add special waker for priority events

tokio/src/io/ready.rs

@@ -176,7 +176,7 @@ impl Ready {
     /// ```
     #[cfg(any(target_os = "linux", target_os = "android"))]
     #[cfg_attr(docsrs, doc(cfg(any(target_os = "linux", target_os = "android"))))]
-    pub fn is_priority(self) -> bool {
+    pub fn is_priority_ready(self) -> bool {
         self.contains(Ready::PRIORITY)
     }
 
@@ -289,7 +289,7 @@ impl fmt::Debug for Ready {
                 .field("is_writable", &self.is_writable())
                 .field("is_read_closed", &self.is_read_closed())
                 .field("is_write_closed", &self.is_write_closed())
-                .field("is_priority", &self.is_priority())
+                .field("is_priority_ready", &self.is_priority_ready())
                 .finish()
         }
 

tokio/src/runtime/io/scheduled_io.rs

@@ -46,6 +46,9 @@ struct Waiters {
 
     /// Waker used for AsyncWrite.
     writer: Option<Waker>,
+
+    /// Waker used for Priority
+    priority: Option<Waker>,
 }
 
 cfg_io_readiness! {
@@ -238,6 +241,14 @@ impl ScheduledIo {
             }
         }
 
+        // check for AsyncWrite slot
+        #[cfg(any(target_os = "linux", target_os = "android"))]
+        if ready.is_priority_ready() {
+            if let Some(waker) = waiters.priority.take() {
+                wakers.push(waker);
+            }
+        }
+
         #[cfg(feature = "net")]
         'outer: loop {
             let mut iter = waiters.list.drain_filter(|w| ready.satisfies(w.interest));