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

Quick hack: Patching kernel modules using DKMS

05/05/2021

DKMS is a framework that is mostly used to build and install external kernel modules. It can also be used to install a specific patch to…

Build your own application with GTK 4 as a Meson subproject!

29/04/2021

Building GTK 4 as a Meson subproject for your own application is not only useful for Windows builds, but also for many Linux distributions…

Profiling virtualized GPU acceleration with Perfetto

22/04/2021

Recently, we have been using Perfetto to successfully profile Apitrace traces in crosvm through VirGL renderer. We have now added perfetto…

Continuous 3D Hand Pose Tracking using Machine Learning & Monado OpenXR

20/04/2021

As part of a project backed by INVEST-AI, a program managed by IVADO Labs, we have developed a multi-stage neural network-based solution…

An easy to use MTP implementation for your next embedded Linux project

13/04/2021

Did you know you could run a permissively-licensed MTP implementation with minimal dependencies on an embedded device? Here's a step-by-step…

Rust: integrating LLVM source-base code coverage with GitLab

24/03/2021

Earlier this year, the Rust compiler gained support for LLVM source-base code coverage. In this post we'll explain how to setup a CI job…

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 © 2005-2021. All rights reserved. Privacy Notice. Sitemap.

Collabora Limited is registered in England and Wales. Company Registration number: 5513718. Registered office: The Platinum Building, St John's Innovation Park, Cambridge, CB4 0DS, United Kingdom. VAT number: 874 1630 19.