Add a PBD API to set pthread priority

3 files changed, 68 insertions, 24 deletions

diff --git a/libs/pbd/base_ui.cc b/libs/pbd/base_ui.cc
index b04b755ec8..36c6216d45 100644
--- a/libs/pbd/base_ui.cc
+++ b/libs/pbd/base_ui.cc
@@ -82,30 +82,7 @@ BaseUI::new_request_type ()
 int
 BaseUI::set_thread_priority (const int policy, int priority) const
 {
-	struct sched_param param;
-	memset (&param, 0, sizeof (param));
-
-	/* POSIX requires a spread of at least 32 steps between min..max */
-	const int p_min = sched_get_priority_min (policy); // Linux: 1
-	const int p_max = sched_get_priority_max (policy); // Linux: 99
-
-	if (priority == 0) {
-		/* use default. XXX this should be relative to audio (JACK) thread,
-		 * internal backends use -20 (Audio), -21 (MIDI), -22 (compuation)
-		 */
-		priority = 7;
-	}
-
-	if (priority > 0) {
-		priority += p_min;
-	} else {
-		priority += p_max;
-	}
-	if (priority > p_max) priority = p_max;
-	if (priority < p_min) priority = p_min;
-	param.sched_priority = priority;
-
-	return pthread_setschedparam (pthread_self(), SCHED_FIFO, &param);
+	return pbd_set_thread_priority (pthread_self(), policy, priority);
 }
 
 void
diff --git a/libs/pbd/pbd/pthread_utils.h b/libs/pbd/pbd/pthread_utils.h
index 8f70fdac5b..2ef442caa5 100644
--- a/libs/pbd/pbd/pthread_utils.h
+++ b/libs/pbd/pbd/pthread_utils.h
@@ -54,6 +54,14 @@ LIBPBD_API void pthread_kill_all (int signum);
 LIBPBD_API const char* pthread_name ();
 LIBPBD_API void pthread_set_name (const char* name);
 
+LIBPBD_API int pbd_realtime_pthread_create (
+		const int policy, int priority, const size_t stacksize,
+		pthread_t *thread,
+		void *(*start_routine) (void *),
+		void *arg);
+
+LIBPBD_API int pbd_set_thread_priority (pthread_t, const int policy, int priority);
+
 namespace PBD {
 	LIBPBD_API extern void notify_event_loops_about_thread_creation (pthread_t, const std::string&, int requests = 256);
 	LIBPBD_API extern PBD::Signal3<void,pthread_t,std::string,uint32_t> ThreadCreatedWithRequestSize;
diff --git a/libs/pbd/pthread_utils.cc b/libs/pbd/pthread_utils.cc
index 5daa60ac42..c9b8f2980a 100644
--- a/libs/pbd/pthread_utils.cc
+++ b/libs/pbd/pthread_utils.cc
@@ -207,3 +207,62 @@ pthread_cancel_one (pthread_t thread)
 	pthread_cancel (thread);
 	pthread_mutex_unlock (&thread_map_lock);
 }
+
+int
+pbd_realtime_pthread_create (
+		const int policy, int priority, const size_t stacksize,
+		pthread_t *thread,
+		void *(*start_routine) (void *),
+		void *arg)
+{
+	int rv;
+
+	pthread_attr_t attr;
+	struct sched_param parm;
+
+	const int p_min = sched_get_priority_min (policy);
+	const int p_max = sched_get_priority_max (policy);
+	priority += p_max;
+	if (priority > p_max) priority = p_max;
+	if (priority < p_min) priority = p_min;
+	parm.sched_priority = priority;
+
+	pthread_attr_init (&attr);
+	pthread_attr_setschedpolicy (&attr, policy);
+	pthread_attr_setschedparam (&attr, &parm);
+	pthread_attr_setscope (&attr, PTHREAD_SCOPE_SYSTEM);
+	pthread_attr_setinheritsched (&attr, PTHREAD_EXPLICIT_SCHED);
+	pthread_attr_setstacksize (&attr, stacksize);
+	rv = pthread_create (thread, &attr, start_routine, arg);
+	pthread_attr_destroy (&attr);
+	return rv;
+}
+
+int
+pbd_set_thread_priority (pthread_t thread, const int policy, int priority)
+{
+	struct sched_param param;
+	memset (&param, 0, sizeof (param));
+
+	/* POSIX requires a spread of at least 32 steps between min..max */
+	const int p_min = sched_get_priority_min (policy); // Linux: 1
+	const int p_max = sched_get_priority_max (policy); // Linux: 99
+
+	if (priority == 0) {
+		/* use default. XXX this should be relative to audio (JACK) thread,
+		 * internal backends use -20 (Audio), -21 (MIDI), -22 (compuation)
+		 */
+		priority = 7; // BaseUI backwards compat.
+	}
+
+	if (priority > 0) {
+		priority += p_min;
+	} else {
+		priority += p_max;
+	}
+	if (priority > p_max) priority = p_max;
+	if (priority < p_min) priority = p_min;
+	param.sched_priority = priority;
+
+	return pthread_setschedparam (thread, SCHED_FIFO, &param);
+}