src/swift/Block.swift

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // This source file is part of the Swift.org open source project
   4 //
   5 // Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
   6 // Licensed under Apache License v2.0 with Runtime Library Exception
   7 //
   8 // See http://swift.org/LICENSE.txt for license information
   9 // See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 import CDispatch
  14
  15 public struct DispatchWorkItemFlags : OptionSet, RawRepresentable {
  16         public let rawValue: UInt
  17         public init(rawValue: UInt) { self.rawValue = rawValue }
  18
  19         public static let barrier = DispatchWorkItemFlags(rawValue: 0x1)
  20
  21         @available(OSX 10.10, iOS 8.0, *)
  22         public static let detached = DispatchWorkItemFlags(rawValue: 0x2)
  23
  24         @available(OSX 10.10, iOS 8.0, *)
  25         public static let assignCurrentContext = DispatchWorkItemFlags(rawValue: 0x4)
  26
  27         @available(OSX 10.10, iOS 8.0, *)
  28         public static let noQoS = DispatchWorkItemFlags(rawValue: 0x8)
  29
  30         @available(OSX 10.10, iOS 8.0, *)
  31         public static let inheritQoS = DispatchWorkItemFlags(rawValue: 0x10)
  32
  33         @available(OSX 10.10, iOS 8.0, *)
  34         public static let enforceQoS = DispatchWorkItemFlags(rawValue: 0x20)
  35 }
  36
  37 @available(OSX 10.10, iOS 8.0, *)
  38 public class DispatchWorkItem {
  39         internal var _block: _DispatchBlock
  40         internal var _group: DispatchGroup?
  41
  42         public init(group: DispatchGroup? = nil, qos: DispatchQoS = .unspecified, flags: DispatchWorkItemFlags = [], block: @convention(block) () -> ()) {
  43                 _block =  dispatch_block_create_with_qos_class(dispatch_block_flags_t(flags.rawValue),
  44                         qos.qosClass.rawValue.rawValue, Int32(qos.relativePriority), block)
  45         }
  46
  47         // Used by DispatchQueue.synchronously<T> to provide a @noescape path through
  48         // dispatch_block_t, as we know the lifetime of the block in question.
  49         internal init(flags: DispatchWorkItemFlags = [], noescapeBlock: @noescape () -> ()) {
  50                 _block = _swift_dispatch_block_create_noescape(dispatch_block_flags_t(flags.rawValue), noescapeBlock)
  51         }
  52
  53         public func perform() {
  54                 if let g = _group {
  55                         g.enter()
  56                         defer { g.leave() }
  57                 }
  58                 _block()
  59         }
  60
  61         public func wait() {
  62                 _ = dispatch_block_wait(_block, DispatchTime.distantFuture.rawValue)
  63         }
  64
  65         public func wait(timeout: DispatchTime) -> DispatchTimeoutResult {
  66                 return dispatch_block_wait(_block, timeout.rawValue) == 0 ? .Success : .TimedOut
  67         }
  68
  69         public func wait(wallTimeout: DispatchWallTime) -> DispatchTimeoutResult {
  70                 return dispatch_block_wait(_block, wallTimeout.rawValue) == 0 ? .Success : .TimedOut
  71         }
  72
  73         public func notify(qos: DispatchQoS = .unspecified, flags: DispatchWorkItemFlags = [], queue: DispatchQueue, execute: @convention(block) () -> Void) {
  74                 if qos != .unspecified || !flags.isEmpty {
  75                         let item = DispatchWorkItem(qos: qos, flags: flags, block: execute)
  76                         dispatch_block_notify(_block, queue.__wrapped, item._block)
  77                 } else {
  78                         dispatch_block_notify(_block, queue.__wrapped, execute)
  79                 }
  80         }
  81
  82         public func notify(queue: DispatchQueue, execute: DispatchWorkItem) {
  83                 dispatch_block_notify(_block, queue.__wrapped, execute._block)
  84         }
  85
  86         public func cancel() {
  87                 dispatch_block_cancel(_block)
  88         }
  89
  90         public var isCancelled: Bool {
  91                 return dispatch_block_testcancel(_block) != 0
  92         }
  93 }
  94
  95 @available(OSX 10.10, iOS 8.0, *)
  96 public extension DispatchWorkItem {
  97         @available(*, deprecated, renamed: "DispatchWorkItem.wait(self:wallTimeout:)")
  98         public func wait(timeout: DispatchWallTime) -> Int {
  99                 switch wait(wallTimeout: timeout) {
 100                 case .Success: return 0
 101                 case .TimedOut: return DispatchTimeoutResult.KERN_OPERATION_TIMED_OUT
 102                 }
 103         }
 104 }
 105
 106 /// The dispatch_block_t typealias is different from usual closures in that it
 107 /// uses @convention(block). This is to avoid unnecessary bridging between
 108 /// C blocks and Swift closures, which interferes with dispatch APIs that depend
 109 /// on the referential identity of a block. Particularly, dispatch_block_create.
 110 internal typealias _DispatchBlock = @convention(block) () -> Void
 111 internal typealias dispatch_block_t = @convention(block) () -> Void
 112
 113 @_silgen_name("_swift_dispatch_block_create_noescape")
 114 internal func _swift_dispatch_block_create_noescape(_ flags: dispatch_block_flags_t, _ block: @noescape () -> ()) -> _DispatchBlock