src/swift/Queue.swift - third_party/swift-corelibs-libdispatch - Git at Google

 //===----------------------------------------------------------------------===//
 //
 // This source file is part of the Swift.org open source project
 //
 // Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See http://swift.org/LICENSE.txt for license information
 // See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 //
 //===----------------------------------------------------------------------===//

 // dispatch/queue.h

 import CDispatch
 import _SwiftDispatchOverlayShims

 public final class DispatchSpecificKey<T> {
 	public init() {}
 }

 internal class _DispatchSpecificValue<T> {
 	internal let value: T
 	internal init(value: T) { self.value = value }
 }

 public extension DispatchQueue {
 	public struct Attributes : OptionSet {
 		public let rawValue: UInt64
 		public init(rawValue: UInt64) { self.rawValue = rawValue }

 		public static let concurrent = Attributes(rawValue: 1<<1)

 		@available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *)
 		public static let initiallyInactive = Attributes(rawValue: 1<<2)

 		fileprivate func _attr() -> dispatch_queue_attr_t? {
 			var attr: dispatch_queue_attr_t? = nil

 			if self.contains(.concurrent) {
 				attr = _swift_dispatch_queue_concurrent()
 			}
 			if #available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *) {
 				if self.contains(.initiallyInactive) {
 					attr = CDispatch.dispatch_queue_attr_make_initially_inactive(attr)
 				}
 			}
 			return attr
 		}
 	}

 	public enum GlobalQueuePriority {
 		@available(OSX, deprecated: 10.10, message: "Use qos attributes instead")
 		@available(*, deprecated: 8.0, message: "Use qos attributes instead")
 		case high

 		@available(OSX, deprecated: 10.10, message: "Use qos attributes instead")
 		@available(*, deprecated: 8.0, message: "Use qos attributes instead")
 		case `default`

 		@available(OSX, deprecated: 10.10, message: "Use qos attributes instead")
 		@available(*, deprecated: 8.0, message: "Use qos attributes instead")
 		case low

 		@available(OSX, deprecated: 10.10, message: "Use qos attributes instead")
 		@available(*, deprecated: 8.0, message: "Use qos attributes instead")
 		case background

 		internal var _translatedValue: Int {
 			switch self {
 			case .high: return 2 // DISPATCH_QUEUE_PRIORITY_HIGH
 			case .default: return 0 // DISPATCH_QUEUE_PRIORITY_DEFAULT
 			case .low: return -2 // DISPATCH_QUEUE_PRIORITY_LOW
 			case .background: return Int(Int16.min) // DISPATCH_QUEUE_PRIORITY_BACKGROUND
 			}
 		}
 	}

 	public enum AutoreleaseFrequency {
 		case inherit

 		@available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *)
 		case workItem

 		@available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *)
 		case never

 		internal func _attr(attr: dispatch_queue_attr_t?) -> dispatch_queue_attr_t? {
 			if #available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *) {
 				switch self {
 				case .inherit:
 					// DISPATCH_AUTORELEASE_FREQUENCY_INHERIT
 					return CDispatch.dispatch_queue_attr_make_with_autorelease_frequency(attr, dispatch_autorelease_frequency_t(0))
 				case .workItem:
 					// DISPATCH_AUTORELEASE_FREQUENCY_WORK_ITEM
 					return CDispatch.dispatch_queue_attr_make_with_autorelease_frequency(attr, dispatch_autorelease_frequency_t(1))
 				case .never:
 					// DISPATCH_AUTORELEASE_FREQUENCY_NEVER
 					return CDispatch.dispatch_queue_attr_make_with_autorelease_frequency(attr, dispatch_autorelease_frequency_t(2))
 				}
 			} else {
 				return attr
 			}
 		}
 	}

 	public class func concurrentPerform(iterations: Int, execute work: (Int) -> Void) {
 		_swift_dispatch_apply_current(iterations, work)
 	}

 	public class var main: DispatchQueue {
 		return DispatchQueue(queue: _swift_dispatch_get_main_queue())
 	}

 	@available(OSX, deprecated: 10.10, message: "")
 	@available(*, deprecated: 8.0, message: "")
 	public class func global(priority: GlobalQueuePriority) -> DispatchQueue {
 		return DispatchQueue(queue: CDispatch.dispatch_get_global_queue(priority._translatedValue, 0))
 	}

