_interface.load_image(store.file);
  39                                 } catch (Exception ex) {
  40                                 }
  41                                 if (image == null)
  42                                         tile.set_status(AltosMapTile.failed);
  43                                 else
  44                                         tile.set_status(AltosMapTile.success);
  45                                 tile.notify_image(image);
  46                         }
  47                 }
  48
  49                 private void load() {
  50                         loader  l = new loader();
  51                         Thread  lt = new Thread(l);
  52                         lt.start();
  53                 }
  54
  55                 public void flush() {
  56                         if (image != null) {
  57                                 image.flush();
  58                                 image = null;
  59                         }
  60                 }
  61
  62                 public boolean has_map() {
  63                         return store.status() == AltosMapTile.success;
  64                 }
  65
  66                 public synchronized void notify_store(AltosMapStore store, int status) {
  67                         switch (status) {
  68                         case AltosMapTile.loading:
  69                                 break;
  70                         case AltosMapTile.success:
  71                                 load();
  72                                 break;
  73                         default:
  74                                 tile.set_status(status);
  75                                 tile.notify_image(null);
  76                         }
  77                 }
  78
  79                 public MapCacheElement(AltosMapTile tile, AltosMapStore store) throws IOException {
  80                         this.tile = tile;
  81                         this.image = null;
  82                         this.store = store;
  83                         this.used = 0;
  84
  85                         int status = store.status();
  86                         switch (status) {
  87                         case AltosMapTile.loading:
  88                                 store.add_listener(this);
  89                                 break;
  90                         case AltosMapTile.success:
  91                                 load();
  92                                 break;
  93                         default:
  94                                 tile.set_status(status);
  95                                 tile.notify_image(null);
  96                                 break;
  97                         }
  98                 }
  99         }
 100
 101         int                     min_cache_size;         /* configured minimum cache size */
 102         int                     cache_size;             /* current cache size */
 103         int                     requested_cache_size;   /* cache size computed by application */
 104
 105         private Object          fetch_lock = new Object();
 106         private Object          cache_lock = new Object();
 107
 108         AltosMapInterface       map_interface;
 109
 110         MapCacheElement[]       elements = new MapCacheElement[cache_size];
 111
 112         long                    used;
 113
 114         public void set_cache_size(int new_size) {
 115
 116                 requested_cache_size = new_size;
 117
 118                 if (new_size < min_cache_size)
 119                         new_size = min_cache_size;
 120
 121                 if (new_size == cache_size)
 122                         return;
 123
 124                 synchronized(cache_lock) {
 125                         MapCacheElement[]       new_elements = new MapCacheElement[new_size];
 126
 127                         for (int i = 0; i < cache_size; i++) {
 128                                 if (i < new_size)
 129                                         new_elements[i] = elements[i];
 130                                 else if (elements[i] != null)
 131                                         elements[i].flush();
 132                         }
 133                         elements = new_elements;
 134                         cache_size = new_size;
 135                 }
 136         }
 137
 138         public AltosImage get(AltosMapTile tile, AltosMapStore store, int width, int height) {
 139                 int             oldest = -1;
 140                 long            age = used;
 141
 142                 synchronized(cache_lock) {
 143                         MapCacheElement element = null;
 144                         for (int i = 0; i < cache_size; i++) {
 145                                 element = elements[i];
 146
 147                                 if (element == null) {
 148                                         oldest = i;
 149                                         break;
 150                                 }
 151                                 if (store.equals(element.store)) {
 152                                         element.used = used++;
 153                                         return element.image;
 154                                 }
 155                                 if (element.used < age) {
 156                                         oldest = i;
 157                                         age = element.used;
 158                                 }
 159                         }
 160
 161                         try {
 162                                 element = new MapCacheElement(tile, store);
 163                                 element.used = used++;
 164                                 if (elements[oldest] != null)
 165                                         elements[oldest].flush();
 166
 167                                 elements[oldest] = element;
 168
 169                                 if (element.image == null)
 170                                         tile.set_status(AltosMapTile.loading);
 171                                 else
 172                                         tile.set_status(AltosMapTile.success);
 173
 174                                 return element.image;
 175                         } catch (IOException e) {
 176                                 tile.set_status(AltosMapTile.failed);
 177                                 return null;
 178                         }
 179                 }
 180         }
 181
 182         public void map_cache_changed(int map_cache) {
 183                 min_cache_size = map_cache;
 184
 185                 set_cache_size(requested_cache_size);
 186         }
 187
 188         public void dispose() {
 189                 AltosPreferences.unregister_map_cache_listener(this);
 190
 191                 for (int i = 0; i < cache_size; i++) {
 192                         MapCacheElement element = elements[i];
 193
 194                         if (element != null)
 195                             element.flush();
 196                 }
 197         }
 198
 199         public AltosMapCache(AltosMapInterface map_interface) {
 200                 this.map_interface = map_interface;
 201                 min_cache_size = AltosPreferences.map_cache();
 202
 203                 set_cache_size(0);
 204
 205                 AltosPreferences.register_map_cache_listener(this);
 206         }
 207 }