+ /* Allows 'stream' to perform maintenance activities, such as flushing
+ * output buffers.
+ *
+ * May be null if 'stream' doesn't have anything to do here. */
+ void (*run)(struct stream *stream);
+
+ /* Arranges for the poll loop to wake up when 'stream' needs to perform
+ * maintenance activities.
+ *
+ * May be null if 'stream' doesn't have anything to do here. */
+ void (*run_wait)(struct stream *stream);
+