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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2020 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
import Swift
@_implementationOnly import _SwiftConcurrencyShims
#if !SWIFT_STDLIB_TASK_TO_THREAD_MODEL_CONCURRENCY
@available(SwiftStdlib 5.7, *)
extension Task where Success == Never, Failure == Never {
@available(SwiftStdlib 5.7, *)
internal static func _sleep(
until seconds: Int64, _ nanoseconds: Int64,
tolerance: Duration?,
clock: _ClockID
) async throws {
// Create a token which will initially have the value "not started", which
// means the continuation has neither been created nor completed.
let token = UnsafeSleepStateToken()
do {
// Install a cancellation handler to resume the continuation by
// throwing CancellationError.
try await withTaskCancellationHandler {
let _: () = try await withUnsafeThrowingContinuation { continuation in
while true {
let state = token.load()
switch state {
case .notStarted:
// Try to swap in the continuation word.
let newState = SleepState.activeContinuation(continuation)
if !token.exchange(expected: state, desired: newState) {
// Keep trying!
continue
}
// Create a task that resumes the continuation normally if it
// finishes first. Enqueue it directly with the delay, so it fires
// when we're done sleeping.
let sleepTaskFlags = taskCreateFlags(
priority: nil, isChildTask: false, copyTaskLocals: false,
inheritContext: false, enqueueJob: false,
addPendingGroupTaskUnconditionally: false,
isDiscardingTask: false)
let (sleepTask, _) = Builtin.createAsyncTask(sleepTaskFlags) {
onSleepWake(token)
}
let toleranceSeconds: Int64
let toleranceNanoseconds: Int64
if let components = tolerance?.components {
toleranceSeconds = components.seconds
toleranceNanoseconds = components.attoseconds / 1_000_000_000
} else {
toleranceSeconds = 0
toleranceNanoseconds = -1
}
_enqueueJobGlobalWithDeadline(
seconds, nanoseconds,
toleranceSeconds, toleranceNanoseconds,
clock.rawValue, Builtin.convertTaskToJob(sleepTask))
return
case .activeContinuation, .finished:
fatalError("Impossible to have multiple active continuations")
case .cancelled:
fatalError("Impossible to have cancelled before we began")
case .cancelledBeforeStarted:
// Finish the continuation normally. We'll throw later, after
// we clean up.
continuation.resume()
return
}
}
}
} onCancel: {
onSleepCancel(token)
}
// Determine whether we got cancelled before we even started.
let cancelledBeforeStarted: Bool
switch token.load() {
case .notStarted, .activeContinuation, .cancelled:
fatalError("Invalid state for non-cancelled sleep task")
case .cancelledBeforeStarted:
cancelledBeforeStarted = true
case .finished:
cancelledBeforeStarted = false
}
// We got here without being cancelled, so deallocate the storage for
// the flag word and continuation.
token.deallocate()
// If we got cancelled before we even started, through the cancellation
// error now.
if cancelledBeforeStarted {
throw _Concurrency.CancellationError()
}
} catch {
// The task was cancelled; propagate the error. The "on wake" task is
// responsible for deallocating the flag word and continuation, if it's
// still running.
throw error
}
}
/// Suspends the current task until the given deadline within a tolerance.
///
/// If the task is canceled before the time ends, this function throws
/// `CancellationError`.
///
/// This function doesn't block the underlying thread.
///
/// try await Task.sleep(until: .now + .seconds(3))
///
@available(SwiftStdlib 5.7, *)
public static func sleep<C: Clock>(
until deadline: C.Instant,
tolerance: C.Instant.Duration? = nil,
clock: C = ContinuousClock()
) async throws {
try await clock.sleep(until: deadline, tolerance: tolerance)
}
/// Suspends the current task for the given duration.
///
/// If the task is cancelled before the time ends, this function throws
/// `CancellationError`.
///
/// This function doesn't block the underlying thread.
///
/// try await Task.sleep(for: .seconds(3))
///
@available(SwiftStdlib 5.7, *)
@_alwaysEmitIntoClient
public static func sleep<C: Clock>(
for duration: C.Instant.Duration,
tolerance: C.Instant.Duration? = nil,
clock: C = ContinuousClock()
) async throws {
try await clock.sleep(for: duration, tolerance: tolerance)
}
}
#else
@available(SwiftStdlib 5.7, *)
@available(*, unavailable, message: "Unavailable in task-to-thread concurrency model")
extension Task where Success == Never, Failure == Never {
@available(SwiftStdlib 5.7, *)
@available(*, unavailable, message: "Unavailable in task-to-thread concurrency model")
public static func sleep<C: Clock>(
until deadline: C.Instant,
tolerance: C.Instant.Duration? = nil,
clock: C = ContinuousClock()
) async throws {
fatalError("Unavailable in task-to-thread concurrency model")
}
@available(SwiftStdlib 5.7, *)
@available(*, unavailable, message: "Unavailable in task-to-thread concurrency model")
@_alwaysEmitIntoClient
public static func sleep<C: Clock>(
for duration: C.Instant.Duration,
tolerance: C.Instant.Duration? = nil,
clock: C = ContinuousClock()
) async throws {
fatalError("Unavailable in task-to-thread concurrency model")
}
}
#endif
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