48 lines
1.7 KiB
Swift
48 lines
1.7 KiB
Swift
//===----------------------------------------------------------------------===//
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//
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// This source file is part of the SwiftNIO open source project
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//
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// Copyright (c) 2020 Apple Inc. and the SwiftNIO project authors
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// Licensed under Apache License v2.0
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//
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// See LICENSE.txt for license information
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// See CONTRIBUTORS.txt for the list of SwiftNIO project authors
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//
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// SPDX-License-Identifier: Apache-2.0
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//
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//===----------------------------------------------------------------------===//
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import Dispatch
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extension DispatchQueue {
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/// Schedules a work item for immediate execution and immediately returns with an `EventLoopFuture` providing the
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/// result. For example:
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///
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/// let futureResult = DispatchQueue.main.asyncWithFuture(eventLoop: myEventLoop) { () -> String in
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/// callbackMayBlock()
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/// }
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/// try let value = futureResult.wait()
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///
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/// - parameters:
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/// - eventLoop: the `EventLoop` on which to processes the IO / task specified by `callbackMayBlock`.
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/// - callbackMayBlock: The scheduled callback for the IO / task.
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/// - returns a new `EventLoopFuture<ReturnType>` with value returned by the `block` parameter.
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@inlinable
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public func asyncWithFuture<NewValue>(
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eventLoop: EventLoop,
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_ callbackMayBlock: @escaping () throws -> NewValue
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) -> EventLoopFuture<NewValue> {
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let promise = eventLoop.makePromise(of: NewValue.self)
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self.async {
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do {
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let result = try callbackMayBlock()
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promise.succeed(result)
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} catch {
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promise.fail(error)
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}
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}
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return promise.futureResult
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}
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}
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