Add a function for getting the current priority

src/common/utils.cpp

@@ -31,6 +31,16 @@ fs::path get_temporary_directory() {
     }
 }
 
+std::optional<int> get_scheduling_priority() {
+    sched_param current_params{};
+    if (sched_getparam(0, &current_params) == 0 &&
+        current_params.sched_priority > 0) {
+        return current_params.sched_priority;
+    } else {
+        return std::nullopt;
+    }
+}
+
 bool set_realtime_priority(bool sched_fifo) {
     sched_param params{.sched_priority = 5};
     return sched_setscheduler(0, sched_fifo ? SCHED_FIFO : SCHED_OTHER,

src/common/utils.h

@@ -36,6 +36,13 @@ overload(Ts...) -> overload<Ts...>;
  */
 boost::filesystem::path get_temporary_directory();
 
+/**
+ * Get the current thread's scheduling priority if the thread is using
+ * `SCHED_FIFO`. Returns a nullopt of the calling thread is not under realtime
+ * scheduling.
+ */
+std::optional<int> get_scheduling_priority();
+
 /**
  * Set the scheduling policy to `SCHED_FIFO` with priority 10 for this process.
  * We explicitly don't do this for wineserver itself since from my testing that