Bug 180189 Support in memory data set cache.
Currently, Design-Time Data Cache is stored on disks. By performance tests using ramdisk, we found that caching in physical memory can improve the performance of RunAndRender by 30%.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/executor/DataSetCacheManager.java
{
				throw new DataException( ResourceConstants.DATASETCACHE_LOAD_ERROR,
						e );
			}
		}
		/**
		 * To save each ResultObject
		 * 
		 * @param resultObject
		 * @throws DataException
		 */
		private void saveObject( IResultObject resultObject )
				throws DataException
		{
			assert resultObject != null;
			if ( roUtil == null )
			{
				roUtil = ResultObjectUtil.newInstance( rsClass );
				try
				{
					fos = new FileOutputStream( dataFile, true );
					bos = new BufferedOutputStream( fos );
				}
				catch ( FileNotFoundException e )
				{
					throw new DataException( ResourceConstants.DATASETCACHE_SAVE_ERROR,
							e );
				}
			}
			try