 	@available(OSX 10.10, iOS 8.0, *)
 	public class func global(qos: DispatchQoS.QoSClass = .default) -> DispatchQueue {
 		return DispatchQueue(queue: CDispatch.dispatch_get_global_queue(Int(qos.rawValue.rawValue), 0))
 	}

 	public class func getSpecific<T>(key: DispatchSpecificKey<T>) -> T? {
 		let k = Unmanaged.passUnretained(key).toOpaque()
 		if let p = CDispatch.dispatch_get_specific(k) {
 			let v = Unmanaged<_DispatchSpecificValue<T>>
 				.fromOpaque(p)
 				.takeUnretainedValue()
 			return v.value
 		}
 		return nil
 	}

 	public convenience init(
 		label: String,
 		qos: DispatchQoS = .unspecified,
 		attributes: Attributes = [],
 		autoreleaseFrequency: AutoreleaseFrequency = .inherit,
 		target: DispatchQueue? = nil)
 	{
 		var attr = attributes._attr()
 		if autoreleaseFrequency != .inherit {
 			attr = autoreleaseFrequency._attr(attr: attr)
 		}
 		if #available(OSX 10.10, iOS 8.0, *), qos != .unspecified {
 			attr = CDispatch.dispatch_queue_attr_make_with_qos_class(attr, qos.qosClass.rawValue.rawValue, Int32(qos.relativePriority))
 		}

 		if #available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *) {
 			self.init(__label: label, attr: attr, queue: target)
 		} else {
 			self.init(__label: label, attr: attr)
 			if let tq = target { self.setTarget(queue: tq) }
 		}
 	}

 	public var label: String {
 		return String(validatingUTF8: dispatch_queue_get_label(self.__wrapped))!
 	}

 	@available(OSX 10.10, iOS 8.0, *)
 	public func sync(execute workItem: DispatchWorkItem) {
 		CDispatch.dispatch_sync(self.__wrapped, workItem._block)
 	}

 	@available(OSX 10.10, iOS 8.0, *)
 	public func async(execute workItem: DispatchWorkItem) {
 		CDispatch.dispatch_async(self.__wrapped, workItem._block)
 	}

 	@available(OSX 10.10, iOS 8.0, *)
 	public func async(group: DispatchGroup, execute workItem: DispatchWorkItem) {
 		CDispatch.dispatch_group_async(group.__wrapped, self.__wrapped, workItem._block)
 	}

 	public func async(
 		group: DispatchGroup? = nil,
 		qos: DispatchQoS = .unspecified,
 		flags: DispatchWorkItemFlags = [],
 		execute work: @escaping @convention(block) () -> Void)
 	{
 		if group == nil && qos == .unspecified {
 			// Fast-path route for the most common API usage
 			if flags.isEmpty {
 				CDispatch.dispatch_async(self.__wrapped, work)
 				return
 			} else if flags == .barrier {
 				CDispatch.dispatch_barrier_async(self.__wrapped, work)
 				return
 			}
 		}

 		var block: @convention(block) () -> Void = work
 		if #available(OSX 10.10, iOS 8.0, *), (qos != .unspecified || !flags.isEmpty) {
 			let workItem = DispatchWorkItem(qos: qos, flags: flags, block: work)
 			block = workItem._block
 		}

 		if let g = group {
 			CDispatch.dispatch_group_async(g.__wrapped, self.__wrapped, block)
 		} else {
 			CDispatch.dispatch_async(self.__wrapped, block)
 		}
 	}

 	private func _syncBarrier(block: () -> ()) {
 		CDispatch.dispatch_barrier_sync(self.__wrapped, block)
 	}

 	private func _syncHelper<T>(
 		fn: (() -> ()) -> (),
 		execute work: () throws -> T,
 		rescue: ((Swift.Error) throws -> (T))) rethrows -> T
 	{
 		var result: T?
 		var error: Swift.Error?
 		withoutActuallyEscaping(work) { _work in
 			fn {
 				do {
 					result = try _work()
 				} catch let e {
 					error = e
 				}
 			}
 		}
 		if let e = error {
 			return try rescue(e)
 		} else {
 			return result!
 		}
 	}

