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