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/DataSetCacheManager.java
dataSetDesign,
				parameterHints,
				appContext);
		return cacheMapManager.doesLoadFromCache( DataSourceAndDataSet.newInstance( this.dataSourceDesign,
				dataSetDesign,
				parameterHints ) );
	}
	/**
	 * @param dataSetDesign
	 * @param cacheOption
	 * @param alwaysCacheRowCount
	 * @return
	 */
	public boolean needsToCache( IBaseDataSetDesign dataSetDesign,
			int cacheOption, int alwaysCacheRowCount )
	{
		return DataSetCacheUtil.needsToCache( dataSetDesign,
				cacheOption,
				alwaysCacheRowCount );
	}
	/**
	 * @return
	 */
	public int getCacheRowCount( )
	{
		return DataSetCacheUtil.getCacheRowCount( cacheOption,
				alwaysCacheRowCount,
				this.dataSetDesign == null ? 0
						: this.dataSetDesign.getCacheRowCount( ) );
	}