Initial Commit - Copy from Altus Metrum AltOS

altoslib/AltosMapCache.java

@@ -0,0 +1,171 @@
+/*
+ * 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_14;
+
+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);
+	}
+}