Omaha #2866 Calculate subgrid size to limit response sizes

Change-Id: I3ccc8f7fa6e63f9bf5bf3bc7487aa38df3cc76c1

Former-commit-id: 6620a7bdc7da9d1c2edcb49b710db425f5a1c110

edexOsgi/com.raytheon.uf.common.dataplugin.gfe/src/com/raytheon/uf/common/dataplugin/gfe/dataaccess/GFEGridFactory.java

@@ -74,6 +74,7 @@ import com.raytheon.uf.common.util.StringUtil;
  * Oct 31, 2013  2508     randerso    Change to use DiscreteGridSlice.getKeys()
  * Feb 04, 2014  2672     bsteffen    Enable requesting subgrids.
  * Jul 30, 2014  3184     njensen     Renamed valid identifiers to optional
+ * Feb 10, 2015  2866     nabowle     Overwrite subgrid size estimation.
  *
  * </pre>
  *
@@ -204,6 +205,22 @@ public class GFEGridFactory extends AbstractGridDataPluginFactory implements
         return constraints;
     }
 
+    /**
+     * Estimates the subgrid memory size using the grid geometry's size because
+     * {@link #getDataSource(PluginDataObject, SubGridGeometryCalculator)} uses
+     * an {@link OffsetDataSource} that holds the full grid data in memory.
+     * 
+     * @param gridGeom
+     * @param subGrid
+     * @return
+     */
+    protected long estimateSubgridSize(GridGeometry2D gridGeom,
+            SubGridGeometryCalculator subGrid) {
+        long size = gridGeom.getGridRange().getSpan(0)
+                * gridGeom.getGridRange().getSpan(1);
+        return size;
+    }
+
     @Override
     protected DataSource getDataSource(PluginDataObject pdo,
             SubGridGeometryCalculator subGrid) {