[Spice-devel] [RFC PATCH spice-server v5 12/22] stream-channel: Support client connection/disconnection

[Frediano Ziglio]

When a new client is connected we must restart the stream so new
clients can receive correct data without having to wait for the
next full screen (which on idle screen could take ages).
On disconnection we should tell the guest to stop streaming
not wasting resources to stream not needed data.

Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
---
 server/stream-channel.c | 77 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)

diff --git a/server/stream-channel.c b/server/stream-channel.c
index 5baaf559..6e21660a 100644
--- a/server/stream-channel.c
+++ b/server/stream-channel.c
@@ -116,8 +116,32 @@ stream_channel_client_init(StreamChannelClient *client)
 }
 
 static void
+request_new_stream(StreamChannel *channel, StreamMsgStartStop *start)
+{
+    if (channel->start_cb) {
+        channel->start_cb(channel->start_opaque, start, channel);
+    }
+}
+
+static void
 stream_channel_client_on_disconnect(RedChannelClient *rcc)
 {
+    RedChannel *red_channel = red_channel_client_get_channel(rcc);
+
+    // if there are still some client connected keep streaming
+    // TODO, maybe would be worth sending new codecs if they are better
+    if (red_channel_is_connected(red_channel)) {
+        return;
+    }
+
+    StreamChannel *channel = STREAM_CHANNEL(red_channel);
+    channel->stream_id = -1;
+    channel->width = 0;
+    channel->height = 0;
+
+    // send stream stop to device
+    StreamMsgStartStop stop = { 0, };
+    request_new_stream(channel, &stop);
 }
 
 static StreamChannelClient*
@@ -253,6 +277,51 @@ stream_channel_new(RedsState *server, uint32_t id)
                         NULL);
 }
 
+// find common codecs supported by all clients
+static StreamMsgStartStop*
+stream_channel_get_supported_codecs(StreamChannel *channel)
+{
+    RedChannelClient *rcc;
+    int codec;
+
+    static const uint16_t codec2cap[] = {
+        0, // invalid
+        SPICE_DISPLAY_CAP_CODEC_MJPEG,
+        SPICE_DISPLAY_CAP_CODEC_VP8,
+        SPICE_DISPLAY_CAP_CODEC_H264,
+        SPICE_DISPLAY_CAP_CODEC_VP9,
+    };
+
+    bool supported[SPICE_N_ELEMENTS(codec2cap)];
+
+    for (codec = 0; codec < SPICE_N_ELEMENTS(codec2cap); ++codec) {
+        supported[codec] = true;
+    }
+
+    FOREACH_CLIENT(channel, rcc) {
+        for (codec = 1; codec < SPICE_N_ELEMENTS(codec2cap); ++codec) {
+            // if do not support codec delete from list
+            if (!red_channel_client_test_remote_cap(rcc, codec2cap[codec])) {
+                supported[codec] = false;
+            }
+        }
+    }
+
+    // surely mjpeg is supported
+    supported[SPICE_VIDEO_CODEC_TYPE_MJPEG] = true;
+
+    StreamMsgStartStop *start = spice_malloc0(sizeof(*start) + sizeof(start->codecs[0]) * 256);
+    int num = 0;
+    for (codec = 1; codec < SPICE_N_ELEMENTS(codec2cap); ++codec) {
+        if (supported[codec]) {
+            start->codecs[num++] = codec;
+        }
+    }
+    start->num_codecs = num;
+
+    return start;
+}
+
 static void
 stream_channel_connect(RedChannel *red_channel, RedClient *red_client, RedsStream *stream,
                        int migration, RedChannelCapabilities *caps)
@@ -265,6 +334,14 @@ stream_channel_connect(RedChannel *red_channel, RedClient *red_client, RedsStrea
     client = stream_channel_client_new(channel, red_client, stream, migration, caps);
     spice_return_if_fail(client != NULL);
 
+    // request new stream
+    StreamMsgStartStop* start = stream_channel_get_supported_codecs(channel);
+    // send in any case, even if list is not changed
+    // notify device about changes
+    request_new_stream(channel, start);
+    free(start);
+
+
     // TODO set capabilities like  SPICE_DISPLAY_CAP_MONITORS_CONFIG
     // see guest_set_client_capabilities
     RedChannelClient *rcc = RED_CHANNEL_CLIENT(client);
-- 
2.13.5