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.appContextMap.put( DataEngine.DATA_SET_CACHE_ROW_LIMIT, new Integer( 1 ) );
		this.genCache();
		DataEngine myDataEngine = newDataEngine( );
		IResultMetaData meta = myDataEngine.getCachedDataSetMetaData(dataSource, dataSet);
		assertTrue( meta!= null );
		assertTrue( meta.getColumnCount() == 6 );
	}
	
	/**
	 * Test acqurire inexist save cache result meta 
	 *
	 */
	public void testUseCachedMeta2() throws BirtException
	{
		this.appContextMap.put( DataEngine.DATA_SET_CACHE_ROW_LIMIT, new Integer( 0 ) );
		this.genCache();
		DataEngine myDataEngine = newDataEngine( );
		IResultMetaData meta = myDataEngine.getCachedDataSetMetaData(dataSource, dataSet);
		assertTrue( meta == null );
	}
	
	/**
	 * Test feature of whether cache will be used. The populated computed name
	 * contains blank space and quotes.
	 * 
	 * @throws BirtException
	 */
	public void testUseCache3( ) throws BirtException
	{