[Spice-devel] [client v6 1/3] streaming: Report invalid streams to the server

[Francois Gouget]

The error is sent using the existing client stream report message where
the dropped frame count is maxed out while the received frame count is
zero. Servers that recognize it can then switch to sending regular
screen updates for that area so the client is not stuck with a frozen
area on the screen.
This can be useful in case the client is unable to decode the stream for
some reason like a bug in the GStreamer plugins, the decoder not liking
odd video dimensions, etc.

Signed-off-by: Francois Gouget <fgouget at codeweavers.com>
---

Used memset() and added a comment to indicate what's special about 
the report.
Moved sending the report to its own function which makes 
display_handle_stream_create() a bit clearer.


 src/channel-display.c | 69 +++++++++++++++++++++++++++++----------------------
 1 file changed, 39 insertions(+), 30 deletions(-)

diff --git a/src/channel-display.c b/src/channel-display.c
index 709b3d2..500ddfb 100644
--- a/src/channel-display.c
+++ b/src/channel-display.c
@@ -1077,6 +1077,40 @@ static void display_update_stream_region(display_stream *st)
     }
 }
 
+static void report_invalid_stream(SpiceChannel *channel, uint32_t id)
+{
+    if (spice_channel_test_capability(channel, SPICE_DISPLAY_CAP_STREAM_REPORT)) {
+        SpiceMsgcDisplayStreamReport report;
+        SpiceMsgOut *msg;
+
+        /* Send a special stream report (UINT_MAX dropped frames out of zero)
+         * to indicate there is no such stream.
+         */
+        spice_printerr("notify the server that stream %u does not exist", id);
+        memset(&report, 0, sizeof(report));
+        report.stream_id = id;
+        report.num_frames = 0;
+        report.num_drops = UINT_MAX;
+
+        msg = spice_msg_out_new(SPICE_CHANNEL(channel), SPICE_MSGC_DISPLAY_STREAM_REPORT);
+        msg->marshallers->msgc_display_stream_report(msg->marshaller, &report);
+        spice_msg_out_send(msg);
+    }
+}
+
+static display_stream *get_stream_by_id(SpiceChannel *channel, uint32_t id)
+{
+    SpiceDisplayChannelPrivate *c = SPICE_DISPLAY_CHANNEL(channel)->priv;
+
+    if (c != NULL && c->streams != NULL && id < c->nstreams &&
+        c->streams[id] != NULL) {
+        return c->streams[id];
+    }
+
+    report_invalid_stream(channel, id);
+    return NULL;
+}
+
 /* coroutine context */
 static void display_handle_stream_create(SpiceChannel *channel, SpiceMsgIn *in)
 {
@@ -1127,6 +1161,7 @@ static void display_handle_stream_create(SpiceChannel *channel, SpiceMsgIn *in)
     if (st->video_decoder == NULL) {
         spice_printerr("could not create a video decoder for codec %u", op->codec_type);
         destroy_stream(channel, op->id);
+        report_invalid_stream(channel, op->id);
     }
 }
 
@@ -1224,17 +1259,10 @@ void stream_display_frame(display_stream *st, SpiceMsgIn *frame_msg,
 static void display_update_stream_report(SpiceDisplayChannel *channel, uint32_t stream_id,
                                          uint32_t frame_time, int32_t latency)
 {
-    SpiceDisplayChannelPrivate *c = channel->priv;
-    display_stream *st;
+    display_stream *st = get_stream_by_id(SPICE_CHANNEL(channel), stream_id);
     guint64 now;
 
-    g_return_if_fail(c != NULL);
-    g_return_if_fail(c->streams != NULL);
-    g_return_if_fail(c->nstreams > stream_id);
-
-    st = channel->priv->streams[stream_id];
     g_return_if_fail(st != NULL);
-
     if (!st->report_is_active) {
         return;
     }
@@ -1347,15 +1375,10 @@ static void display_handle_stream_data(SpiceChannel *channel, SpiceMsgIn *in)
 {
     SpiceDisplayChannelPrivate *c = SPICE_DISPLAY_CHANNEL(channel)->priv;
     SpiceStreamDataHeader *op = spice_msg_in_parsed(in);
-    display_stream *st;
+    display_stream *st = get_stream_by_id(channel, op->id);
     guint32 mmtime;
     int32_t latency;
 
-    g_return_if_fail(c != NULL);
-    g_return_if_fail(c->streams != NULL);
-    g_return_if_fail(c->nstreams > op->id);
-
-    st =  c->streams[op->id];
     g_return_if_fail(st != NULL);
     mmtime = stream_get_time(st);
 
@@ -1415,17 +1438,10 @@ static void display_handle_stream_data(SpiceChannel *channel, SpiceMsgIn *in)
 /* coroutine context */
 static void display_handle_stream_clip(SpiceChannel *channel, SpiceMsgIn *in)
 {
-    SpiceDisplayChannelPrivate *c = SPICE_DISPLAY_CHANNEL(channel)->priv;
     SpiceMsgDisplayStreamClip *op = spice_msg_in_parsed(in);
-    display_stream *st;
-
-    g_return_if_fail(c != NULL);
-    g_return_if_fail(c->streams != NULL);
-    g_return_if_fail(c->nstreams > op->id);
+    display_stream *st = get_stream_by_id(channel, op->id);
 
-    st = c->streams[op->id];
     g_return_if_fail(st != NULL);
-
     if (st->msg_clip) {
         spice_msg_in_unref(st->msg_clip);
     }
@@ -1524,17 +1540,10 @@ static void display_handle_stream_destroy_all(SpiceChannel *channel, SpiceMsgIn
 /* coroutine context */
 static void display_handle_stream_activate_report(SpiceChannel *channel, SpiceMsgIn *in)
 {
-    SpiceDisplayChannelPrivate *c = SPICE_DISPLAY_CHANNEL(channel)->priv;
     SpiceMsgDisplayStreamActivateReport *op = spice_msg_in_parsed(in);
-    display_stream *st;
+    display_stream *st = get_stream_by_id(channel, op->stream_id);
 
-    g_return_if_fail(c != NULL);
-    g_return_if_fail(c->streams != NULL);
-    g_return_if_fail(c->nstreams > op->stream_id);
-
-    st = c->streams[op->stream_id];
     g_return_if_fail(st != NULL);
-
     st->report_is_active = TRUE;
     st->report_id = op->unique_id;
     st->report_max_window = op->max_window_size;
-- 
2.10.1