gstreamer/gst-libs/gst/gl/wayland/wayland_event_source.c
Matthew Waters 2763baf439 gl/wayland: use multi-threaded safe event wayland API
Multiple threads may be accessing the wayland fd at the same time which
requires the use of special wayland API to deal with to ensure nobody
will steal reads and cause a stall for anyone else.
2017-12-09 19:32:22 +00:00

204 lines
5.2 KiB
C

/*
* GStreamer
* Copyright (C) 2010 Intel Corporation.
* Copyright (C) 2012 Matthew Waters <ystreet00@gmail.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
* Authors:
* Matthew Allum
* Robert Bragg
* Kristian Høgsberg
*/
/* code originally from clutter's wayland backend found here
* http://git.gnome.org/browse/clutter/tree/clutter/wayland/clutter-event-wayland.c
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdint.h>
#include <stdlib.h>
#include <wayland-client.h>
#include "wayland_event_source.h"
static void
sync_callback (void *data, struct wl_callback *callback, uint32_t serial)
{
gboolean *done = data;
*done = TRUE;
wl_callback_destroy (callback);
}
static const struct wl_callback_listener sync_listener = {
sync_callback
};
/* only thread safe iff called on the same thread @queue is being dispatched on */
gint
gst_gl_wl_display_roundtrip_queue (struct wl_display *display,
struct wl_event_queue *queue)
{
struct wl_callback *callback;
gboolean done = FALSE;
gint ret = 0;
if (queue) {
/* creating a wl_proxy and setting the queue is racy with the dispatching
* of the default queue */
while (wl_display_prepare_read_queue (display, queue) != 0) {
if ((ret = wl_display_dispatch_queue_pending (display, queue)) < 0)
return ret;
}
}
if (!(callback = wl_display_sync (display))) {
return -1;
}
wl_callback_add_listener (callback, &sync_listener, &done);
if (queue) {
wl_proxy_set_queue ((struct wl_proxy *) callback, queue);
wl_display_cancel_read (display);
while (!done && ret >= 0)
ret = wl_display_dispatch_queue (display, queue);
} else {
while (!done && ret >= 0)
ret = wl_display_dispatch (display);
}
if (ret == -1 && !done)
wl_callback_destroy (callback);
return ret;
}
typedef struct _WaylandEventSource
{
GSource source;
GPollFD pfd;
uint32_t mask;
struct wl_display *display;
struct wl_event_queue *queue;
gboolean reading;
} WaylandEventSource;
static gboolean
wayland_event_source_prepare (GSource * base, gint * timeout)
{
WaylandEventSource *source = (WaylandEventSource *) base;
*timeout = -1;
/* we may be called multiple times for prepare */
if (source->reading)
wl_display_cancel_read (source->display);
if (source->queue) {
while (wl_display_prepare_read_queue (source->display, source->queue) != 0) {
if (wl_display_dispatch_queue_pending (source->display,
source->queue) < 0) {
g_critical ("Failed to dispatch pending events\n");
}
}
} else {
while (wl_display_prepare_read (source->display) != 0) {
if (wl_display_dispatch_pending (source->display) < 0) {
g_critical ("Failed to dispatch pending events\n");
}
}
}
source->reading = TRUE;
/* FIXME: this may return EAGAIN if the fd is full */
if (wl_display_flush (source->display) < 0)
g_critical ("Failed to flush Wayland connection\n");
return FALSE;
}
static gboolean
wayland_event_source_check (GSource * base)
{
WaylandEventSource *source = (WaylandEventSource *) base;
gboolean retval;
retval = source->pfd.revents;
if (source->pfd.revents & G_IO_IN) {
wl_display_read_events (source->display);
} else {
wl_display_cancel_read (source->display);
}
source->reading = FALSE;
return retval;
}
static gboolean
wayland_event_source_dispatch (GSource * base,
GSourceFunc callback, gpointer data)
{
WaylandEventSource *source = (WaylandEventSource *) base;
if (source->queue)
wl_display_dispatch_queue_pending (source->display, source->queue);
else
wl_display_dispatch_pending (source->display);
source->pfd.revents = 0;
if (callback)
callback (data);
return TRUE;
}
static void
wayland_event_source_finalize (GSource * base)
{
WaylandEventSource *source = (WaylandEventSource *) base;
if (source->reading) {
wl_display_cancel_read (source->display);
}
source->reading = FALSE;
}
static GSourceFuncs wayland_event_source_funcs = {
wayland_event_source_prepare,
wayland_event_source_check,
wayland_event_source_dispatch,
wayland_event_source_finalize
};
GSource *
wayland_event_source_new (struct wl_display *display,
struct wl_event_queue *queue)
{
WaylandEventSource *source;
source = (WaylandEventSource *)
g_source_new (&wayland_event_source_funcs, sizeof (WaylandEventSource));
source->display = display;
source->queue = queue;
source->pfd.fd = wl_display_get_fd (display);
source->pfd.events = G_IO_IN | G_IO_ERR;
g_source_add_poll (&source->source, &source->pfd);
return &source->source;
}