public ScanWriter createScanWriter ( final int taskId , Set < ScanDestination > destinations ) { checkArgument ( ! destinations . isEmpty ( ) , "destinations.isEmpty()" ) ; if ( destinations . size ( ) == 1 ) { return createScanWriter ( taskId , Iterables . getOnlyElement ( destinations ) ) ; } return new MultiScanWriter ( ImmutableList . copyOf ( Iterables . transform ( destinations , new Function < ScanDestination , ScanWriter > ( ) { @ Override public ScanWriter apply ( ScanDestination destination ) { return createScanWriter ( taskId , destination ) ; } } ) ) ) ; }
Creates a scan writer from the given desintations .