OpenAL: Try to reset disconnected devices, fixes #209

OpenAL devices can disconnect, and with some luck they're back after
a few seconds. This especially seems to happen with Intels Windows GPU
driver and display-audio when switching the resolution or enabling
fullscreen, see #209
Now a disconnect is detected and we try to reset the device for 20
seconds, hoping it comes back. This needs at least openal-soft 1.17.0
to build and 1.20.0 or newer to actually work.

Also added missing stub functions in openal_stub.cpp (used by dedicated
server so it doesn't have to link libopenal)

neo/framework/Session.cpp

@@ -2520,12 +2520,18 @@ void idSessionLocal::UpdateScreen( bool outOfSequence ) {
 idSessionLocal::Frame
 ===============
 */
+extern bool CheckOpenALDeviceAndRecoverIfNeeded();
 void idSessionLocal::Frame() {
 
 	if ( com_asyncSound.GetInteger() == 0 ) {
 		soundSystem->AsyncUpdate( Sys_Milliseconds() );
 	}
 
+	// DG: periodically check if sound device is still there and try to reset it if not
+	//     (calling this from idSoundSystem::AsyncUpdate(), which runs in a separate thread
+	//      by default, causes a deadlock when calling idCommon->Warning())
+	CheckOpenALDeviceAndRecoverIfNeeded();
+
 	// Editors that completely take over the game
 	if ( com_editorActive && ( com_editors & ( EDITOR_RADIANT | EDITOR_GUI ) ) ) {
 		return;

neo/sound/snd_local.h

@@ -691,6 +691,11 @@ public:
 	ALuint					AllocOpenALSource( idSoundChannel *chan, bool looping, bool stereo );
 	void					FreeOpenALSource( ALuint handle );
 
+	// returns true if openalDevice is still available,
+	// otherwise it will try to recover the device and return false while it's gone
+	// (display audio sound devices sometimes disappear for a few seconds when switching resolution)
+	bool					CheckDeviceAndRecoverIfNeeded();
+
 	idSoundCache *			soundCache;
 
 	idSoundWorldLocal *		currentSoundWorld;	// the one to mix each async tic
@@ -747,6 +752,11 @@ public:
 							// mark available during initialization, or through an explicit test
 	static int				EFXAvailable;
 
+	// DG: for CheckDeviceAndRecoverIfNeeded()
+	LPALCRESETDEVICESOFT	alcResetDeviceSOFT; // needs ALC_SOFT_HRTF extension
+	int						resetRetryCount;
+	unsigned int			lastCheckTime;
+
 	static idCVar			s_noSound;
 	static idCVar			s_device;
 	static idCVar			s_quadraticFalloff;

neo/sound/snd_system.cpp

@@ -277,6 +277,17 @@ void SoundSystemRestart_f( const idCmdArgs &args ) {
 	soundSystem->SetMute( false );
 }
 
+// DG: make this function callable from idSessionLocal::Frame() without having to
+// change the public idSoundSystem interface - that would break mod DLL compat,
+// and this is not relevant for gamecode.
+bool CheckOpenALDeviceAndRecoverIfNeeded()
+{
+	if(soundSystemLocal.isInitialized)
+		return soundSystemLocal.CheckDeviceAndRecoverIfNeeded();
+
+	return true;
+}
+
 /*
 ===============
 idSoundSystemLocal::Init
@@ -313,6 +324,11 @@ void idSoundSystemLocal::Init() {
 
 	graph = NULL;
 
+	// DG: added these for CheckDeviceAndRecoverIfNeeded()
+	alcResetDeviceSOFT = NULL;
+	resetRetryCount = 0;
+	lastCheckTime = 0;
+
 	// DG: no point in initializing OpenAL if sound is disabled with s_noSound
 	if ( s_noSound.GetBool() ) {
 		common->Printf( "Sound disabled with s_noSound 1 !\n" );
@@ -385,6 +401,14 @@ void idSoundSystemLocal::Init() {
 		common->Printf( "OpenAL renderer: %s\n", alGetString(AL_RENDERER) );
 		common->Printf( "OpenAL version: %s\n", alGetString(AL_VERSION) );
 