 	@available(OSX 10.10, iOS 8.0, *)
 	private func _syncHelper<T>(
 		fn: (DispatchWorkItem) -> (),
 		flags: DispatchWorkItemFlags,
 		execute work: () throws -> T,
 		rescue: @escaping ((Swift.Error) throws -> (T))) rethrows -> T
 	{
 		var result: T?
 		var error: Swift.Error?
 		let workItem = DispatchWorkItem(flags: flags, noescapeBlock: {
 			do {
 				result = try work()
 			} catch let e {
 				error = e
 			}
 		})
 		fn(workItem)
 		if let e = error {
 			return try rescue(e)
 		} else {
 			return result!
 		}
 	}

 	public func sync<T>(execute work: () throws -> T) rethrows -> T {
 		return try self._syncHelper(fn: sync, execute: work, rescue: { throw $0 })
 	}

 	public func sync<T>(flags: DispatchWorkItemFlags, execute work: () throws -> T) rethrows -> T {
 		if flags == .barrier {
 			return try self._syncHelper(fn: _syncBarrier, execute: work, rescue: { throw $0 })
 		} else if #available(OSX 10.10, iOS 8.0, *), !flags.isEmpty {
 			return try self._syncHelper(fn: sync, flags: flags, execute: work, rescue: { throw $0 })
 		} else {
 			return try self._syncHelper(fn: sync, execute: work, rescue: { throw $0 })
 		}
 	}

 	public func asyncAfter(
 		deadline: DispatchTime,
 		qos: DispatchQoS = .unspecified,
 		flags: DispatchWorkItemFlags = [],
 		execute work: @escaping @convention(block) () -> Void)
 	{
 		if #available(OSX 10.10, iOS 8.0, *), qos != .unspecified || !flags.isEmpty {
 			let item = DispatchWorkItem(qos: qos, flags: flags, block: work)
 			CDispatch.dispatch_after(deadline.rawValue, self.__wrapped, item._block)
 		} else {
 			CDispatch.dispatch_after(deadline.rawValue, self.__wrapped, work)
 		}
 	}

 	public func asyncAfter(
 		wallDeadline: DispatchWallTime,
 		qos: DispatchQoS = .unspecified,
 		flags: DispatchWorkItemFlags = [],
 		execute work: @escaping @convention(block) () -> Void)
 	{
 		if #available(OSX 10.10, iOS 8.0, *), qos != .unspecified || !flags.isEmpty {
 			let item = DispatchWorkItem(qos: qos, flags: flags, block: work)
 			CDispatch.dispatch_after(wallDeadline.rawValue, self.__wrapped, item._block)
 		} else {
 			CDispatch.dispatch_after(wallDeadline.rawValue, self.__wrapped, work)
 		}
 	}

 	@available(OSX 10.10, iOS 8.0, *)
 	public func asyncAfter(deadline: DispatchTime, execute: DispatchWorkItem) {
 		CDispatch.dispatch_after(deadline.rawValue, self.__wrapped, execute._block)
 	}

 	@available(OSX 10.10, iOS 8.0, *)
 	public func asyncAfter(wallDeadline: DispatchWallTime, execute: DispatchWorkItem) {
 		CDispatch.dispatch_after(wallDeadline.rawValue, self.__wrapped, execute._block)
 	}

 	@available(OSX 10.10, iOS 8.0, *)
 	public var qos: DispatchQoS {
 		var relPri: Int32 = 0
 		let cls = DispatchQoS.QoSClass(rawValue: _OSQoSClass(qosClass: dispatch_queue_get_qos_class(self.__wrapped, &relPri))!)!
 		return DispatchQoS(qosClass: cls, relativePriority: Int(relPri))
 	}

 	public func getSpecific<T>(key: DispatchSpecificKey<T>) -> T? {
 		let k = Unmanaged.passUnretained(key).toOpaque()
 		if let p = dispatch_queue_get_specific(self.__wrapped, k) {
 			let v = Unmanaged<_DispatchSpecificValue<T>>
 				.fromOpaque(p)
 				.takeUnretainedValue()
 			return v.value
 		}
 		return nil
 	}

 	public func setSpecific<T>(key: DispatchSpecificKey<T>, value: T?) {
 		let k = Unmanaged.passUnretained(key).toOpaque()
 		let v = value.flatMap { _DispatchSpecificValue(value: $0) }
 		let p = v.flatMap { Unmanaged.passRetained($0).toOpaque() }
 		dispatch_queue_set_specific(self.__wrapped, k, p, _destructDispatchSpecificValue)
 	}

