File: AsyncSingleValueCache.swift

package info (click to toggle)
swiftlang 6.2.3-1
  • links: PTS, VCS
  • area: main
  • in suites: forky, sid
  • size: 2,856,264 kB
  • sloc: cpp: 9,995,718; ansic: 2,234,019; asm: 1,092,167; python: 313,940; objc: 82,726; f90: 80,126; lisp: 38,373; pascal: 25,580; sh: 20,378; ml: 5,058; perl: 4,751; makefile: 4,725; awk: 3,535; javascript: 3,018; xml: 918; fortran: 664; cs: 573; ruby: 396
file content (29 lines) | stat: -rw-r--r-- 1,055 bytes parent folder | download 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
 
//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift open source project
//
// Copyright (c) 2025 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

public struct AsyncSingleValueCache<Value: Sendable, E: Error>: ~Copyable, Sendable {
    private let value = AsyncLockedValue<Value?>(nil)

    public init() { }

    public func value(body: sending () async throws(E) -> sending Value) async throws(E) -> sending Value {
        try await value.withLock { value throws(E) in
            if let value {
                return value
            } else {
                let newValue = try await body()
                value = newValue
                return newValue
            }
        }
    }
}