- * This is for putting a breakpoint onto, when debugging. It is called
- * when a conn with io_set_debug() true can no longer be synchronous:
- * 1) It is io_close()'d
- * 2) It enters io_wait() (sychronous debug will resume after io_wake())
- * 3) io_break() is called (sychronous debug will resume after io_loop())
+ * This is generally used as an emergency escape, for example when we
+ * want to write an error message on a socket before terminating, but it may
+ * be in the middle of existing I/O. We don't want to service any other
+ * IO, either.
+ *
+ * This returns true if all pending output is complete, false on error.
+ * The next callback is not called on the conn, but will be as soon as
+ * io_loop() is called.
+ *
+ * See Also:
+ * io_close_taken_fd
+ */
+bool io_flush_sync(struct io_conn *conn);
+
+/**
+ * io_conn_exclusive - set/unset an io_conn to exclusively serviced
+ * @conn: the connection
+ * @exclusive: whether to be exclusive or not
+ *
+ * If any io_conn is set exclusive, then no non-exclusive io_conn (or
+ * io_listener) will be serviced by io_loop(). If it's a io_duplex io_conn(),
+ * then io_conn_exclusive() makes the read-side exclusive; io_conn_out_exclusive()
+ * makes the write-side exclusive.
+ *
+ * This allows you to temporarily service only one (or several) fds.
+ * For example, you might want to flush out one io_conn and not
+ * receive any new connections or read any otherninput.
+ *
+ * Returns true of there any exclusive io_conn remain, otherwise false.
+ * (This is useful for checking your own logic: dangling exclusive io_conn
+ * are dangerous!).
+ */
+bool io_conn_exclusive(struct io_conn *conn, bool exclusive);
+
+/**
+ * io_conn_out_exclusive - set/unset exclusive on the write-side of a duplex
+ * @conn: the connection, post io_duplex
+ * @exclusive: whether to be exclusive or not
+ *
+ * See io_conn_exclusive() above.