Set device occupied when streamdev switches away LiveTV on the server, to

reduce the risk that the VDR main loop immediately switches back, resulting
in a black screen on the client (reported by hummel99)

Author: Frank Schmirler

CONTRIBUTORS

@@ -223,4 +223,5 @@ hivdr
   for suggesting to add the HTTP "Server" header
 
 hummel99
-  for helping to debug channel switch issues with priority > 0
+  for reporting and helping to debug channel switch issues with priority > 0
+  for reporting a race condition when switching the server's LiveTV device

HISTORY

@@ -1,7 +1,10 @@
 VDR Plugin 'streamdev' Revision History
 ---------------------------------------
 
-- Fixed channel switch issues with priority > 0
+- Set device occupied when streamdev switches away LiveTV on the server, to
+  reduce the risk that the VDR main loop immediately switches back, resulting
+  in a black screen on the client (reported by hummel99)
+- Fixed channel switch issues with priority > 0 (reported by hummel99)
 - Removed noisy debug messages
 - Fixed HTTP menu destruction
 - API change of VDR 2.1.2

server/connection.c

@@ -14,6 +14,11 @@
 #include <stdarg.h>
 #include <errno.h>
 
+// device occupied timeout to prevent VDR main loop to immediately switch back
+// when streamdev switched the live TV channel.
+// Note that there is still a gap between the GetDevice() and SetOccupied()
+// calls where the VDR main loop could strike
+#define STREAMDEVTUNETIMEOUT 5
 
 cServerConnection::cServerConnection(const char *Protocol, int Type):
 		cTBSocket(Type),
@@ -23,6 +28,7 @@ cServerConnection::cServerConnection(const char *Protocol, int Type):
 		m_ReadBytes(0),
 		m_WriteBytes(0),
 		m_WriteIndex(0),
+		m_OccupiedDev(NULL),
 		m_SwitchTo(NULL)
 {
 }
@@ -204,7 +210,7 @@ bool cServerConnection::UsedByLiveTV(cDevice *device)
 		(device->IsPrimaryDevice() && device->HasDecoder() && !device->Replaying());
 }
 
-cDevice *cServerConnection::GetDevice(const cChannel *Channel, int Priority) 
+cDevice *cServerConnection::SwitchDevice(const cChannel *Channel, int Priority) 
 {
 	// turn off the streams of this connection
 	Detach();
@@ -216,8 +222,22 @@ cDevice *cServerConnection::GetDevice(const cChannel *Channel, int Priority)
 		dsyslog("streamdev: GetDevice failed for channel %d (%s) at priority %d (PrimaryDevice=%d, ActualDevice=%d)", Channel->Number(), Channel->Name(), Priority, cDevice::PrimaryDevice()->CardIndex(), cDevice::ActualDevice()->CardIndex());
 	}
 	else if (!device->IsTunedToTransponder(Channel) && UsedByLiveTV(device)) {
-		// switched away live TV
-		m_SwitchTo = Channel;
+		// make sure VDR main loop doesn't switch back
+		device->SetOccupied(STREAMDEVTUNETIMEOUT);
+		if (device->SwitchChannel(Channel, false)) {
+			// switched away live TV
+			m_OccupiedDev = device;
+			m_SwitchTo = Channel;
+		}
+		else {
+			dsyslog("streamdev: SwitchChannel (live) failed for channel %d (%s) at priority %d (PrimaryDevice=%d, ActualDevice=%d, device=%d)", Channel->Number(), Channel->Name(), Priority, cDevice::PrimaryDevice()->CardIndex(), cDevice::ActualDevice()->CardIndex(), device->CardIndex());
+			device->SetOccupied(0);
+			device = NULL;
+		}
+	}
+	else if (!device->SwitchChannel(Channel, false)) {
+		dsyslog("streamdev: SwitchChannel failed for channel %d (%s) at priority %d (PrimaryDevice=%d, ActualDevice=%d, device=%d)", Channel->Number(), Channel->Name(), Priority, cDevice::PrimaryDevice()->CardIndex(), cDevice::ActualDevice()->CardIndex(), device->CardIndex());
+		device = NULL;
 	}
 	return device;
 }
@@ -240,6 +260,7 @@ void cServerConnection::MainThreadHook()
 			Channels.SwitchTo(m_SwitchTo->Number());
 			Skins.Message(mtInfo, tr("Streaming active"));
 		}
+		m_OccupiedDev->SetOccupied(0);
 		m_SwitchTo = NULL;
 	}
 }

server/connection.h

@@ -34,6 +34,8 @@ class cServerConnection: public cListObject, public cTBSocket
 	uint        m_WriteBytes;
 	uint        m_WriteIndex;
 
