gstreamer/gst-libs/gst/gl/wayland/wayland_event_source.c
Lucas Stach c71dd72b21 gl/wayland: fix glib mainloop integration
Implement the prepare and check functions according to the
documentation by returning TRUE when events should be dispatched
via the dispatch function.

As wl_display_read_events never blocks we can call it unconditionally
without looking at the poll status.

This simplifies the implementation and gets rid of a race where the
mainloop could get blocked due to nobody actually reading the events
from the wayland connection.
2019-03-11 13:54:16 +01:00

212 lines
5.6 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 <gst/gst.h>
#include "wayland_event_source.h"
static void
sync_callback (void *data, struct wl_callback *callback, uint32_t serial)
{
gboolean *done = data;
GST_TRACE ("roundtrip done. callback:%p", callback);
*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.
* Otherwise, two prepare_read{_queue}()'s can be indicated for the same
* queue and dispatch{_queue}() may be called for different threads which
* will cause deadlocks as no guarantees for thread-safety are given when
* pumping the same queue from multiple threads.
* As a concrete example, if the wayland event source (below) for a @queue is
* running on a certain thread, then this function must only be called in that
* thread (with that @queue). */
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;
GST_TRACE ("roundtrip start for dpy %p and queue %p", display, queue);
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;
}
GST_TRACE ("create roundtrip callback %p", callback);
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);
GST_TRACE ("roundtrip done for dpy %p and queue %p. ret %i", display, queue,
ret);
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) {
if (wl_display_prepare_read_queue (source->display, source->queue) != 0)
return TRUE;
} else {
if (wl_display_prepare_read (source->display) != 0)
return TRUE;
}
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;
source->reading = FALSE;
if (wl_display_read_events (source->display) == 0)
return TRUE;
return FALSE;
}
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;
}