gstreamer/gst-libs/gst/gl/wayland/wayland_event_source.c
Lucas Stach 7b8fc744f1 gl/wayland: fix wayland event source burning CPU
Commit c71dd72b "gl/wayland: fix glib mainloop integration" was overeager
in removing the poll result test from the check function. This caused
dispatch to be called even if no new events are available on the
Wayland connection, which in turn would wake up the glib mainloop,
causing effectively a tight loop without ever blocking on the poll.

Fixes #603
2019-07-26 08:48:05 +01:00

216 lines
5.7 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 (source->pfd.revents & G_IO_IN) {
if (wl_display_read_events (source->display) == 0)
return TRUE;
} else {
wl_display_cancel_read (source->display);
}
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;
}