added method for database cache file size retrieval

@@ -73,4 +73,7 @@
 *   @param theExpiryPeriod The amount of time to elapse before a tile should be removed from the cache. If set to zero, tile count-based purging will be used instead of time-based. */
 - (void)setExpiryPeriod:(NSTimeInterval)theExpiryPeriod;
 
+/** The current file size of the database cache on disk. */
+- (unsigned long long)fileSize;
+
 @end

@@ -178,6 +178,11 @@
     srand(time(NULL));
 }
 
+- (unsigned long long)fileSize
+{
+    return [[[NSFileManager defaultManager] attributesOfItemAtPath:self.databasePath error:nil] fileSize];
+}
+
 - (UIImage *)cachedImage:(RMTile)tile withCacheKey:(NSString *)aCacheKey
 {
 //	RMLog(@"DB cache check for tile %d %d %d", tile.x, tile.y, tile.zoom);