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//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
import SWBUtil
/// Provides a cache of objects keyed by a tuple of a path, and signature representing a hash of the contents at that path.
final class FileSystemSignatureBasedCache<Value: Sendable>: Sendable {
private struct Key: Hashable, Sendable {
let path: Path
let filesSignature: FilesSignature
}
private let cache = Cache<Key, Lazy<Result<Value, any Error>>>()
private let block: @Sendable (Path) throws -> Value
/// Initializes a cache.
/// - parameter block: A block which computes the object keyed by the given path. It is the caller's responsibility to access the actual filesystem.
init(_ block: @escaping @Sendable (Path) throws -> Value) {
self.block = block
}
/// Gets the object with the given path and signature, creating it if necessary.
public func get(at path: Path, filesSignature: FilesSignature) throws -> Value {
return try cache.getOrInsert(Key(path: path, filesSignature: filesSignature), body: { () -> Result<Value, any Error> in
return Result<Value, any Error> {
try block(path)
}
}).get()
}
}
protocol FileSystemInitializable {
init(path: Path, fs: any FSProxy) throws
}
extension FileSystemSignatureBasedCache where Value: FileSystemInitializable {
convenience init(fs: any FSProxy) {
self.init { path in
try Value(path: path, fs: fs)
}
}
}
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