[Spice-devel] [RFC PATCH spice-server v2 11/19] stream-channel: Support client connection/disconnection

[Jonathon Jongsma]

On Wed, 2017-06-14 at 16:40 +0100, Frediano Ziglio wrote:
> On new client we must restart the stream so new clients

"On new client" -> "When a new client is connected"


> can receive correct data without having to wait next full

"wait" -> "wait for the"

> 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 | 78
> +++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 78 insertions(+)
> 
> diff --git a/server/stream-channel.c b/server/stream-channel.c
> index ae44f59..97128cb 100644
> --- a/server/stream-channel.c
> +++ b/server/stream-channel.c
> @@ -111,8 +111,32 @@ stream_channel_client_init(StreamChannelClient
> *client)
>  }
>  
>  static void
> +ask_new_stream(StreamChannel *channel, StreamMsgStartStop *start)
> +{
> +    if (channel->start_cb) {
> +        channel->start_cb(channel->start_opaque, start, channel);
> +    }
> +}

I think this could use a better name. Maybe start_stop_stream()? or
even request_new_stream()?

> +
> +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 start = { 0, };

Perhaps this variable would be better named "stop"

> +    ask_new_stream(channel, &start);
>  }
>  
>  static StreamChannelClient*
> @@ -247,6 +271,52 @@ stream_channel_new(RedsState *server)
>                          NULL);
>  }
>  
> +// find common codecs supported by all clients
> +static StreamMsgStartStop*
> +stream_channel_get_supported_codecs(StreamChannel *channel)
> +{
> +    GListIter iter;
> +    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, iter, 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;
> +}

I find this function name a little bit odd as well. It's really
allocating and returning a new start/stop message which is pre-filled
with the supported codecs. But the function name name doesn't mention
the message at all, only the codecs. I suppose it's fine as is, but I
think it might be more straightforward as something like:

stream_msg_start_stop_new_for_channel(StreamChannel*);

It's up to you.

> +
>  static void
>  stream_channel_connect(RedChannel *red_channel, RedClient
> *red_client, RedsStream *stream,
>                         int migration, RedChannelCapabilities *caps)
> @@ -259,6 +329,14 @@ 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);
>  
> +    // ask new stream

"ask" -> "request" or "ask for"

> +    StreamMsgStartStop* start =
> stream_channel_get_supported_codecs(channel);
> +    // send in any case, even if list is not changed
> +    // notify device about changes
> +    ask_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);