From 6d89488d64d44ed4b3283308a583b320300553c8 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Wed, 4 Jun 2014 00:56:20 +0200
Subject: [PATCH] ALSA backend: separate flags for is-running and
 should-be-running

---
 libs/backends/alsa/alsa_audiobackend.cc | 25 +++++++++++++++----------
 libs/backends/alsa/alsa_audiobackend.h  |  3 ++-
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/libs/backends/alsa/alsa_audiobackend.cc b/libs/backends/alsa/alsa_audiobackend.cc
index 68f54fbe46..e9dc8c339b 100644
--- a/libs/backends/alsa/alsa_audiobackend.cc
+++ b/libs/backends/alsa/alsa_audiobackend.cc
@@ -39,7 +39,8 @@ size_t AlsaAudioBackend::_max_buffer_size = 8192;
 AlsaAudioBackend::AlsaAudioBackend (AudioEngine& e, AudioBackendInfo& info)
 	: AudioBackend (e, info)
 	, _pcmi (0)
-	, _running (false)
+	, _run (false)
+	, _active (false)
 	, _freewheeling (false)
 	, _capture_device("")
 	, _playback_device("")
@@ -416,7 +417,7 @@ static void * pthread_process (void *arg)
 int
 AlsaAudioBackend::_start (bool for_latency_measurement)
 {
-	if (_running) {
+	if (_active || _run) {
 		PBD::error << _("AlsaAudioBackend: already active.") << endmsg;
 		return -1;
 	}
@@ -505,6 +506,7 @@ AlsaAudioBackend::_start (bool for_latency_measurement)
 
 	engine.buffer_size_change (_samples_per_period);
 	engine.reconnect_ports ();
+	_run = true;
 
 	if (_realtime_pthread_create (SCHED_FIFO, -20,
 				&_main_thread, pthread_process, this))
@@ -513,6 +515,7 @@ AlsaAudioBackend::_start (bool for_latency_measurement)
 		{
 			PBD::error << _("AlsaAudioBackend: failed to create process thread.") << endmsg;
 			delete _pcmi; _pcmi = 0;
+			_run = false;
 			return -1;
 		} else {
 			PBD::warning << _("AlsaAudioBackend: cannot acquire realtime permissions.") << endmsg;
@@ -520,11 +523,12 @@ AlsaAudioBackend::_start (bool for_latency_measurement)
 	}
 
 	int timeout = 5000;
-	while (!_running && --timeout > 0) { Glib::usleep (1000); }
+	while (!_active && --timeout > 0) { Glib::usleep (1000); }
 
-	if (timeout == 0 || !_running) {
+	if (timeout == 0 || !_active) {
 		PBD::error << _("AlsaAudioBackend: failed to start process thread.") << endmsg;
 		delete _pcmi; _pcmi = 0;
+		_run = false;
 		return -1;
 	}
 
@@ -535,11 +539,11 @@ int
 AlsaAudioBackend::stop ()
 {
 	void *status;
-	if (!_running) {
+	if (!_active) {
 		return 0;
 	}
 
-	_running = false;
+	_run = false;
 	if (pthread_join (_main_thread, &status)) {
 		PBD::error << _("AlsaAudioBackend: failed to terminate.") << endmsg;
 		return -1;
@@ -560,7 +564,7 @@ AlsaAudioBackend::stop ()
 
 	unregister_system_ports();
 	delete _pcmi; _pcmi = 0;
-	return 0;
+	return (_active == false) ? 0 : -1;
 }
 
 int
@@ -701,7 +705,7 @@ AlsaAudioBackend::my_name () const
 bool
 AlsaAudioBackend::available () const
 {
-	return true;
+	return _run && _active;
 }
 
 uint32_t
@@ -1280,7 +1284,7 @@ void *
 AlsaAudioBackend::main_process_thread ()
 {
 	AudioEngine::thread_init_callback (this);
-	_running = true;
+	_active = true;
 	_processed_samples = 0;
 
 	uint64_t clock1, clock2;
@@ -1288,7 +1292,7 @@ AlsaAudioBackend::main_process_thread ()
 	_pcmi->pcm_start ();
 	int no_proc_errors = 0;
 
-	while (_running) {
+	while (_run) {
 		long nr;
 		bool xrun = false;
 		if (!_freewheeling) {
@@ -1407,6 +1411,7 @@ AlsaAudioBackend::main_process_thread ()
 
 	}
 	_pcmi->pcm_stop ();
+	_active = false;
 	return 0;
 }
 
diff --git a/libs/backends/alsa/alsa_audiobackend.h b/libs/backends/alsa/alsa_audiobackend.h
index 7ff172efbb..cb9e50af10 100644
--- a/libs/backends/alsa/alsa_audiobackend.h
+++ b/libs/backends/alsa/alsa_audiobackend.h
@@ -280,7 +280,8 @@ class AlsaAudioBackend : public AudioBackend {
 		std::string _instance_name;
 		Alsa_pcmi *_pcmi;
 
-		bool  _running;
+		bool  _run; /* keep going or stop, ardour thread */
+		bool  _active; /* is running, process thread */
 		bool  _freewheeling;
 
 		void enumerate_midi_devices (std::vector<std::string> &) const;