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/*
* Copyright © 2010 Anthony Towns <aj@erisian.com.au>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*/
package org.altusmetrum.altoslib_11;
import java.io.*;
import java.net.*;
public class AltosMapCache implements AltosMapCacheListener {
/* An entry in the MapCache */
class MapCacheElement implements AltosMapTileListener {
AltosMapTile tile; /* Notify when image has been loaded */
AltosImage image;
long used;
class loader implements Runnable {
public void run() {
if (image == null) {
try {
image = map_interface.load_image(tile.store.file);
} catch (Exception ex) {
}
}
tile.notify_image(image);
}
}
private void load() {
loader l = new loader();
Thread lt = new Thread(l);
lt.start();
}
public void flush() {
if (image != null) {
image.flush();
image = null;
}
}
public boolean has_map() {
return tile.status == AltosMapTile.loaded;
}
public synchronized void notify_tile(AltosMapTile tile, int status) {
if (status == AltosMapTile.fetched) {
load();
}
}
public MapCacheElement(AltosMapTile tile) {
this.tile = tile;
this.image = null;
this.used = 0;
tile.add_listener(this);
}
}
int min_cache_size; /* configured minimum cache size */
int cache_size; /* current cache size */
int requested_cache_size; /* cache size computed by application */
private Object fetch_lock = new Object();
private Object cache_lock = new Object();
AltosMapInterface map_interface;
MapCacheElement[] elements = new MapCacheElement[cache_size];
long used;
public void set_cache_size(int new_size) {
requested_cache_size = new_size;
if (new_size < min_cache_size)
new_size = min_cache_size;
if (new_size == cache_size)
return;
synchronized(cache_lock) {
MapCacheElement[] new_elements = new MapCacheElement[new_size];
for (int i = 0; i < cache_size; i++) {
if (i < new_size)
new_elements[i] = elements[i];
else if (elements[i] != null)
elements[i].flush();
}
elements = new_elements;
cache_size = new_size;
}
}
public AltosImage get(AltosMapTile tile) {
int oldest = -1;
long age = used;
synchronized(cache_lock) {
MapCacheElement element = null;
for (int i = 0; i < cache_size; i++) {
element = elements[i];
if (element == null) {
oldest = i;
break;
}
if (tile.store.equals(element.tile.store)) {
element.used = used++;
return element.image;
}
if (element.used < age) {
oldest = i;
age = element.used;
}
}
element = new MapCacheElement(tile);
element.used = used++;
if (elements[oldest] != null)
elements[oldest].flush();
elements[oldest] = element;
return element.image;
}
}
public void map_cache_changed(int map_cache) {
min_cache_size = map_cache;
set_cache_size(requested_cache_size);
}
public void dispose() {
AltosPreferences.unregister_map_cache_listener(this);
for (int i = 0; i < cache_size; i++) {
MapCacheElement element = elements[i];
if (element != null)
element.flush();
}
}
public AltosMapCache(AltosMapInterface map_interface) {
this.map_interface = map_interface;
min_cache_size = AltosPreferences.map_cache();
set_cache_size(0);
AltosPreferences.register_map_cache_listener(this);
}
}
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