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

[Kevin Pouget <kpouget@xxxxxxxxxx>]

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@xxxxxxxxxx>
---
 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
+            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);
             }
-- 
2.21.0

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