[Spice-devel] [RFC spice-streaming-agent 2/4] spice-streaming-agent: fully reset the capture loop on start/stop requests

[Snir Sheriber]

Hi,


On 8/6/19 6:34 PM, Kevin Pouget wrote:
> With this patch, spice-streaming-agent exits the frame-sending loop
> when START/STOP requests are received. This allows the recomputation
> of the most suitable capture/encoding plugin, that may have been
> updated with START/STOP message.
>
> Signed-off-by: Kevin Pouget <kpouget at redhat.com>
> ---
>   src/spice-streaming-agent.cpp | 19 +++++++++++++------
>   1 file changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/src/spice-streaming-agent.cpp b/src/spice-streaming-agent.cpp
> index 49f5dc4..d274b5f 100644
> --- a/src/spice-streaming-agent.cpp
> +++ b/src/spice-streaming-agent.cpp
> @@ -125,7 +125,8 @@ private:
>       static constexpr uint32_t max_device_address_len = 255;
>   };
>   
> -static bool streaming_requested = false;
> +static bool capture_in_progress = false;
> +static bool reset_requested = false;
>   static bool quit_requested = false;
>   static std::set<SpiceVideoCodecType> client_codecs;
>   
> @@ -167,11 +168,12 @@ static void read_command_from_device(StreamPort &stream_port)
>       }
>       case STREAM_TYPE_START_STOP: {
>           StartStopMessage msg = in_message.get_payload<StartStopMessage>();
> -        streaming_requested = msg.start_streaming;
> +        capture_in_progress = msg.start_streaming;
>           client_codecs = msg.client_codecs;
> +        reset_requested = true;
>   
>           syslog(LOG_INFO, "GOT START_STOP message -- request to %s streaming",
> -               streaming_requested ? "START" : "STOP");
> +               capture_in_progress ? "START" : "STOP");
>           return;
>       }}
>   
> @@ -233,20 +235,25 @@ do_capture(StreamPort &stream_port, FrameLog &frame_log, ConcreteAgent &agent)
>   {
>       unsigned int frame_count = 0;
>       while (!quit_requested) {
> -        while (!quit_requested && !streaming_requested) {
> +        while (!quit_requested && !capture_in_progress) {
>               read_command(stream_port, true);
>           }
>   
>           if (quit_requested) {
>               return;
>           }
> +        reset_requested = false;
>   
>           syslog(LOG_INFO, "streaming starts now");
>           uint64_t time_last = 0;
>   
>           std::unique_ptr<FrameCapture> capture(agent.GetBestFrameCapture(client_codecs));
>           if (!capture) {
> -            throw std::runtime_error("cannot find a suitable capture system");
> +            syslog(LOG_ERR, "Error cannot find a suitable capture system");
> +
> +            // wait until a new start/stop request arrives with a new list of codecs


Can you explain why you change it to a log message? in case of failure
how you'll get out of this loop? client codec types availability can change
in run time? or it can change only their preference?

Snir.

> +            capture_in_progress = false;
> +            continue;
>           }
>   
>           std::vector<DeviceDisplayInfo> display_info;
> @@ -275,7 +282,7 @@ do_capture(StreamPort &stream_port, FrameLog &frame_log, ConcreteAgent &agent)
>               syslog(LOG_ERR, "Empty device display info from the plugin");
>           }
>   
> -        while (!quit_requested && streaming_requested) {
> +        while (!quit_requested && !reset_requested && capture_in_progress) {
>               if (++frame_count % 100 == 0) {
>                   syslog(LOG_DEBUG, "SENT %d frames", frame_count);
>               }