+ /*! take a vector of s4u::IoPtr and return when one of them is finished.
+ * The return value is the rank of the first finished IoPtr. */
+ static ssize_t wait_any(const std::vector<IoPtr>& ios) { return wait_any_for(ios, -1); }
+ /*! Same as wait_any, but with a timeout. If the timeout occurs, parameter last is returned.*/
+ static ssize_t wait_any_for(const std::vector<IoPtr>& ios, double timeout);