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; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  17  */
  18
  19 package org.altusmetrum.altoslib_12;
  20
  21 import java.io.*;
  22 import java.net.*;
  23
  24 public class AltosMapCache implements AltosMapCacheListener {
  25
  26         /* An entry in the MapCache */
  27         class MapCacheElement implements AltosMapTileListener {
  28
  29                 AltosMapTile            tile;           /* Notify when image has been loaded */
  30                 AltosImage              image;
  31                 long                    used;
  32
  33                 class loader implements Runnable {
  34                         public void run() {
  35                                 if (image == null) {
  36                                         try {
  37                                                 image = map_interface.load_image(tile.store.file);
  38                                         } catch (Exception ex) {
  39                                         }
  40                                 }
  41                                 tile.notify_image(image);
  42                         }
  43                 }
  44
  45                 private void load() {
  46                         loader  l = new loader();
  47                         Thread  lt = new Thread(l);
  48                         lt.start();
  49                 }
  50
  51                 public void flush() {
  52                         if (image != null) {
  53                                 image.flush();
  54                                 image = null;
  55                         }
  56                 }
  57
  58                 public boolean has_map() {
  59                         return tile.status == AltosMapTile.loaded;
  60                 }
  61
  62                 public synchronized void notify_tile(AltosMapTile tile, int status) {
  63                         if (status == AltosMapTile.fetched) {
  64                                 load();
  65                         }
  66                 }
  67
  68                 public MapCacheElement(AltosMapTile tile) {
  69                         this.tile = tile;
  70                         this.image = null;
  71                         this.used = 0;
  72                         tile.add_listener(this);
  73                 }
  74         }
  75
  76         int                     min_cache_size;         /* configured minimum cache size */
  77         int                     cache_size;             /* current cache size */
  78         int                     requested_cache_size;   /* cache size computed by application */
  79
  80         private Object          fetch_lock = new Object();
  81         private Object          cache_lock = new Object();
  82
  83         AltosMapInterface       map_interface;
  84
  85         MapCacheElement[]       elements = new MapCacheElement[cache_size];
  86
  87         long                    used;
  88
  89         public void set_cache_size(int new_size) {
  90
  91                 requested_cache_size = new_size;
  92
  93                 if (new_size < min_cache_size)
  94                         new_size = min_cache_size;
  95
  96                 if (new_size == cache_size)
  97                         return;
  98
  99                 synchronized(cache_lock) {
 100                         MapCacheElement[]       new_elements = new MapCacheElement[new_size];
 101
 102                         for (int i = 0; i < cache_size; i++) {
 103                                 if (i < new_size)
 104                                         new_elements[i] = elements[i];
 105                                 else if (elements[i] != null)
 106                                         elements[i].flush();
 107                         }
 108                         elements = new_elements;
 109                         cache_size = new_size;
 110                 }
 111         }
 112
 113         public AltosImage get(AltosMapTile tile) {
 114                 int             oldest = -1;
 115                 long            age = used;
 116
 117                 synchronized(cache_lock) {
 118                         MapCacheElement element = null;
 119                         for (int i = 0; i < cache_size; i++) {
 120                                 element = elements[i];
 121
 122                                 if (element == null) {
 123                                         oldest = i;
 124                                         break;
 125                                 }
 126                                 if (tile.store.equals(element.tile.store)) {
 127                                         element.used = used++;
 128                                         return element.image;
 129                                 }
 130                                 if (element.used < age) {
 131                                         oldest = i;
 132                                         age = element.used;
 133                                 }
 134                         }
 135
 136                         element = new MapCacheElement(tile);
 137                         element.used = used++;
 138                         if (elements[oldest] != null)
 139                                 elements[oldest].flush();
 140
 141                         elements[oldest] = element;
 142                         return element.image;
 143                 }
 144         }
 145
 146         public void map_cache_changed(int map_cache) {
 147                 min_cache_size = map_cache;
 148
 149                 set_cache_size(requested_cache_size);
 150         }
 151
 152         public void dispose() {
 153                 AltosPreferences.unregister_map_cache_listener(this);
 154
 155                 for (int i = 0; i < cache_size; i++) {
 156                         MapCacheElement element = elements[i];
 157
 158                         if (element != null)
 159                             element.flush();
 160                 }
 161         }
 162
 163         public AltosMapCache(AltosMapInterface map_interface) {
 164                 this.map_interface = map_interface;
 165                 min_cache_size = AltosPreferences.map_cache();
 166
 167                 set_cache_size(0);
 168
 169                 AltosPreferences.register_map_cache_listener(this);
 170         }
 171 }