Add MMCSS related code for raising thread priority on Windows

3 files changed, 212 insertions, 1 deletions

diff --git a/libs/backends/portaudio/mmcss.cc b/libs/backends/portaudio/mmcss.cc
new file mode 100644
index 0000000000..49551af339
--- /dev/null
+++ b/libs/backends/portaudio/mmcss.cc
@@ -0,0 +1,161 @@
+/*
+ * Copyright (C) 2015 Tim Mayberry <mojofunk@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "mmcss.h"
+
+#include "pbd/compose.h"
+
+#include "debug.h"
+
+typedef HANDLE (WINAPI* AvSetMmThreadCharacteristicsA_t)(LPCSTR TaskName,
+                                                         LPDWORD TaskIndex);
+
+typedef WINBOOL (WINAPI* AvRevertMmThreadCharacteristics_t)(HANDLE AvrtHandle);
+
+typedef WINBOOL (WINAPI* AvSetMmThreadPriority_t)(
+    HANDLE AvrtHandle, mmcss::AVRT_PRIORITY Priority);
+
+static HMODULE avrt_dll = NULL;
+
+static AvSetMmThreadCharacteristicsA_t AvSetMmThreadCharacteristicsA = NULL;
+static AvRevertMmThreadCharacteristics_t AvRevertMmThreadCharacteristics = NULL;
+static AvSetMmThreadPriority_t AvSetMmThreadPriority = NULL;
+
+
+namespace mmcss {
+
+bool
+initialize ()
+{
+	if (avrt_dll != NULL) return true;
+
+	avrt_dll = LoadLibraryA ("avrt.dll");
+
+	if (avrt_dll == NULL) {
+		DEBUG_THREADS ("Unable to load avrt.dll\n");
+		return false;
+	}
+	bool unload_dll = false;
+
+	AvSetMmThreadCharacteristicsA =
+	    (AvSetMmThreadCharacteristicsA_t)GetProcAddress (
+	        avrt_dll, "AvSetMmThreadCharacteristicsA");
+
+	if (AvSetMmThreadCharacteristicsA == NULL) {
+		DEBUG_THREADS ("Unable to resolve AvSetMmThreadCharacteristicsA\n");
+		unload_dll = true;
+	}
+
+	AvRevertMmThreadCharacteristics =
+	    (AvRevertMmThreadCharacteristics_t)GetProcAddress (
+	        avrt_dll, "AvRevertMmThreadCharacteristics");
+
+	if (AvRevertMmThreadCharacteristics == NULL) {
+		DEBUG_THREADS ("Unable to resolve AvRevertMmThreadCharacteristics\n");
+		unload_dll = true;
+	}
+
+	AvSetMmThreadPriority = (AvSetMmThreadPriority_t)GetProcAddress (
+	    avrt_dll, "AvSetMmThreadPriority");
+
+	if (AvSetMmThreadPriority == NULL) {
+		DEBUG_THREADS ("Unable to resolve AvSetMmThreadPriority\n");
+		unload_dll = true;
+	}
+
+	if (unload_dll) {
+		DEBUG_THREADS (
+		    "MMCSS Unable to resolve necessary symbols, unloading avrt.dll\n");
+		deinitialize ();
+	}
+
+	return true;
+}
+
+bool
+deinitialize ()
+{
+	if (avrt_dll == NULL) return true;
+
+	if (FreeLibrary (avrt_dll) == 0) {
+		DEBUG_THREADS ("Unable to unload avrt.dll\n");
+		return false;
+	}
+
+	avrt_dll = NULL;
+
+	AvSetMmThreadCharacteristicsA = NULL;
+	AvRevertMmThreadCharacteristics = NULL;
+	AvSetMmThreadPriority = NULL;
+
+	return true;
+}
+
+bool
+set_thread_characteristics (const std::string& task_name, HANDLE* task_handle)
+{
+	if (AvSetMmThreadCharacteristicsA == NULL) return false;
+
+	DWORD task_index_dummy = 0;
+
+	*task_handle = AvSetMmThreadCharacteristicsA(task_name.c_str(), &task_index_dummy);
+
+	if (*task_handle == 0) {
+		DEBUG_THREADS (string_compose ("Failed to set Thread Characteristics to %1\n",
+		                               task_name));
+		return false;
+	}
+
+	DEBUG_THREADS (
+	    string_compose ("Set thread characteristics to %1\n", task_name));
+
+	return true;
+}
+
+bool
+revert_thread_characteristics (HANDLE task_handle)
+{
+	if (AvRevertMmThreadCharacteristics == NULL) return false;
+
+	if (AvRevertMmThreadCharacteristics (task_handle) == 0) {
+		DEBUG_THREADS ("Failed to set revert thread characteristics\n");
+		return false;
+	}
+
+	DEBUG_THREADS ("Reverted thread characteristics\n");
+
+	return true;
+}
+
+bool
+set_thread_priority (HANDLE task_handle, AVRT_PRIORITY priority)
+{
+	if (AvSetMmThreadPriority == NULL) return false;
+
+	if (AvSetMmThreadPriority (task_handle, priority) == 0) {
+		DEBUG_THREADS (
+		    string_compose ("Failed to set thread priority %1\n", priority));
+		return false;
+	}
+
+	DEBUG_THREADS (string_compose ("Set thread priority to %1\n", priority));
+
+	return true;
+}
+
+} // namespace mmcss
diff --git a/libs/backends/portaudio/mmcss.h b/libs/backends/portaudio/mmcss.h
new file mode 100644
index 0000000000..deb9a417d3
--- /dev/null
+++ b/libs/backends/portaudio/mmcss.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2015 Tim Mayberry <mojofunk@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef MMCSS_H
+#define MMCSS_H
+
+#include <windows.h>
+
+#include <string>
+
+namespace mmcss {
+
+enum AVRT_PRIORITY {
+	AVRT_PRIORITY_VERYLOW = -2,
+	AVRT_PRIORITY_LOW,
+	AVRT_PRIORITY_NORMAL,
+	AVRT_PRIORITY_HIGH,
+	AVRT_PRIORITY_CRITICAL
+};
+
+bool initialize ();
+
+bool deinitialize ();
+
+bool set_thread_characteristics (const std::string& task_name, HANDLE *task_handle);
+
+bool revert_thread_characteristics (HANDLE task_handle);
+
+bool set_thread_priority (HANDLE, AVRT_PRIORITY);
+
+
+} // namespace mmcss
+
+#endif // MMCSS_H
diff --git a/libs/backends/portaudio/wscript b/libs/backends/portaudio/wscript
index 8bcfa5fa46..fcc0041a99 100644
--- a/libs/backends/portaudio/wscript
+++ b/libs/backends/portaudio/wscript
@@ -26,7 +26,8 @@ def build(bld):
                    'winmmemidi_input_device.cc',
                    'winmmemidi_output_device.cc',
                    'win_utils.cc',
-                   'midi_util.cc'
+                   'midi_util.cc',
+                   'mmcss.cc'
                  ]
     obj.includes = ['.']
     obj.name     = 'portaudio_backend'