+	/* Set to occupied device when live TV was interrupted */
+	cDevice        *m_OccupiedDev;
 	/* Set to this connection's current channel when live TV was interrupted */
 	const cChannel *m_SwitchTo;
 
@@ -106,10 +108,8 @@ class cServerConnection: public cListObject, public cTBSocket
 	   channel. This call has no side effects. */
 	static cDevice *CheckDevice(const cChannel *Channel, int Priority, bool LiveView, const cDevice *AvoidDevice = NULL);
 
-	/* Will retrieve an unused device for transmitting data. Receivers have
-	   already been attached from the device if necessary. Use the returned
-	   cDevice in a following call to StartTransfer */
-	cDevice *GetDevice(const cChannel *Channel, int Priority);
+	/* Find a suitable device and tune it to the requested channel. */
+	cDevice *SwitchDevice(const cChannel *Channel, int Priority);
 
 	/* Test if a call to GetDevice would return a usable device. */
 	bool ProvidesChannel(const cChannel *Channel, int Priority);

server/connectionHTTP.c

@@ -177,9 +177,8 @@ bool cConnectionHTTP::ProcessRequest(void)
 		else if (m_Channel != NULL) {
 			cDevice *device = NULL;
 			if (ProvidesChannel(m_Channel, StreamdevServerSetup.HTTPPriority))
-				device = GetDevice(m_Channel, StreamdevServerSetup.HTTPPriority);
+				device = SwitchDevice(m_Channel, StreamdevServerSetup.HTTPPriority);
 			if (device != NULL) {
-				device->SwitchChannel(m_Channel, false);
 				cStreamdevLiveStreamer* liveStreamer = new cStreamdevLiveStreamer(StreamdevServerSetup.HTTPPriority, this);
 				m_Streamer = liveStreamer;
 				if (liveStreamer->SetChannel(m_Channel, m_StreamType, m_Apid[0] ? m_Apid : NULL, m_Dpid[0] ? m_Dpid : NULL)) {

server/connectionIGMP.c

@@ -44,9 +44,8 @@ void cConnectionIGMP::Welcome()
 {
 	cDevice *device = NULL;
 	if (ProvidesChannel(m_Channel, StreamdevServerSetup.IGMPPriority))
-		device = GetDevice(m_Channel, StreamdevServerSetup.IGMPPriority);
+		device = SwitchDevice(m_Channel, StreamdevServerSetup.IGMPPriority);
 	if (device != NULL) {
-		device->SwitchChannel(m_Channel, false);
 		m_LiveStreamer = new cStreamdevLiveStreamer(StreamdevServerSetup.IGMPPriority, this);
 		if (m_LiveStreamer->SetChannel(m_Channel, m_StreamType)) {
 			m_LiveStreamer->SetDevice(device);
@@ -61,7 +60,7 @@ void cConnectionIGMP::Welcome()
 		}
 	}
 	else
-		esyslog("streamdev-server IGMP: GetDevice failed");
+		esyslog("streamdev-server IGMP: SwitchDevice failed");
 }
 
 bool cConnectionIGMP::Close()

server/connectionVTP.c

@@ -1118,11 +1118,8 @@ bool cConnectionVTP::CmdTUNE(char *Opts)
 		if (!ProvidesChannel(chan, prio))
 			return Respond(560, "Channel not available (ProvidesChannel)");
 	}
-	if ((dev = GetDevice(chan, prio)) == NULL)
-		return Respond(560, "Channel not available (GetDevice)");
-
-	if (!dev->SwitchChannel(chan, false))
-		return Respond(560, "Channel not available (SwitchChannel)");
+	if ((dev = SwitchDevice(chan, prio)) == NULL)
+		return Respond(560, "Channel not available (SwitchDevice)");
 
 	delete m_LiveStreamer;
 	m_LiveStreamer = new cStreamdevLiveStreamer(prio, this);