Bug 206861 The data set cache should handle IOException and the cancel request from customer
The data set data will be saved into disk file in the first query and it will be loaded in the later time. The processing of write disk file may be cancelled by customer request or IOException. Using the data from the bad file will cause error.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/executor/cache/disk/DiskDataExport.java
dbExport = new DiskSortExport2( infoMap, comparator, resultObjectUtil );
		else
			dbExport = new DiskDirectExport( infoMap, resultObjectUtil );
		dbExport.resultObjectUtil = resultObjectUtil;
		return dbExport;
	}
	
	/**
	 * Export data which is stored in the resultObjects array to disk, which is
	 * the first step of export.
	 * 
	 * @param rs
	 * @param stopSign
	 * @throws IOException, file writer exception
	 */
	public abstract void exportStartDataToDisk( IResultObject[] resultObjects, StopSign stopSign )
			throws IOException;
	
	/**
	 * Export data which is fetched form RowResultSet, which is the second step
	 * of export following the first step of exportStartDataToDisk.
	 * 
	 * @param resultObject, the start resultObject
	 * @param rs, follows the resultObject
	 * @param stopSign
	 * @throws DataException, fetch data exception
	 * @throws IOException, file writer exception
	 */
	public abstract int exportRestDataToDisk( IResultObject resultObject,
			IRowResultSet rs, StopSign stopSign ) throws DataException, IOException;