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/api/DataEngineContext.java
return inputStream;
		}
		catch (IOException e)
		{
			throw new DataException( ResourceConstants.RD_LOAD_STREAM_ERROR, e );
		}
	}
	
	/**
	 * @param locale
	 *            The current task's locale
	 */
	public void setLocale( Locale locale )
	{
		currentLocale = ULocale.forLocale( locale );
		DataException.setLocale( currentLocale );
	}
	/**
	 * @return The current locale
	 */
	public ULocale getLocale( )
	{
		return currentLocale;
	}
	
	/**
	 * get Dte temporary dir.
	 * @return
	 */
	public String getTmpdir( )