Abstract definition of rt-scheduler policy

pthread-w32 does not support pthread_setschedparam() with
SCHED_FIFO and bails out. While pthread_create() simply ignores the policy
and sets the priority regadless.

This only affects ctrl-surface event-loops & AutomationWatch on Windows.

8 files changed, 23 insertions, 9 deletions

diff --git a/libs/ardour/automation_watch.cc b/libs/ardour/automation_watch.cc
index c949509d09..ad05f3ac69 100644
--- a/libs/ardour/automation_watch.cc
+++ b/libs/ardour/automation_watch.cc
@@ -186,7 +186,7 @@ AutomationWatch::timer ()
 void
 AutomationWatch::thread ()
 {
-	pbd_set_thread_priority (pthread_self(), SCHED_FIFO, -25);
+	pbd_set_thread_priority (pthread_self(), PBD_SCHED_FIFO, -25);
 	while (_run_thread) {
 		Glib::usleep ((gulong) floor (Config->get_automation_interval_msecs() * 1000));
 		timer ();
diff --git a/libs/backends/alsa/alsa_audiobackend.cc b/libs/backends/alsa/alsa_audiobackend.cc
index 9f42145314..525ff2e757 100644
--- a/libs/backends/alsa/alsa_audiobackend.cc
+++ b/libs/backends/alsa/alsa_audiobackend.cc
@@ -992,7 +992,7 @@ AlsaAudioBackend::_start (bool for_latency_measurement)
 	_run = true;
 	_port_change_flag = false;
 
-	if (pbd_realtime_pthread_create (SCHED_FIFO, -20, 100000,
+	if (pbd_realtime_pthread_create (PBD_SCHED_FIFO, -20, 100000,
 				&_main_thread, pthread_process, this))
 	{
 		if (pthread_create (&_main_thread, NULL, pthread_process, this))
@@ -1129,7 +1129,7 @@ AlsaAudioBackend::create_process_thread (boost::function<void()> func)
 
 	ThreadData* td = new ThreadData (this, func, stacksize);
 
-	if (pbd_realtime_pthread_create (SCHED_FIFO, -22, stacksize,
+	if (pbd_realtime_pthread_create (PBD_SCHED_FIFO, -22, stacksize,
 				&thread_id, alsa_process_thread, td)) {
 		pthread_attr_init (&attr);
 		pthread_attr_setstacksize (&attr, stacksize);
diff --git a/libs/backends/alsa/alsa_midi.cc b/libs/backends/alsa/alsa_midi.cc
index 348586ad20..d593f73def 100644
--- a/libs/backends/alsa/alsa_midi.cc
+++ b/libs/backends/alsa/alsa_midi.cc
@@ -72,7 +72,7 @@ static void * pthread_process (void *arg)
 int
 AlsaMidiIO::start ()
 {
-	if (pbd_realtime_pthread_create (SCHED_FIFO, -21, 100000,
+	if (pbd_realtime_pthread_create (PBD_SCHED_FIFO, -21, 100000,
 				&_main_thread, pthread_process, this))
 	{
 		if (pthread_create (&_main_thread, NULL, pthread_process, this)) {
diff --git a/libs/backends/coreaudio/coreaudio_backend.cc b/libs/backends/coreaudio/coreaudio_backend.cc
index 3e4a38e7a3..c4e11ef700 100644
--- a/libs/backends/coreaudio/coreaudio_backend.cc
+++ b/libs/backends/coreaudio/coreaudio_backend.cc
@@ -859,7 +859,7 @@ CoreAudioBackend::create_process_thread (boost::function<void()> func)
 
 	ThreadData* td = new ThreadData (this, func, stacksize);
 
