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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2020 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
import Foundation
import struct TSCBasic.AbsolutePath
/// The set of known SourceKitD instances, uniqued by path.
///
/// It is not generally safe to have two instances of SourceKitD for the same libsourcekitd, so
/// care is taken to ensure that there is only ever one instance per path.
///
/// * To get a new instance, use `getOrAdd("path", create: { NewSourceKitD() })`.
/// * To remove an existing instance, use `remove("path")`, but be aware that if there are any other
/// references to the instances in the program, it can be resurrected if `getOrAdd` is called with
/// the same path. See note on `remove(_:)`
public actor SourceKitDRegistry {
/// Mapping from path to active SourceKitD instance.
private var active: [AbsolutePath: SourceKitD] = [:]
/// Instances that have been unregistered, but may be resurrected if accessed before destruction.
private var cemetary: [AbsolutePath: WeakSourceKitD] = [:]
/// Initialize an empty registry.
public init() {}
/// The global shared SourceKitD registry.
public static let shared: SourceKitDRegistry = SourceKitDRegistry()
/// Returns the existing SourceKitD for the given path, or creates it and registers it.
public func getOrAdd(
_ key: AbsolutePath,
create: @Sendable () throws -> SourceKitD
) rethrows -> SourceKitD {
if let existing = active[key] {
return existing
}
if let resurrected = cemetary[key]?.value {
cemetary[key] = nil
active[key] = resurrected
return resurrected
}
let newValue = try create()
active[key] = newValue
return newValue
}
/// Removes the SourceKitD instance registered for the given path, if any, from the set of active
/// instances.
///
/// Since it is not generally safe to have two sourcekitd connections at once, the existing value
/// is converted to a weak reference until it is no longer referenced anywhere by the program. If
/// the same path is looked up again before the original service is deinitialized, the original
/// service is resurrected rather than creating a new instance.
public func remove(_ key: AbsolutePath) -> SourceKitD? {
let existing = active.removeValue(forKey: key)
if let existing = existing {
assert(self.cemetary[key]?.value == nil)
cemetary[key] = WeakSourceKitD(value: existing)
}
return existing
}
}
fileprivate struct WeakSourceKitD {
weak var value: SourceKitD?
}
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