Guard calls into avrt.dll with a Mutex

mozilla · Mar 13, 2024 · 9ea70b5 · 9ea70b5
1 parent bcda8f3
commit 9ea70b5
Showing 1 changed file with 17 additions and 2 deletions.
diff --git a/src/rt_win.rs b/src/rt_win.rs
@@ -1,3 +1,7 @@
+use std::sync::Mutex;
+use std::sync::MutexGuard;
+use std::sync::OnceLock;
+
 use windows_sys::s;
 use windows_sys::Win32::Foundation::GetLastError;
 use windows_sys::Win32::Foundation::FALSE;
@@ -28,7 +32,10 @@ impl RtPriorityHandleInternal {
 pub fn demote_current_thread_from_real_time_internal(
     rt_priority_handle: RtPriorityHandleInternal,
 ) -> Result<(), AudioThreadPriorityError> {
-    let rv = unsafe { AvRevertMmThreadCharacteristics(rt_priority_handle.task_handle) };
+    let rv = {
+        let _guard = avrt_lock();
+        unsafe { AvRevertMmThreadCharacteristics(rt_priority_handle.task_handle) }
+    };
     if rv == FALSE {
         return Err(AudioThreadPriorityError::new(&format!(
             "Unable to restore the thread priority ({:?})",
@@ -50,7 +57,10 @@ pub fn promote_current_thread_to_real_time_internal(
 ) -> Result<RtPriorityHandleInternal, AudioThreadPriorityError> {
     let mut task_index = 0u32;
 
-    let handle = unsafe { AvSetMmThreadCharacteristicsA(s!("Audio"), &mut task_index) };
+    let handle = {
+        let _guard = avrt_lock();
+        unsafe { AvSetMmThreadCharacteristicsA(s!("Audio"), &mut task_index) }
+    };
     let handle = RtPriorityHandleInternal::new(task_index, handle);
 
     if handle.task_handle == 0 {
@@ -100,3 +110,8 @@ fn test_successful_api_use_3() {
     println!("result: {result:?}");
     assert!(result.is_ok());
 }
+
+fn avrt_lock() -> MutexGuard<'static, ()> {
+    static CELL: OnceLock<Mutex<()>> = OnceLock::new();
+    CELL.get_or_init(|| Mutex::new(())).lock().unwrap()
+}