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28f96e64ab
If you use SwiftStdlibCurrentOS availability, you will be able to use new types and functions from within the implementation. This works by, when appropriate, building with the CurrentOS availability set to the current deployment target. rdar://150944675
70 lines
2.7 KiB
Swift
70 lines
2.7 KiB
Swift
//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2020 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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import Swift
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// None of TaskExecutor APIs are available in task-to-thread concurrency model.
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#if !SWIFT_STDLIB_TASK_TO_THREAD_MODEL_CONCURRENCY
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/// The global concurrent executor that is used by default for Swift Concurrency
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/// tasks.
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///
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/// The executor's implementation is platform dependent.
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/// By default it uses a fixed size pool of threads and should not be used for
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/// blocking operations which do not guarantee forward progress as doing so may
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/// prevent other tasks from being executed and render the system unresponsive.
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///
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/// You may pass this executor explicitly to a ``Task`` initializer as a task
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/// executor preference, in order to ensure and document that task be executed
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/// on the global executor, instead e.g. inheriting the enclosing actor's
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/// executor. Refer to ``withTaskExecutorPreference(_:operation:)`` for a
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/// detailed discussion of task executor preferences.
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///
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/// Customizing the global concurrent executor is currently not supported.
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@available(SwiftStdlib 6.0, *)
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@available(*, deprecated, renamed: "Task.defaultExecutor")
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@_unavailableInEmbedded
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public var globalConcurrentExecutor: any TaskExecutor {
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get {
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if #available(SwiftStdlibCurrentOS 6.2, *) {
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return Task.defaultExecutor
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} else {
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fatalError("we shouldn't get here; if we have, availability is broken")
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}
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}
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}
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/// A task executor which enqueues all work on the default global concurrent
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/// thread pool that is used as the default executor for Swift concurrency
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/// tasks.
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@available(SwiftStdlib 6.0, *)
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@_unavailableInEmbedded
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internal final class _DefaultGlobalConcurrentExecutor: TaskExecutor {
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public static let shared: _DefaultGlobalConcurrentExecutor = .init()
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private init() {}
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public func enqueue(_ job: consuming ExecutorJob) {
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_enqueueJobGlobal(UnownedJob(job)._context)
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}
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public func asUnownedTaskExecutor() -> UnownedTaskExecutor {
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// The "default global concurrent executor" is simply the "undefined" one.
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// We represent it as the `(0, 0)` ExecutorRef and it is handled properly
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// by the runtime, without having to call through to the
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// `_DefaultGlobalConcurrentExecutor` declared in Swift.
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unsafe UnownedTaskExecutor(_getUndefinedTaskExecutor())
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}
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}
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#endif
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