//
|
// SessionDataTask.swift
|
// Kingfisher
|
//
|
// Created by Wei Wang on 2018/11/1.
|
//
|
// Copyright (c) 2019 Wei Wang <onevcat@gmail.com>
|
//
|
// Permission is hereby granted, free of charge, to any person obtaining a copy
|
// of this software and associated documentation files (the "Software"), to deal
|
// in the Software without restriction, including without limitation the rights
|
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
// copies of the Software, and to permit persons to whom the Software is
|
// furnished to do so, subject to the following conditions:
|
//
|
// The above copyright notice and this permission notice shall be included in
|
// all copies or substantial portions of the Software.
|
//
|
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
// THE SOFTWARE.
|
|
import Foundation
|
|
/// Represents a session data task in `ImageDownloader`. It consists of an underlying `URLSessionDataTask` and
|
/// an array of `TaskCallback`. Multiple `TaskCallback`s could be added for a single downloading data task.
|
public class SessionDataTask {
|
|
/// Represents the type of token which used for cancelling a task.
|
public typealias CancelToken = Int
|
|
struct TaskCallback {
|
let onCompleted: Delegate<Result<ImageLoadingResult, KingfisherError>, Void>?
|
let options: KingfisherParsedOptionsInfo
|
}
|
|
/// Downloaded raw data of current task.
|
public private(set) var mutableData: Data
|
|
/// The underlying download task. It is only for debugging purpose when you encountered an error. You should not
|
/// modify the content of this task or start it yourself.
|
public let task: URLSessionDataTask
|
private var callbacksStore = [CancelToken: TaskCallback]()
|
|
var callbacks: [SessionDataTask.TaskCallback] {
|
lock.lock()
|
defer { lock.unlock() }
|
return Array(callbacksStore.values)
|
}
|
|
private var currentToken = 0
|
private let lock = NSLock()
|
|
let onTaskDone = Delegate<(Result<(Data, URLResponse?), KingfisherError>, [TaskCallback]), Void>()
|
let onCallbackCancelled = Delegate<(CancelToken, TaskCallback), Void>()
|
|
var started = false
|
var containsCallbacks: Bool {
|
// We should be able to use `task.state != .running` to check it.
|
// However, in some rare cases, cancelling the task does not change
|
// task state to `.cancelling` immediately, but still in `.running`.
|
// So we need to check callbacks count to for sure that it is safe to remove the
|
// task in delegate.
|
return !callbacks.isEmpty
|
}
|
|
init(task: URLSessionDataTask) {
|
self.task = task
|
mutableData = Data()
|
}
|
|
func addCallback(_ callback: TaskCallback) -> CancelToken {
|
lock.lock()
|
defer { lock.unlock() }
|
callbacksStore[currentToken] = callback
|
defer { currentToken += 1 }
|
return currentToken
|
}
|
|
func removeCallback(_ token: CancelToken) -> TaskCallback? {
|
lock.lock()
|
defer { lock.unlock() }
|
if let callback = callbacksStore[token] {
|
callbacksStore[token] = nil
|
return callback
|
}
|
return nil
|
}
|
|
func resume() {
|
guard !started else { return }
|
started = true
|
task.resume()
|
}
|
|
func cancel(token: CancelToken) {
|
guard let callback = removeCallback(token) else {
|
return
|
}
|
if callbacksStore.count == 0 {
|
task.cancel()
|
}
|
onCallbackCancelled.call((token, callback))
|
}
|
|
func forceCancel() {
|
for token in callbacksStore.keys {
|
cancel(token: token)
|
}
|
}
|
|
func didReceiveData(_ data: Data) {
|
mutableData.append(data)
|
}
|
}
|
