Changeset 8860 in josm for trunk

Timestamp:

2015-10-11T22:43:40+02:00 (9 years ago)

Author:

wiktorn

Message:

Make MemoryTileCache instiated per-layer instead static.

Static MemoryTIleCache put quite a lot of pressure on the cache, esp. when
working with multiple layers. Instead of growing MemoryTileCache, small
instances per layer are implemented.

As MemoryTileCache might also put a lot pressure on memory, now size of
MemoryTileCache is calculated based on screen resolution, assuming, that user
will work in full screen mode. Implementation also checks, if all added layers
will not require more memory that is allocated for JOSM, to prevent unexpected
OutOfMemoryException.

Location:

trunk/src/org/openstreetmap/josm/gui/layer

Files:

• AbstractTileSourceLayer.java (modified) (6 diffs)
• Layer.java (modified) (2 diffs)

trunk/src/org/openstreetmap/josm/gui/layer/AbstractTileSourceLayer.java

@@ -151 +151 @@
      *  in MapView (for example - when limiting min zoom in imagery)
      *
-     *  Use static instance so memory is shared between layers to prevent out of memory exceptions, when user is working with many layers
-     */
-    protected static TileCache tileCache = new MemoryTileCache(MEMORY_CACHE_SIZE.get());
+     *  Use per-layer tileCache instance, as the more layers there are, the more tiles needs to be cached
+     */
+    protected TileCache tileCache; // initialized together with tileSource
     protected AbstractTMSTileSource tileSource;
     protected TileLoader tileLoader;
@@ -166 +166 @@
         this.setVisible(true);
         MapView.addZoomChangeListener(this);
+        this.tileSource = getTileSource(info);
+        if (this.tileSource == null) {
+            throw new IllegalArgumentException(tr("Failed to create tile source"));
+        }
     }
 
@@ -207 +211 @@
         if (tileLoader == null)
             tileLoader = new OsmTileLoader(this, headers);
+
+        tileCache = new MemoryTileCache(estimateTileCacheSize());
     }
 
@@ -506 +512 @@
     @Override
     public void hookUpMapView() {
-        this.tileSource = getTileSource(info);
-        if (this.tileSource == null) {
-            throw new IllegalArgumentException(tr("Failed to create tile source"));
-        }
-
+        super.hookUpMapView();
         projectionChanged(null, Main.getProjection()); // check if projection is supported
         initTileSource(this.tileSource);
@@ -660 +662 @@
     }
 
+    @Override
+    protected long estimateMemoryUsage() {
+        return 4L * tileSource.getTileSize() * tileSource.getTileSize() * estimateTileCacheSize();
+    }
+
+    protected int estimateTileCacheSize() {
+        int height = (int) Toolkit.getDefaultToolkit().getScreenSize().getHeight();
+        int width = (int) Toolkit.getDefaultToolkit().getScreenSize().getWidth();
+        int tileSize = 256; // default tile size
+        if (tileSource != null) {
+            tileSize = tileSource.getTileSize();
+        }
+        // as we can see part of the tile at the top and at the bottom, use Math.ceil(...) + 1 to accommodate for that
+        int visibileTiles = (int) (Math.ceil( (double)height / tileSize + 1) * Math.ceil((double)width / tileSize + 1));
+        // add 10% for tiles from different zoom levels
+        return (int)Math.ceil(
+                Math.pow(2d, ZOOM_OFFSET.get()) * visibileTiles // use offset to decide, how many tiles are visible
+                * 2);
+    }
     /**
      * Checks zoom level against settings
@@ -1510 +1531 @@
             myDrawString(g, tr("Pixel scale: {0}", getScaleFactor(currentZoomLevel)), 50, 170);
             myDrawString(g, tr("Best zoom: {0}", getBestZoom()), 50, 185);
+            myDrawString(g, tr("Estimated cache size: {0}", estimateTileCacheSize()), 50, 200);
             if (tileLoader instanceof TMSCachedTileLoader) {
                 TMSCachedTileLoader cachedTileLoader = (TMSCachedTileLoader) tileLoader;
-                int offset = 185;
+                int offset = 200;
                 for (String part: cachedTileLoader.getStats().split("\n")) {
                     myDrawString(g, tr("Cache stats: {0}", part), 50, offset += 15);

trunk/src/org/openstreetmap/josm/gui/layer/Layer.java

@@ -138 +138 @@
      * not execute code in the constructor, that assumes Main.map.mapView is
      * not null. Instead override this method.
+     *
+     * This implementation provides check, if JOSM will be able to use Layer. Layers
+     * using a lot of memory, which do know in advance, how much memory they use, should
+     * override {@link #estimateMemoryUsage() estimateMemoryUsage} method and give a hint.
+     *
+     * This allows for preemptive warning message for user, instead of failing later on
+     *
+     * Remember to call {@code super.hookUpMapView()} when overriding this method
      */
     public void hookUpMapView() {
+        // calculate total memory needed for all layers
+        long memoryBytesRequired = 50 * 1024 * 1024; // assumed minimum JOSM memory footprint
+        if (Main.map != null && Main.map.mapView != null) {
+            for (Layer layer: Main.map.mapView.getAllLayers()) {
+                memoryBytesRequired += layer.estimateMemoryUsage();
+            }
+            if (memoryBytesRequired >  Runtime.getRuntime().maxMemory()) {
+                throw new IllegalArgumentException(tr("To add another layer you need to allocate at least {0,number,#}MB memory to JOSM using -Xmx{0,number,#}M "
+                        + "option (see http://forum.openstreetmap.org/viewtopic.php?id=25677).\n"
+                        + "Currently you have {1,number,#}MB memory allocated for JOSM", memoryBytesRequired / 1024 / 1024, Runtime.getRuntime().maxMemory() / 1024 / 1024));
+            }
+        }
     }
 
@@ -507 +527 @@
         return SaveActionBase.createAndOpenSaveFileChooser(tr("Save Layer"), "lay");
     }
+
+    /**
+     * @return bytes that the tile will use. Needed for resource management
+     */
+    protected long estimateMemoryUsage() {
+        return 0;
+    }
 }