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
{
				rowCount++;
				roUtil.writeData( bos, resultObject );
			}
			catch ( IOException e )
			{
				throw new DataException( ResourceConstants.DATASETCACHE_SAVE_ERROR,
						e );
			}
		}
		/**
		 * Write the new data to the local file and close the I/O operation
		 * 
		 * @throws DataException
		 */
		private void close( ) throws DataException
		{
			try
			{
				if ( bos != null )
				{
					bos.close( );
					fos.close( );
				}
				FileOutputStream fos1 = new FileOutputStream( metaFile );
				BufferedOutputStream bos1 = new BufferedOutputStream( fos1 );
				
				IOUtil.writeInt( bos1, this.rowCount );
				
				Map metaMap = new HashMap( );