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// RUN: %target-run-simple-swift( -Xfrontend -disable-availability-checking %import-libdispatch -parse-as-library) | %FileCheck --dump-input=always %s
// REQUIRES: executable_test
// REQUIRES: concurrency
// REQUIRES: libdispatch
// rdar://76038845
// REQUIRES: concurrency_runtime
// UNSUPPORTED: back_deployment_runtime
import Dispatch
@available(SwiftStdlib 5.1, *)
@main struct Main {
static func main() async {
print("main priority: \(Task.currentPriority)") // CHECK: main priority: TaskPriority.medium
await test_detach()
await test_multiple_lo_indirectly_escalated()
}
}
@available(SwiftStdlib 5.1, *)
func test_detach() async {
let a1 = Task.currentPriority
print("a1: \(a1)") // CHECK: a1: TaskPriority.medium
// 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
// task.
await detach(priority: .userInitiated) {
let a2 = Task.currentPriority
print("a2: \(a2)") // CHECK: a2: TaskPriority.high
}.get()
let a3 = Task.currentPriority
print("a3: \(a3)") // CHECK: a3: TaskPriority.medium
}
@available(SwiftStdlib 5.1, *)
func test_multiple_lo_indirectly_escalated() async {
@Sendable
func loopUntil(priority: TaskPriority) async {
while (Task.currentPriority != priority) {
await Task.sleep(1_000_000_000)
}
}
let z = detach(priority: .background) {
await loopUntil(priority: .userInitiated)
}
let x = detach(priority: .background) {
_ = await z // waiting on `z`, but it won't complete since we're also background
await loopUntil(priority: .userInitiated)
}
// detach, don't wait
detach(priority: .userInitiated) {
await x // escalates x, which waits on z, so z also escalates
}
// since `_` awaited from userInitiated on `x` we:
// - boost `x` to `userInitiated`
// and then since `x` waits on `z`
// - `z` also gets boosted to `userInitiated`
// which "unlocks" it, allowing the 'default' `await z` to complete:
await x
await z
print("default done") // CHECK: default done
}
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