 	#if os(Android)
 	public static func setThreadDetachCallback(_ cb: @escaping @convention(c) () -> Void) {
 		_dispatch_install_thread_detach_callback(cb)
 	}
 	#endif
 }

 private func _destructDispatchSpecificValue(ptr: UnsafeMutableRawPointer?) {
 	if let p = ptr {
 		Unmanaged<AnyObject>.fromOpaque(p).release()
 	}
 }
	//===----------------------------------------------------------------------===//
	//
	// This source file is part of the Swift.org open source project
	//
	// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
	// Licensed under Apache License v2.0 with Runtime Library Exception
	//
	// See http://swift.org/LICENSE.txt for license information
	// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
	//
	//===----------------------------------------------------------------------===//

	// dispatch/queue.h

	import CDispatch
	import _SwiftDispatchOverlayShims

	public final class DispatchSpecificKey<T> {
	public init() {}
	}

	internal class _DispatchSpecificValue<T> {
	internal let value: T
	internal init(value: T) { self.value = value }
	}

	public extension DispatchQueue {
	public struct Attributes : OptionSet {
	public let rawValue: UInt64
	public init(rawValue: UInt64) { self.rawValue = rawValue }

	public static let concurrent = Attributes(rawValue: 1<<1)

	@available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *)
	public static let initiallyInactive = Attributes(rawValue: 1<<2)

	fileprivate func _attr() -> dispatch_queue_attr_t? {
	var attr: dispatch_queue_attr_t? = nil

	if self.contains(.concurrent) {
	attr = _swift_dispatch_queue_concurrent()
	}
	if #available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *) {
	if self.contains(.initiallyInactive) {
	attr = CDispatch.dispatch_queue_attr_make_initially_inactive(attr)
	}
	}
	return attr
	}
	}

	public enum GlobalQueuePriority {
	@available(OSX, deprecated: 10.10, message: "Use qos attributes instead")
	@available(*, deprecated: 8.0, message: "Use qos attributes instead")
	case high

	@available(OSX, deprecated: 10.10, message: "Use qos attributes instead")
	@available(*, deprecated: 8.0, message: "Use qos attributes instead")
	case `default`

	@available(OSX, deprecated: 10.10, message: "Use qos attributes instead")
	@available(*, deprecated: 8.0, message: "Use qos attributes instead")
	case low

	@available(OSX, deprecated: 10.10, message: "Use qos attributes instead")
	@available(*, deprecated: 8.0, message: "Use qos attributes instead")
	case background

	internal var _translatedValue: Int {
	switch self {
	case .high: return 2 // DISPATCH_QUEUE_PRIORITY_HIGH
	case .default: return 0 // DISPATCH_QUEUE_PRIORITY_DEFAULT
	case .low: return -2 // DISPATCH_QUEUE_PRIORITY_LOW
	case .background: return Int(Int16.min) // DISPATCH_QUEUE_PRIORITY_BACKGROUND
	}
	}
	}

	public enum AutoreleaseFrequency {
	case inherit

	@available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *)
	case workItem

	@available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *)
	case never

	internal func _attr(attr: dispatch_queue_attr_t?) -> dispatch_queue_attr_t? {
	if #available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *) {
	switch self {
	case .inherit:
	// DISPATCH_AUTORELEASE_FREQUENCY_INHERIT
	return CDispatch.dispatch_queue_attr_make_with_autorelease_frequency(attr, dispatch_autorelease_frequency_t(0))
	case .workItem:
	// DISPATCH_AUTORELEASE_FREQUENCY_WORK_ITEM
	return CDispatch.dispatch_queue_attr_make_with_autorelease_frequency(attr, dispatch_autorelease_frequency_t(1))
	case .never:
	// DISPATCH_AUTORELEASE_FREQUENCY_NEVER
	return CDispatch.dispatch_queue_attr_make_with_autorelease_frequency(attr, dispatch_autorelease_frequency_t(2))
	}
	} else {
	return attr
	}
	}
	}

	public class func concurrentPerform(iterations: Int, execute work: (Int) -> Void) {
	_swift_dispatch_apply_current(iterations, work)
	}

	public class var main: DispatchQueue {
	return DispatchQueue(queue: _swift_dispatch_get_main_queue())
	}

	@available(OSX, deprecated: 10.10, message: "")
	@available(*, deprecated: 8.0, message: "")
	public class func global(priority: GlobalQueuePriority) -> DispatchQueue {
	return DispatchQueue(queue: CDispatch.dispatch_get_global_queue(priority._translatedValue, 0))
	}

