We're hiring!
*

GLib now has a datagram interface

Philip Withnall avatar

Philip Withnall
October 13, 2015

Share this post:

For those who like their I/O packetised, GLib now has a companion for its GIOStream class — the GDatagramBasedinterface, which we’ve implemented as part of R&D work at Collabora. This is designed to be implemented by any class which does datagram-based I/O. GSocket implements it, essentially as an interface to recvmmsg() and sendmmsg(). The upcoming DTLS support in glib-networking will use it.

How is it shaped? Basically as a GLib-shaped version of recvmmsg() and sendmmsg(), where GInputMessage and GOutputMessage are effectively equivalent to struct mmsghdr, and GInputVector and GOutputVector are equivalent to struct msghdr.

The interface is designed around polling, potentially-blocking I/O. What’s ‘potentially-blocking’ about it? The timeout parameter. Set it to zero for non-blocking behaviour, where the functions will return G_IO_ERROR_WOULD_BLOCK if they would block. Set it negative for blocking behaviour, where the functions will not return until they can do at least some I/O. Set it positive for timeout behaviour, where the functions will block for the given number of microseconds, then return G_IO_ERROR_TIMED_OUT if they managed to perform no I/O.

gint
g_datagram_based_receive_messages (GDatagramBased   *datagram_based,
                                   GInputMessage    *messages,
                                   guint             num_messages,
                                   gint              flags,
                                   gint64            timeout,
                                   GCancellable     *cancellable,
                                   GError          **error);
 
gint
g_datagram_based_send_messages    (GDatagramBased   *datagram_based,
                                   GOutputMessage   *messages,
                                   guint             num_messages,
                                   gint              flags,
                                   gint64            timeout,
                                   GCancellable     *cancellable,
                                   GError          **error);
 
GSource *
g_datagram_based_create_source    (GDatagramBased   *datagram_based,
                                   GIOCondition      condition,
                                   GCancellable     *cancellable);
GIOCondition
g_datagram_based_condition_check  (GDatagramBased   *datagram_based,
                                   GIOCondition      condition);
gboolean
g_datagram_based_condition_wait   (GDatagramBased   *datagram_based,
                                   GIOCondition      condition,
                                   gint64            timeout,
                                   GCancellable     *cancellable,
                                   GError          **error);
 

Currently, the API (particularly GInputMessage and GOutputMessage, due to the way they are used as in-out parameters) doesn’t support introspection. This can be added in future if needed by creating some convenience API for allocating and freeing the message structures as boxed types.

The grand, overarching plan is for this to appear in a libnice version near you, some time soon, exposing the whole of an ICE connection as a GDatagramBased.

If you think the name is bad, tough. It has been bikeshedded enough already.

Related Posts

Related Posts

Comments (0)


Add a Comment






Allowed tags: <b><i><br>Add a new comment:


Search the newsroom

Latest Blog Posts

syzkaller: fuzzing the kernel

26/03/2020

With the code base of the Linux kernel constantly changing and deployed in devices around the world, performing proper testing is crucial.…

Getting started with GStreamer's gst-build

19/03/2020

GStreamer relies on multiple repositories such as base and good to build its ecosystem, and now owns more than 30 projects in Gitlab. So,…

Why remote working can be good for people, business and environment

10/03/2020

Here at Collabora, we trust our people to work remotely, we give them full responsibility for their output, and we believe it helps creating…

PipeWire, the media service transforming the Linux multimedia landscape

05/03/2020

PipeWire 0.3 was released a few days ago, marking a big step forward in the effort of making this emerging media service the core layer…

Experimental Panfrost GLES 3.0 support has landed in Mesa

27/02/2020

Panfrost's ES 3.0 support has landed in upstream Mesa and works with a mainline Linux kernel. The support is still early, but if you're…

Using gcc sanitisers to get a nasty bug fixed

18/02/2020

When a bug surprises you when doing Apertis packaging of a typical vendor code signing tool, it's time to debug it using the compiler's…

Open Since 2005 logo

We use cookies on this website to ensure that you get the best experience. By continuing to use this website you are consenting to the use of these cookies. To find out more please follow this link.

Collabora Ltd © 2005-2020. All rights reserved. Website sitemap.