Created
May 23, 2024 00:31
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import Foundation | |
struct TimeoutError: Error {} | |
extension Result where Failure == any Error { | |
init(catching: () async throws -> Success) async { | |
do { | |
self = .success(try await catching()) | |
} catch { | |
self = .failure(error) | |
} | |
} | |
} | |
final class SingleSink<T>: @unchecked Sendable { | |
init(con: CheckedContinuation<T, any Error>) { | |
self.con = con | |
} | |
let lock = NSLock() | |
let con: CheckedContinuation<T, any Error> | |
var isCompleted = false | |
func send(result: Result<T, any Error>) { | |
lock.withLock { | |
if isCompleted { return } | |
isCompleted = true | |
con.resume(with: result) | |
} | |
} | |
} | |
struct GuaranteedCheckedContinuation<T> { | |
var sink: SingleSink<T> | |
func resume(with result: Result<T, any Error>) { | |
sink.send(result: result) | |
} | |
} | |
func withGuaranteedCheckedContinuation<T>( | |
timeout: Duration, | |
_ body: (GuaranteedCheckedContinuation<T>) -> Void | |
) async throws -> T { | |
return try await withCheckedThrowingContinuation { (con) in | |
let sink = SingleSink(con: con) | |
let gcon = GuaranteedCheckedContinuation(sink: sink) | |
body(gcon) | |
Task { | |
try await Task.sleep(for: timeout) | |
gcon.resume(with: .failure(TimeoutError())) | |
} | |
} | |
} | |
// 自由な処理 | |
func myAsyncProc(timeout: Duration) async throws { | |
try await withGuaranteedCheckedContinuation(timeout: timeout) { (con: GuaranteedCheckedContinuation<Void>) in | |
// しかしバグがあり、con.resumeが呼ばれることはない | |
} | |
} | |
func main() async throws { | |
// 自由な処理に、タイムアウトを設定して呼び出す | |
do { | |
try await myAsyncProc(timeout: .seconds(1)) | |
print("proc completed") | |
} catch { | |
if error is TimeoutError { | |
// それでも1秒後にタイムアウトする | |
print("timeout") | |
} else { | |
fatalError("error: \(error)") | |
} | |
} | |
} | |
try await main() |
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