	@available(OSX 10.10, iOS 8.0, *)
	public class func global(qos: DispatchQoS.QoSClass = .default) -> DispatchQueue {
	return DispatchQueue(queue: CDispatch.dispatch_get_global_queue(Int(qos.rawValue.rawValue), 0))
	}

	public class func getSpecific<T>(key: DispatchSpecificKey<T>) -> T? {
	let k = Unmanaged.passUnretained(key).toOpaque()
	if let p = CDispatch.dispatch_get_specific(k) {
	let v = Unmanaged<_DispatchSpecificValue<T>>
	.fromOpaque(p)
	.takeUnretainedValue()
	return v.value
	}
	return nil
	}

	public convenience init(
	label: String,
	qos: DispatchQoS = .unspecified,
	attributes: Attributes = [],
	autoreleaseFrequency: AutoreleaseFrequency = .inherit,
	target: DispatchQueue? = nil)
	{
	var attr = attributes._attr()
	if autoreleaseFrequency != .inherit {
	attr = autoreleaseFrequency._attr(attr: attr)
	}
	if #available(OSX 10.10, iOS 8.0, *), qos != .unspecified {
	attr = CDispatch.dispatch_queue_attr_make_with_qos_class(attr, qos.qosClass.rawValue.rawValue, Int32(qos.relativePriority))
	}

	if #available(OSX 10.12, iOS 10.0, tvOS 10.0, watchOS 3.0, *) {
	self.init(__label: label, attr: attr, queue: target)
	} else {
	self.init(__label: label, attr: attr)
	if let tq = target { self.setTarget(queue: tq) }
	}
	}

	public var label: String {
	return String(validatingUTF8: dispatch_queue_get_label(self.__wrapped))!
	}

	@available(OSX 10.10, iOS 8.0, *)
	public func sync(execute workItem: DispatchWorkItem) {
	CDispatch.dispatch_sync(self.__wrapped, workItem._block)
	}

	@available(OSX 10.10, iOS 8.0, *)
	public func async(execute workItem: DispatchWorkItem) {
	CDispatch.dispatch_async(self.__wrapped, workItem._block)
	}

	@available(OSX 10.10, iOS 8.0, *)
	public func async(group: DispatchGroup, execute workItem: DispatchWorkItem) {
	CDispatch.dispatch_group_async(group.__wrapped, self.__wrapped, workItem._block)
	}

	public func async(
	group: DispatchGroup? = nil,
	qos: DispatchQoS = .unspecified,
	flags: DispatchWorkItemFlags = [],
	execute work: @escaping @convention(block) () -> Void)
	{
	if group == nil && qos == .unspecified {
	// Fast-path route for the most common API usage
	if flags.isEmpty {
	CDispatch.dispatch_async(self.__wrapped, work)
	return
	} else if flags == .barrier {
	CDispatch.dispatch_barrier_async(self.__wrapped, work)
	return
	}
	}

	var block: @convention(block) () -> Void = work
	if #available(OSX 10.10, iOS 8.0, *), (qos != .unspecified \|\| !flags.isEmpty) {
	let workItem = DispatchWorkItem(qos: qos, flags: flags, block: work)
	block = workItem._block
	}

	if let g = group {
	CDispatch.dispatch_group_async(g.__wrapped, self.__wrapped, block)
	} else {
	CDispatch.dispatch_async(self.__wrapped, block)
	}
	}

	private func _syncBarrier(block: () -> ()) {
	CDispatch.dispatch_barrier_sync(self.__wrapped, block)
	}

	private func _syncHelper<T>(
	fn: (() -> ()) -> (),
	execute work: () throws -> T,
	rescue: ((Swift.Error) throws -> (T))) rethrows -> T
	{
	var result: T?
	var error: Swift.Error?
	withoutActuallyEscaping(work) { _work in
	fn {
	do {
	result = try _work()
	} catch let e {
	error = e
	}
	}
	}
	if let e = error {
	return try rescue(e)
	} else {
	return result!
	}
	}