-	if (pbd_realtime_pthread_create (SCHED_FIFO, -22, stacksize,
+	if (pbd_realtime_pthread_create (PBD_SCHED_FIFO, -22, stacksize,
 	                              &thread_id, coreaudio_process_thread, td)) {
 		pthread_attr_init (&attr);
 		pthread_attr_setstacksize (&attr, stacksize);
diff --git a/libs/backends/portaudio/portaudio_backend.cc b/libs/backends/portaudio/portaudio_backend.cc
index 3433ca3585..46e508fba7 100644
--- a/libs/backends/portaudio/portaudio_backend.cc
+++ b/libs/backends/portaudio/portaudio_backend.cc
@@ -787,7 +787,7 @@ PortAudioBackend::process_callback(const float* input,
 bool
 PortAudioBackend::start_blocking_process_thread ()
 {
-	if (pbd_realtime_pthread_create (SCHED_FIFO, -20, 100000,
+	if (pbd_realtime_pthread_create (PBD_SCHED_FIFO, -20, 100000,
 				&_main_blocking_thread, blocking_thread_func, this))
 	{
 		if (pthread_create (&_main_blocking_thread, NULL, blocking_thread_func, this))
@@ -1115,7 +1115,7 @@ PortAudioBackend::create_process_thread (boost::function<void()> func)
 
 	ThreadData* td = new ThreadData (this, func, stacksize);
 
-	if (pbd_realtime_pthread_create (SCHED_FIFO, -22, stacksize,
+	if (pbd_realtime_pthread_create (PBD_SCHED_FIFO, -22, stacksize,
 				&thread_id, portaudio_process_thread, td)) {
 		pthread_attr_init (&attr);
 		pthread_attr_setstacksize (&attr, stacksize);
diff --git a/libs/backends/portaudio/winmmemidi_output_device.cc b/libs/backends/portaudio/winmmemidi_output_device.cc
index 25201af67b..72b1494ac5 100644
--- a/libs/backends/portaudio/winmmemidi_output_device.cc
+++ b/libs/backends/portaudio/winmmemidi_output_device.cc
@@ -230,7 +230,7 @@ WinMMEMidiOutputDevice::start_midi_output_thread ()
 	size_t stacksize = 100000;
 
 	// TODO Use native threads
-	if (pbd_realtime_pthread_create (SCHED_FIFO, -21, stacksize,
+	if (pbd_realtime_pthread_create (PBD_SCHED_FIFO, -21, stacksize,
 				&m_output_thread_handle, midi_output_thread, this)) {
 		return false;
 	}
diff --git a/libs/pbd/pbd/base_ui.h b/libs/pbd/pbd/base_ui.h
index b8569718ae..4d490fea5c 100644
--- a/libs/pbd/pbd/base_ui.h
+++ b/libs/pbd/pbd/base_ui.h
@@ -32,6 +32,7 @@
 #include "pbd/libpbd_visibility.h"
 #include "pbd/crossthread.h"
 #include "pbd/event_loop.h"
+#include "pbd/pthread_utils.h"
 
 /** A BaseUI is an abstraction designed to be used with any "user
  * interface" (not necessarily graphical) that needs to wait on
@@ -91,7 +92,7 @@ class LIBPBD_API BaseUI : public sigc::trackable, public PBD::EventLoop
 
 	virtual void thread_init () {};
 
-	int set_thread_priority (const int policy = SCHED_FIFO, int priority = 0) const;
+	int set_thread_priority (const int policy = PBD_SCHED_FIFO, int priority = 0) const;
 
 	/** Called when there input ready on the request_channel
 	 */
diff --git a/libs/pbd/pbd/pthread_utils.h b/libs/pbd/pbd/pthread_utils.h
index 2ef442caa5..a1660eb073 100644
--- a/libs/pbd/pbd/pthread_utils.h
+++ b/libs/pbd/pbd/pthread_utils.h
@@ -67,4 +67,17 @@ namespace PBD {
 	LIBPBD_API extern PBD::Signal3<void,pthread_t,std::string,uint32_t> ThreadCreatedWithRequestSize;
 }
 
+/* pthread-w32 does not support realtime scheduling
+ * (well, windows, doesn't..) and only supports SetThreadPriority()
+ *
+ * pthread_setschedparam() returns ENOTSUP if the policy is not SCHED_OTHER.
+ *
+ * however, pthread_create() with attributes, ignores the policy and
+ * only sets the priority (when PTHREAD_EXPLICIT_SCHED is used).
+ */
+#ifdef PLATFORM_WINDOWS
+#define PBD_SCHED_FIFO SCHED_OTHER
+#else
+#define PBD_SCHED_FIFO SCHED_FIFO
+#endif
 #endif /* __pbd_pthread_utils__ */