Workaround the actor runtimes unwillingness to deal with priorities properly

rdar://79378627

Author: aschwaighofer

stdlib/public/Concurrency/Task.swift

@@ -257,7 +257,7 @@ extension Task where Success == Never, Failure == Never {
       }
 
       // Otherwise, query the system.
-      return TaskPriority(rawValue: UInt8(_getCurrentThreadPriority()))
+      return TaskPriority(rawValue: UInt8(0))
     }
   }
 }
@@ -266,10 +266,6 @@ extension Task where Success == Never, Failure == Never {
 extension TaskPriority {
   /// Downgrade user-interactive to user-initiated.
   var _downgradeUserInteractive: TaskPriority {
-    if self == .userInteractive {
-      return .userInitiated
-    }
-
     return self
   }
 }
@@ -519,7 +515,7 @@ extension Task where Failure == Never {
     // Set up the job flags for a new task.
     var flags = JobFlags()
     flags.kind = .task
-    flags.priority = priority ?? .default
+    flags.priority = priority ?? .unspecified
     flags.isFuture = true
 
     // Create the asynchronous task future.
@@ -574,7 +570,7 @@ extension Task where Failure == Error {
     // Set up the job flags for a new task.
     var flags = JobFlags()
     flags.kind = .task
-    flags.priority = priority ?? .default
+    flags.priority = priority ?? .unspecified
     flags.isFuture = true
 
     // Create the asynchronous task future.
@@ -694,7 +690,7 @@ public struct UnsafeCurrentTask {
   /// - SeeAlso: `TaskPriority`
   /// - SeeAlso: `Task.currentPriority`
   public var priority: TaskPriority {
-    getJobFlags(_task).priority ?? .default
+    getJobFlags(_task).priority ?? .unspecified
   }
 }
 

test/Concurrency/Runtime/actor_detach.swift

@@ -0,0 +1,48 @@
+// RUN: %target-run-simple-swift(-Xfrontend -enable-experimental-concurrency) | %FileCheck %s
+
+// REQUIRES: executable_test
+// REQUIRES: concurrency
+
+import Foundation
+
+@available(SwiftStdlib 5.5, *)
+actor Manager {
+    static var shared = Manager()
+
+    func manage() async -> Int {
+        print("manage")
+        return 0
+    }
+
+    func other() async -> Int{
+        print("other")
+        return 0
+    }
+}
+
+
+@available(SwiftStdlib 5.5, *)
+func test() {
+    detach {
+        let x = await Manager.shared.manage()
+        print(x)
+    }
+    detach {
+        let x = await Manager.shared.other()
+        print(x)
+    }
+}
+
+if #available(SwiftStdlib 5.5, *) {
+ test()
+ sleep(30)
+} else {
+ print("manage")
+ print("0")
+ print("other")
+ print("0")
+}
+// CHECK-DAG: manage
+// CHECK-DAG: 0
+// CHECK-DAG: other
+// CHECK-DAG: 0

test/Concurrency/Runtime/async_task_priority_current.swift

@@ -13,7 +13,7 @@ import Dispatch
 @available(SwiftStdlib 5.5, *)
 func test_detach() async {
   let a1 = Task.currentPriority
-  print("a1: \(a1)") // CHECK: TaskPriority(rawValue: 21)
+  print("a1: \(a1)") // CHECK: TaskPriority(rawValue: 0)
 
   // Note: remember to detach using a higher priority, otherwise a lower one
   // might be escalated by the get() and we could see `default` in the detached
@@ -24,7 +24,7 @@ func test_detach() async {
   }.get()
 
   let a3 = Task.currentPriority
-  print("a3: \(a3)") // CHECK: a3: TaskPriority(rawValue: 21)
+  print("a3: \(a3)") // CHECK: a3: TaskPriority(rawValue: 0)
 }
 
 @available(SwiftStdlib 5.5, *)