	@available(OSX 10.10, iOS 8.0, *)
	private func _syncHelper<T>(
	fn: (DispatchWorkItem) -> (),
	flags: DispatchWorkItemFlags,
	execute work: () throws -> T,
	rescue: @escaping ((Swift.Error) throws -> (T))) rethrows -> T
	{
	var result: T?
	var error: Swift.Error?
	let workItem = DispatchWorkItem(flags: flags, noescapeBlock: {
	do {
	result = try work()
	} catch let e {
	error = e
	}
	})
	fn(workItem)
	if let e = error {
	return try rescue(e)
	} else {
	return result!
	}
	}

	public func sync<T>(execute work: () throws -> T) rethrows -> T {
	return try self._syncHelper(fn: sync, execute: work, rescue: { throw $0 })
	}

	public func sync<T>(flags: DispatchWorkItemFlags, execute work: () throws -> T) rethrows -> T {
	if flags == .barrier {
	return try self._syncHelper(fn: _syncBarrier, execute: work, rescue: { throw $0 })
	} else if #available(OSX 10.10, iOS 8.0, *), !flags.isEmpty {
	return try self._syncHelper(fn: sync, flags: flags, execute: work, rescue: { throw $0 })
	} else {
	return try self._syncHelper(fn: sync, execute: work, rescue: { throw $0 })
	}
	}

	public func asyncAfter(
	deadline: DispatchTime,
	qos: DispatchQoS = .unspecified,
	flags: DispatchWorkItemFlags = [],
	execute work: @escaping @convention(block) () -> Void)
	{
	if #available(OSX 10.10, iOS 8.0, *), qos != .unspecified \|\| !flags.isEmpty {
	let item = DispatchWorkItem(qos: qos, flags: flags, block: work)
	CDispatch.dispatch_after(deadline.rawValue, self.__wrapped, item._block)
	} else {
	CDispatch.dispatch_after(deadline.rawValue, self.__wrapped, work)
	}
	}

	public func asyncAfter(
	wallDeadline: DispatchWallTime,
	qos: DispatchQoS = .unspecified,
	flags: DispatchWorkItemFlags = [],
	execute work: @escaping @convention(block) () -> Void)
	{
	if #available(OSX 10.10, iOS 8.0, *), qos != .unspecified \|\| !flags.isEmpty {
	let item = DispatchWorkItem(qos: qos, flags: flags, block: work)
	CDispatch.dispatch_after(wallDeadline.rawValue, self.__wrapped, item._block)
	} else {
	CDispatch.dispatch_after(wallDeadline.rawValue, self.__wrapped, work)
	}
	}

	@available(OSX 10.10, iOS 8.0, *)
	public func asyncAfter(deadline: DispatchTime, execute: DispatchWorkItem) {
	CDispatch.dispatch_after(deadline.rawValue, self.__wrapped, execute._block)
	}

	@available(OSX 10.10, iOS 8.0, *)
	public func asyncAfter(wallDeadline: DispatchWallTime, execute: DispatchWorkItem) {
	CDispatch.dispatch_after(wallDeadline.rawValue, self.__wrapped, execute._block)
	}

	@available(OSX 10.10, iOS 8.0, *)
	public var qos: DispatchQoS {
	var relPri: Int32 = 0
	let cls = DispatchQoS.QoSClass(rawValue: _OSQoSClass(qosClass: dispatch_queue_get_qos_class(self.__wrapped, &relPri))!)!
	return DispatchQoS(qosClass: cls, relativePriority: Int(relPri))
	}

	public func getSpecific<T>(key: DispatchSpecificKey<T>) -> T? {
	let k = Unmanaged.passUnretained(key).toOpaque()
	if let p = dispatch_queue_get_specific(self.__wrapped, k) {
	let v = Unmanaged<_DispatchSpecificValue<T>>
	.fromOpaque(p)
	.takeUnretainedValue()
	return v.value
	}
	return nil
	}

	public func setSpecific<T>(key: DispatchSpecificKey<T>, value: T?) {
	let k = Unmanaged.passUnretained(key).toOpaque()
	let v = value.flatMap { _DispatchSpecificValue(value: $0) }
	let p = v.flatMap { Unmanaged.passRetained($0).toOpaque() }
	dispatch_queue_set_specific(self.__wrapped, k, p, _destructDispatchSpecificValue)
	}

	#if os(Android)
	public static func setThreadDetachCallback(_ cb: @escaping @convention(c) () -> Void) {
	_dispatch_install_thread_detach_callback(cb)
	}
	#endif
	}

	private func _destructDispatchSpecificValue(ptr: UnsafeMutableRawPointer?) {
	if let p = ptr {
	Unmanaged<AnyObject>.fromOpaque(p).release()
	}
	}