35 lines
1.2 KiB
Swift
35 lines
1.2 KiB
Swift
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// SPDX-License-Identifier: MIT
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// Copyright © 2018-2019 WireGuard LLC. All Rights Reserved.
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import Foundation
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extension Array {
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/// Returns an array containing the results of mapping the given closure over the sequence’s
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/// elements concurrently.
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///
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/// - Parameters:
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/// - queue: The queue for performing concurrent computations.
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/// If the given queue is serial, the values are mapped in a serial fashion.
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/// Pass `nil` to perform computations on the current queue.
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/// - transform: the block to perform concurrent computations over the given element.
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/// - Returns: an array of concurrently computed values.
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func concurrentMap<U>(queue: DispatchQueue?, _ transform: (Element) -> U) -> [U] {
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var result = [U?](repeating: nil, count: self.count)
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let resultQueue = DispatchQueue(label: "ConcurrentMapQueue")
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let execute = queue?.sync ?? { $0() }
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execute {
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DispatchQueue.concurrentPerform(iterations: self.count) { (index) in
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let value = transform(self[index])
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resultQueue.sync {
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result[index] = value
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}
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}
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}
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return result.map { $0! }
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}
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}
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