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/executor/CacheMapManager.java
}
	/**
	 * @return
	 */
	String getSaveFolder( DataSourceAndDataSet dsAndDs )
	{
		return (String) cacheMap.get( dsAndDs );
	}
	/**
	 * @return
	 */
	String getLoadFolder( DataSourceAndDataSet dsAndDs )
	{
		return (String) cacheMap.get( dsAndDs );
	}
	/**
	 * @param dataSourceDesign2
	 * @param dataSetDesign2
	 */
	void clearCache( DataSourceAndDataSet dsAndDs )
	{
		List cacheDir = new ArrayList( );
		synchronized ( cacheMap )
		{
			while ( getKey( dsAndDs ) != null )
			{
				cacheDir.add( cacheMap.remove( getKey( dsAndDs ) ) );
			}
		}
		for ( int i = 0; i < cacheDir.size( ); i++ )