[Spice-devel] [PATCH spice-gtk v2 2/2] channel-display: protect video streaming from temporarily unsynced mm_time (migration related)
Marc-André Lureau
marcandre.lureau at gmail.com
Tue Apr 30 18:24:40 PDT 2013
looks good, ack
On Tue, Apr 30, 2013 at 8:24 PM, Yonit Halperin <yhalperi at redhat.com> wrote:
> rhbz#951664
>
> When the src and dst servers have different mm-times, we can
> hit a case when for a short period of time the session mm-time and
> the video mm-time are not synced. If the video mm-time is much
> bigger than the session mm-time, the next stream rendering will be
> scheduled to (video-mm-time - session-mm-time), and even after
> the different mm-times are synced, the video won't be rendered
> till the rendering timeout that was scheduled based on a wrong mm-time,
> takes place.
> This patch protects from such cases. You can find more details in the
> code comments.
> ---
> gtk/channel-display.c | 108
> +++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 107 insertions(+), 1 deletion(-)
>
> diff --git a/gtk/channel-display.c b/gtk/channel-display.c
> index 9e03727..27ae0cb 100644
> --- a/gtk/channel-display.c
> +++ b/gtk/channel-display.c
> @@ -116,6 +116,8 @@ static gboolean display_stream_render(display_stream
> *st);
> static void spice_display_channel_reset(SpiceChannel *channel, gboolean
> migrating);
> static void spice_display_channel_reset_capabilities(SpiceChannel
> *channel);
> static void destroy_canvas(display_surface *surface);
> +static void _msg_in_unref_func(gpointer data, gpointer user_data);
> +static void display_session_mm_time_reset_cb(SpiceSession *session,
> gpointer data);
>
> /* ------------------------------------------------------------------ */
>
> @@ -157,6 +159,10 @@ static void spice_display_channel_constructed(GObject
> *object)
> g_return_if_fail(c->palettes != NULL);
>
> c->monitors = g_array_new(FALSE, TRUE,
> sizeof(SpiceDisplayMonitorConfig));
> + spice_g_signal_connect_object(s, "mm-time-reset",
> +
> G_CALLBACK(display_session_mm_time_reset_cb),
> + SPICE_CHANNEL(object), 0);
> +
>
> if (G_OBJECT_CLASS(spice_display_channel_parent_class)->constructed)
>
> G_OBJECT_CLASS(spice_display_channel_parent_class)->constructed(object);
> @@ -1089,6 +1095,8 @@ static gboolean
> display_stream_schedule(display_stream *st)
> guint32 time, d;
> SpiceStreamDataHeader *op;
> SpiceMsgIn *in;
> +
> + SPICE_DEBUG("%s", __FUNCTION__);
> if (st->timeout)
> return TRUE;
>
> @@ -1103,6 +1111,9 @@ static gboolean
> display_stream_schedule(display_stream *st)
> st->timeout = g_timeout_add(d,
> (GSourceFunc)display_stream_render, st);
> return TRUE;
> } else {
> + SPICE_DEBUG("%s: rendering too late by %u ms (ts: %u, mmtime:
> %u), dropping ",
> + __FUNCTION__, time - op->multi_media_time,
> + op->multi_media_time, time);
> in = g_queue_pop_head(st->msgq);
> spice_msg_in_unref(in);
> st->num_drops_on_playback++;
> @@ -1303,7 +1314,100 @@ static void
> display_update_stream_report(SpiceDisplayChannel *channel, uint32_t
> }
> }
>
> +static void display_stream_reset_rendering_timer(display_stream *st)
> +{
> + SPICE_DEBUG("%s", __FUNCTION__);
> + if (st->timeout != 0) {
> + g_source_remove(st->timeout);
> + st->timeout = 0;
> + }
> + while (!display_stream_schedule(st)) {
> + }
> +}
> +
> +/*
> + * Migration can occur between 2 spice-servers with different mm-times.
> + * Then, the following cases can happen after migration completes:
> + * (We refer to src/dst-time as the mm-times on the src/dst servers):
> + *
> + * (case 1) Frames with time ~= dst-time arrive to the client before the
> + * playback-channel updates the session's mm-time (i.e., the
> mm_time
> + * of the session is still based on the src-time).
