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
this.dataSet.setCacheRowCount( 4 );
		DataEngine myDataEngine = newDataEngine( );
		IResultIterator parentRi = getResultIterator1( myDataEngine );
		parentRi.next( );
		IResultIterator ri = parentRi.getSecondaryIterator( "IAMTEST", scope );;
		while ( ri.next( ) )
		{
			expectedValue.add( ri.getValue( "COL1" ) );
		}
		assertEquals( expectedValue.size( ), 1 );
		ri.close( );
		parentRi.close( );
		myDataEngine.shutdown( );
	}
	/**
	 * @throws BirtException
	 */
	private void useCache( ) throws BirtException
	{
		DataEngine myDataEngine = newDataEngine( );
		IResultIterator ri = getResultIterator1( myDataEngine );
		checkResult( ri );
		ri.close( );
		myDataEngine.shutdown( );
	}
	/**
	 * @throws BirtException
	 */
	private void useCache3( ) throws BirtException
	{