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_11;
  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 AltosMapTileListener {
  27
  28                 AltosMapTile            tile;           /* Notify when image has been loaded */
  29                 AltosImage              image;
  30                 long                    used;
  31
  32                 class loader implements Runnable {
  33                         public void run() {
  34                                 if (image == null) {
  35                                         try {
  36                                                 image = map_interface.load_image(tile.store.file);
  37                                         } catch (Exception ex) {
  38                                         }
  39                                 }
  40                                 tile.notify_image(image);
  41                         }
  42                 }
  43
  44                 private void load() {
  45                         loader  l = new loader();
  46                         Thread  lt = new Thread(l);
  47                         lt.start();
  48                 }
  49
  50                 public void flush() {
  51                         if (image != null) {
  52                                 image.flush();
  53                                 image = null;
  54                         }
  55                 }
  56
  57                 public boolean has_map() {
  58                         return tile.status == AltosMapTile.loaded;
  59                 }
  60
  61                 public synchronized void notify_tile(AltosMapTile tile, int status) {
  62                         if (status == AltosMapTile.fetched) {
  63                                 load();
  64                         }
  65                 }
  66
  67                 public MapCacheElement(AltosMapTile tile) {
  68                         this.tile = tile;
  69                         this.image = null;
  70                         this.used = 0;
  71                         tile.add_listener(this);
  72                 }
  73         }
  74
  75         int                     min_cache_size;         /* configured minimum cache size */
  76         int                     cache_size;             /* current cache size */
  77         int                     requested_cache_size;   /* cache size computed by application */
  78
  79         private Object          fetch_lock = new Object();
  80         private Object          cache_lock = new Object();
  81
  82         AltosMapInterface       map_interface;
  83
  84         MapCacheElement[]       elements = new MapCacheElement[cache_size];
  85
  86         long                    used;
  87
  88         public void set_cache_size(int new_size) {
  89
  90                 requested_cache_size = new_size;
  91
  92                 if (new_size < min_cache_size)
  93                         new_size = min_cache_size;
  94
  95                 if (new_size == cache_size)
  96                         return;
  97
  98                 synchronized(cache_lock) {
  99                         MapCacheElement[]       new_elements = new MapCacheElement[new_size];
 100
 101                         for (int i = 0; i < cache_size; i++) {
 102                                 if (i < new_size)
 103                                         new_elements[i] = elements[i];
 104                                 else if (elements[i] != null)
 105                                         elements[i].flush();
 106                         }
 107                         elements = new_elements;
 108                         cache_size = new_size;
 109                 }
 110         }
 111
 112         public AltosImage get(AltosMapTile tile) {
 113                 int             oldest = -1;
 114                 long            age = used;
 115
 116                 synchronized(cache_lock) {
 117                         MapCacheElement element = null;
 118                         for (int i = 0; i < cache_size; i++) {
 119                                 element = elements[i];
 120
 121                                 if (element == null) {
 122                                         oldest = i;
 123                                         break;
 124                                 }
 125                                 if (tile.store.equals(element.tile.store)) {
 126                                         element.used = used++;
 127                                         return element.image;
 128                                 }
 129                                 if (element.used < age) {
 130                                         oldest = i;
 131                                         age = element.used;
 132                                 }
 133                         }
 134
 135                         element = new MapCacheElement(tile);
 136                         element.used = used++;
 137                         if (elements[oldest] != null)
 138                                 elements[oldest].flush();
 139
 140                         elements[oldest] = element;
 141                         return element.image;
 142                 }
 143         }
 144
 145         public void map_cache_changed(int map_cache) {
 146                 min_cache_size = map_cache;
 147
 148                 set_cache_size(requested_cache_size);
 149         }
 150
 151         public void dispose() {
 152                 AltosPreferences.unregister_map_cache_listener(this);
 153
 154                 for (int i = 0; i < cache_size; i++) {
 155                         MapCacheElement element = elements[i];
 156
 157                         if (element != null)
 158                             element.flush();
 159                 }
 160         }
 161
 162         public AltosMapCache(AltosMapInterface map_interface) {
 163                 this.map_interface = map_interface;
 164                 min_cache_size = AltosPreferences.map_cache();
 165
 166                 set_cache_size(0);
 167
 168                 AltosPreferences.register_map_cache_listener(this);
 169         }
 170 }