Implement process and thread priority adjustments (#691)

src/platform/common.h

@@ -306,6 +306,18 @@ std::vector<std::string> display_names(mem_type_e hwdevice_type);
 
 boost::process::child run_unprivileged(const std::string &cmd, boost::filesystem::path &working_dir, boost::process::environment &env, FILE *file, std::error_code &ec);
 
+enum class thread_priority_e : int {
+  low,
+  normal,
+  high,
+  critical
+};
+void adjust_thread_priority(thread_priority_e priority);
+
+// Allow OS-specific actions to be taken to prepare for streaming
+void streaming_will_start();
+void streaming_will_stop();
+
 input_t input();
 void move_mouse(input_t &input, int deltaX, int deltaY);
 void abs_mouse(input_t &input, const touch_port_t &touch_port, float x, float y);

src/platform/linux/misc.cpp

@@ -153,6 +153,18 @@ bp::child run_unprivileged(const std::string &cmd, boost::filesystem::path &work
   }
 }
 
+void adjust_thread_priority(thread_priority_e priority) {
+  // Unimplemented
+}
+
+void streaming_will_start() {
+  // Nothing to do
+}
+
+void streaming_will_stop() {
+  // Nothing to do
+}
+
 namespace source {
 enum source_e : std::size_t {
 #ifdef SUNSHINE_BUILD_CUDA

src/platform/macos/misc.cpp

@@ -131,6 +131,18 @@ bp::child run_unprivileged(const std::string &cmd, boost::filesystem::path &work
   }
 }
 
+void adjust_thread_priority(thread_priority_e priority) {
+  // Unimplemented
+}
+
+void streaming_will_start() {
+  // Nothing to do
+}
+
+void streaming_will_stop() {
+  // Nothing to do
+}
+
 } // namespace platf
 
 namespace dyn {

src/platform/windows/misc.cpp

@@ -13,9 +13,12 @@
 #include <winuser.h>
 #include <ws2tcpip.h>
 #include <userenv.h>
+#include <dwmapi.h>
+#include <timeapi.h>
 // clang-format on
 
 #include "src/main.h"
+#include "src/platform/common.h"
 #include "src/utility.h"
 
 namespace bp = boost::process;
@@ -470,4 +473,53 @@ bp::child run_unprivileged(const std::string &cmd, boost::filesystem::path &work
   }
 }
 
+void adjust_thread_priority(thread_priority_e priority) {
+  int win32_priority;
+
+  switch(priority) {
+  case thread_priority_e::low:
+    win32_priority = THREAD_PRIORITY_BELOW_NORMAL;
+    break;
+  case thread_priority_e::normal:
+    win32_priority = THREAD_PRIORITY_NORMAL;
+    break;
+  case thread_priority_e::high:
+    win32_priority = THREAD_PRIORITY_ABOVE_NORMAL;
+    break;
+  case thread_priority_e::critical:
+    win32_priority = THREAD_PRIORITY_HIGHEST;
+    break;
+  default:
+    BOOST_LOG(error) << "Unknown thread priority: "sv << (int)priority;
+    return;
+  }
+
+  if(!SetThreadPriority(GetCurrentThread(), win32_priority)) {
+    auto winerr = GetLastError();
+    BOOST_LOG(warning) << "Unable to set thread priority to "sv << win32_priority << ": "sv << winerr;
+  }
+}
+
+void streaming_will_start() {
+  // Enable MMCSS scheduling for DWM
+  DwmEnableMMCSS(true);
+
+  // Reduce timer period to 1ms
+  timeBeginPeriod(1);
+
+  // Promote ourselves to high priority class
+  SetPriorityClass(GetCurrentProcess(), HIGH_PRIORITY_CLASS);
+}
+
+void streaming_will_stop() {
+  // Demote ourselves back to normal priority class
+  SetPriorityClass(GetCurrentProcess(), NORMAL_PRIORITY_CLASS);
+
+  // End our 1ms timer request
+  timeEndPeriod(1);
+
+  // Disable MMCSS scheduling for DWM
+  DwmEnableMMCSS(false);
+}
+
 } // namespace platf