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// Foundation/URLSession/TaskRegistry.swift - URLSession & libcurl
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2016 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
//
// -----------------------------------------------------------------------------
///
/// These are libcurl helpers for the URLSession API code.
/// - SeeAlso: https://curl.haxx.se/libcurl/c/
/// - SeeAlso: URLSession.swift
///
// -----------------------------------------------------------------------------
#if os(macOS) || os(iOS) || os(watchOS) || os(tvOS)
import SwiftFoundation
#else
import Foundation
#endif
import Dispatch
extension URLSession {
/// This helper class keeps track of all tasks, and their behaviours.
///
/// Each `URLSession` has a `TaskRegistry` for its running tasks. The
/// *behaviour* defines what action is to be taken e.g. upon completion.
/// The behaviour stores the completion handler for tasks that are
/// completion handler based.
///
/// - Note: This must **only** be accessed on the owning session's work queue.
class _TaskRegistry {
/// Completion handler for `URLSessionDataTask`, and `URLSessionUploadTask`.
typealias DataTaskCompletion = @Sendable (Data?, URLResponse?, Error?) -> Void
/// Completion handler for `URLSessionDownloadTask`.
typealias DownloadTaskCompletion = @Sendable (URL?, URLResponse?, Error?) -> Void
/// What to do upon events (such as completion) of a specific task.
enum _Behaviour {
/// Call the `URLSession`s delegate
case callDelegate
/// Default action for all events, except for completion.
case dataCompletionHandler(DataTaskCompletion)
/// Default action for all asynchronous events.
case dataCompletionHandlerWithTaskDelegate(DataTaskCompletion, URLSessionTaskDelegate?)
/// Default action for all events, except for completion.
case downloadCompletionHandler(DownloadTaskCompletion)
/// Default action for all asynchronous events.
case downloadCompletionHandlerWithTaskDelegate(DownloadTaskCompletion, URLSessionTaskDelegate?)
}
fileprivate var tasks: [Int: URLSessionTask] = [:]
fileprivate var behaviours: [Int: _Behaviour] = [:]
fileprivate var tasksFinishedCallback: (() -> Void)?
}
}
extension URLSession._TaskRegistry {
/// Add a task
///
/// - Note: This must **only** be accessed on the owning session's work queue.
func add(_ task: URLSessionTask, behaviour: _Behaviour) {
let identifier = task.taskIdentifier
guard identifier != 0 else { fatalError("Invalid task identifier") }
guard tasks.index(forKey: identifier) == nil else {
if tasks[identifier] === task {
fatalError("Trying to re-insert a task that's already in the registry.")
} else {
fatalError("Trying to insert a task, but a different task with the same identifier is already in the registry.")
}
}
tasks[identifier] = task
behaviours[identifier] = behaviour
}
/// Remove a task
///
/// - Note: This must **only** be accessed on the owning session's work queue.
func remove(_ task: URLSessionTask) {
let identifier = task.taskIdentifier
guard identifier != 0 else { fatalError("Invalid task identifier") }
guard let tasksIdx = tasks.index(forKey: identifier) else {
fatalError("Trying to remove task, but it's not in the registry.")
}
tasks.remove(at: tasksIdx)
guard let behaviourIdx = behaviours.index(forKey: identifier) else {
fatalError("Trying to remove task's behaviour, but it's not in the registry.")
}
behaviours.remove(at: behaviourIdx)
guard let allTasksFinished = tasksFinishedCallback else { return }
if self.isEmpty {
allTasksFinished()
}
}
func notify(on tasksCompletion: @escaping () -> Void) {
tasksFinishedCallback = tasksCompletion
}
var isEmpty: Bool {
return tasks.isEmpty
}
var allTasks: [URLSessionTask] {
return tasks.map { $0.value }
}
}
extension URLSession._TaskRegistry {
/// The behaviour that's registered for the given task.
///
/// - Note: It is a programming error to pass a task that isn't registered.
/// - Note: This must **only** be accessed on the owning session's work queue.
func behaviour(for task: URLSessionTask) -> _Behaviour {
guard let b = behaviours[task.taskIdentifier] else {
fatalError("Trying to access a behaviour for a task that in not in the registry.")
}
return b
}
}
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