> + * (a) If src-time < dst-time:
> + * display_stream_schedule schedules the next rendering to
> + * ~(dst-time - src-time) milliseconds from now.
> + * Since we assume monotonic mm_time, display_stream_schedule,
> + * returns immediately when a rendering timeout
> + * has already been set, and doesn't update the timeout,
> + * even after the mm_time is updated.
> + * When src-time << dst-time, a significant video frames loss
> will occur.
> + * (b) If src-time > dst-time
> + * Frames will be dropped till the mm-time will be updated.
> + * (case 2) mm-time is synced with dst-time, but frames that were in the
> command
> + * ring during migration still arrive (such frames hold src-time).
> + * (a) If src-time < dst-time
> + * The frames that hold src-time will be dropped, since their
> + * mm_time < session-mm_time. But all the new frames that are
> generated in
> + * the driver after migration, will be rendered appropriately.
> + * (b) If src-time > dst-time
> + * Similar consequences as in 1 (a)
> + * case 2 is less likely, since at takes at least 20 frames till the
> dst-server re-identifies
> + * the video stream and starts sending stream data
> + *
> + * display_session_mm_time_reset_cb handles case 1.a, and
> + * display_stream_test_frames_mm_time_reset handles case 2.b
> + */
> +
> +static void display_session_mm_time_reset_cb(SpiceSession *session,
> gpointer data)
> +{
> + SpiceChannel *channel = data;
> + SpiceDisplayChannelPrivate *c = SPICE_DISPLAY_CHANNEL(channel)->priv;
> + guint i;
> +
> + CHANNEL_DEBUG(channel, "%s", __FUNCTION__);
> +
> + for (i = 0; i < c->nstreams; i++) {
> + display_stream *st;
> +
> + if (c->streams[i] == NULL) {
> + continue;
> + }
> + SPICE_DEBUG("%s: stream-id %d", __FUNCTION__, i);
> + st = c->streams[i];
> + display_stream_reset_rendering_timer(st);
> + }
> +}
> +
> +static void display_stream_test_frames_mm_time_reset(display_stream *st,
> + SpiceMsgIn
> *new_frame_msg,
> + guint32 mm_time)
> +{
> + SpiceStreamDataHeader *tail_op, *new_op;
> + SpiceMsgIn *tail_msg;
> +
> + SPICE_DEBUG("%s", __FUNCTION__);
> + g_return_if_fail(new_frame_msg != NULL);
> + tail_msg = g_queue_peek_tail(st->msgq);
> + if (!tail_msg) {
> + return;
> + }
> + tail_op = spice_msg_in_parsed(tail_msg);
> + new_op = spice_msg_in_parsed(new_frame_msg);
> +
> + if (new_op->multi_media_time < tail_op->multi_media_time) {
> + SPICE_DEBUG("new-frame-time < tail-frame-time (%u < %u):"
> + " reseting stream, id %d",
> + new_op->multi_media_time,
> + tail_op->multi_media_time,
> + new_op->id);
> + g_queue_foreach(st->msgq, _msg_in_unref_func, NULL);
> + g_queue_clear(st->msgq);
> + display_stream_reset_rendering_timer(st);
> + }
> +}
> +
> #define STREAM_PLAYBACK_SYNC_DROP_SEQ_LEN_LIMIT 5
> +
> /* coroutine context */
> static void display_handle_stream_data(SpiceChannel *channel, SpiceMsgIn
> *in)
> {
> @@ -1349,8 +1453,10 @@ static void display_handle_stream_data(SpiceChannel
> *channel, SpiceMsgIn *in)
> } else {
> CHANNEL_DEBUG(channel, "video latency: %d", latency);
> spice_msg_in_ref(in);
> + display_stream_test_frames_mm_time_reset(st, in, mmtime);
> g_queue_push_tail(st->msgq, in);
> - display_stream_schedule(st);
> + while (!display_stream_schedule(st)) {
> + }
> if (st->cur_drops_seq_stats.len) {
> st->cur_drops_seq_stats.duration = op->multi_media_time -
>
> st->cur_drops_seq_stats.start_mm_time;
> --
> 1.8.1.4
>
> _______________________________________________
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> http://lists.freedesktop.org/mailman/listinfo/spice-devel
>
--
Marc-André Lureau
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