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.tests/test/org/eclipse/birt/data/engine/binding/DataSetCacheTest.java
* @throws BirtException
	 */
	public void testDisableCache( ) throws BirtException
	{
		DataEngineContext context = DataEngineContext.newInstance( DataEngineContext.DIRECT_PRESENTATION,
				null,
				null,
				null );
		context.setCacheOption( DataEngineContext.CACHE_USE_DISABLE, 4 );
		DataEngineImpl myDataEngine2 = (DataEngineImpl) DataEngine.newDataEngine( context );
		myDataEngine2.defineDataSource( this.dataSource );
		myDataEngine2.defineDataSet( this.dataSet );
		QueryDefinition qd = newReportQuery( );
		IQueryResults qr = myDataEngine2.prepare( qd ).execute( null );
		assertFalse( getDataSetCacheManager( myDataEngine2 ).doesLoadFromCache( ) );
		qr.getResultIterator( );
		assertFalse( getDataSetCacheManager( myDataEngine2 ).doesLoadFromCache( ) );
		qr.close( );
		myDataEngine2.shutdown( );
	}
	/**
	 * Test the feature of cache. Check the data in between the cache use is corret.
	 *@throws BirtException
	 */
	public void testOdaCache( ) throws BirtException
	{
		genCache( );
		useCache( );
	}
	/**