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
{
		
		private String tempRootDirStr = null;
		/**
		 * @return temp root dir directory
		 */
		private void createTempRootDir( )
		{
			if ( tempRootDirStr != null
					&& new File( tempRootDirStr ).exists( ) == true )
				return;
			File tempDtEDir = null;
			
			synchronized ( cacheCounter1 )
			{
				tempDtEDir = new File( tempDir, "BirtDataCache"
						+ System.currentTimeMillis( ) + cacheCounter1 );
				cacheCounter1 = new Integer( cacheCounter1.intValue( ) + 1 );
				int x = 0;
				while ( tempDtEDir.exists( ) )
				{
					x++;
					tempDtEDir = new File( tempDir, "BirtDataCache"
							+ System.currentTimeMillis( ) + cacheCounter1 + "_"
							+ x );
				}