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
  41         public init(qos: DispatchQoS = .unspecified, flags: DispatchWorkItemFlags = [], block: @escaping @convention(block) () -> ()) {
  42                 _block =  dispatch_block_create_with_qos_class(dispatch_block_flags_t(flags.rawValue),
  43                         qos.qosClass.rawValue.rawValue, Int32(qos.relativePriority), block)
  44         }
  45
  46         // Used by DispatchQueue.synchronously<T> to provide a path through
  47         // dispatch_block_t, as we know the lifetime of the block in question.
  48         internal init(flags: DispatchWorkItemFlags = [], noescapeBlock: () -> ()) {
  49                 _block = _swift_dispatch_block_create_noescape(dispatch_block_flags_t(flags.rawValue), noescapeBlock)
  50         }
  51
  52         public func perform() {
  53                 _block()
  54         }
  55
  56         public func wait() {
  57                 _ = dispatch_block_wait(_block, DispatchTime.distantFuture.rawValue)
  58         }
  59
  60         public func wait(timeout: DispatchTime) -> DispatchTimeoutResult {
  61                 return dispatch_block_wait(_block, timeout.rawValue) == 0 ? .success : .timedOut
  62         }
  63
  64         public func wait(wallTimeout: DispatchWallTime) -> DispatchTimeoutResult {
  65                 return dispatch_block_wait(_block, wallTimeout.rawValue) == 0 ? .success : .timedOut
  66         }
  67
  68         public func notify(
  69                 qos: DispatchQoS = .unspecified,
  70                 flags: DispatchWorkItemFlags = [],
  71                 queue: DispatchQueue,
  72                 execute: @escaping @convention(block) () -> ())
  73         {
  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 /// The dispatch_block_t typealias is different from usual closures in that it
  96 /// uses @convention(block). This is to avoid unnecessary bridging between
  97 /// C blocks and Swift closures, which interferes with dispatch APIs that depend
  98 /// on the referential identity of a block. Particularly, dispatch_block_create.
  99 internal typealias _DispatchBlock = @convention(block) () -> Void
 100 internal typealias dispatch_block_t = @convention(block) () -> Void
 101
 102 @_silgen_name("_swift_dispatch_block_create_noescape")
 103 internal func _swift_dispatch_block_create_noescape(_ flags: dispatch_block_flags_t, _ block: () -> ()) -> _DispatchBlock