+		// DG: extensions needed for CheckDeviceAndRecoverIfNeeded()
+		bool hasAlcExtDisconnect = alcIsExtensionPresent( openalDevice, "ALC_EXT_disconnect" ) != AL_FALSE;
+		bool hasAlcSoftHrtf = alcIsExtensionPresent( openalDevice, "ALC_SOFT_HRTF" ) != AL_FALSE;
+		if ( hasAlcExtDisconnect && hasAlcSoftHrtf ) {
+			common->Printf( "OpenAL: found extensions for resetting disconnected devices\n" );
+			alcResetDeviceSOFT = (LPALCRESETDEVICESOFT)alcGetProcAddress( openalDevice, "alcResetDeviceSOFT" );
+		}
+
 		// try to obtain EFX extensions
 		if (alcIsExtensionPresent(openalDevice, "ALC_EXT_EFX")) {
 			common->Printf( "OpenAL: found EFX extension\n" );
@@ -570,6 +594,63 @@ bool idSoundSystemLocal::ShutdownHW() {
 	return true;
 }
 
+
+/*
+===============
+idSoundSystemLocal::CheckDeviceAndRecoverIfNeeded
+
+ DG: returns true if openalDevice is still available,
+     otherwise it will try to recover the device and return false while it's gone
+     (display audio sound devices sometimes disappear for a few seconds when switching resolution)
+===============
+*/
+bool idSoundSystemLocal::CheckDeviceAndRecoverIfNeeded()
+{
+	static const int maxRetries = 20;
+
+	if ( alcResetDeviceSOFT == NULL ) {
+		return true; // we can't check or reset, just pretend everything is fine..
+	}
+
+	unsigned int curTime = Sys_Milliseconds();
+	if ( curTime - lastCheckTime >= 1000 ) // check once per second
+	{
+		lastCheckTime = curTime;
+
+		ALCint connected; // ALC_CONNECTED needs ALC_EXT_disconnect (we check for that in Init())
+		alcGetIntegerv( openalDevice, ALC_CONNECTED, 1, &connected );
+		if ( connected ) {
+			resetRetryCount = 0;
+			return true;
+		}
+
+		if ( resetRetryCount == 0 ) {
+			common->Warning( "OpenAL device disconnected! Will try to reconnect.." );
+			resetRetryCount = 1;
+		} else if ( resetRetryCount > maxRetries ) { // give up after 20 seconds
+			if ( resetRetryCount == maxRetries+1 ) {
+				common->Warning( "OpenAL device still disconnected! Giving up!" );
+				++resetRetryCount; // this makes sure the warning is only shown once
+
+				// TODO: can we shut down sound without things blowing up?
+				//       if we can, we could do that if we don't have alcResetDeviceSOFT but ALC_EXT_disconnect
+			}
+			return false;
+		}
+
+		if ( alcResetDeviceSOFT( openalDevice, NULL ) ) {
+			common->Printf( "OpenAL: resetting device succeeded!\n" );
+			resetRetryCount = 0;
+			return true;
+		}
+
+		++resetRetryCount;
+		return false;
+	}
+
+	return resetRetryCount == 0; // if it's 0, state on last check was ok
+}
+
 /*
 ===============
 idSoundSystemLocal::GetCurrent44kHzTime

neo/sys/stub/openal_stub.cpp

@@ -65,6 +65,17 @@ ALC_API ALCboolean ALC_APIENTRY alcIsExtensionPresent( ALCdevice *device, const
 	return AL_FALSE;
 }
 
+ALC_API void ALC_APIENTRY alcGetIntegerv(ALCdevice *device, ALCenum param, ALCsizei size, ALCint *values) {}
+
+ALC_API ALCenum ALC_APIENTRY alcGetError(ALCdevice *device) {
+	return ALC_NO_ERROR;
+}
+
+ALC_API void* ALC_APIENTRY alcGetProcAddress(ALCdevice *device, const ALCchar *funcname) {
+	return NULL;
+}
+
+
 AL_API void AL_APIENTRY alDeleteBuffers( ALsizei n, const ALuint* buffers ) { }
 
 AL_API ALboolean AL_APIENTRY alIsExtensionPresent( const ALchar* fname ) {