// // StatusPrefetchingService.swift // Mastodon // // Created by MainasuK Cirno on 2021-3-10. // import os.log import Foundation import Combine import CoreData import CoreDataStack import MastodonSDK import MastodonMeta final class StatusPrefetchingService { typealias TaskID = String typealias StatusObjectID = NSManagedObjectID let workingQueue = DispatchQueue(label: "org.joinmastodon.app.StatusPrefetchingService.working-queue") // StatusContentOperation let statusContentOperationQueue: OperationQueue = { let queue = OperationQueue() queue.name = "org.joinmastodon.app.StatusPrefetchingService.statusContentOperationQueue" queue.maxConcurrentOperationCount = 2 return queue }() var statusContentOperations: [StatusObjectID: StatusContentOperation] = [:] var disposeBag = Set() private(set) var statusPrefetchingDisposeBagDict: [TaskID: AnyCancellable] = [:] // input weak var apiService: APIService? let managedObjectContext: NSManagedObjectContext let backgroundManagedObjectContext: NSManagedObjectContext // read-only init( managedObjectContext: NSManagedObjectContext, backgroundManagedObjectContext: NSManagedObjectContext, apiService: APIService ) { self.managedObjectContext = managedObjectContext self.backgroundManagedObjectContext = backgroundManagedObjectContext self.apiService = apiService } private func status(from statusObjectItem: StatusObjectItem) -> Status? { assert(Thread.isMainThread) switch statusObjectItem { case .homeTimelineIndex(let objectID): let homeTimelineIndex = try? managedObjectContext.existingObject(with: objectID) as? HomeTimelineIndex return homeTimelineIndex?.status case .mastodonNotification(let objectID): let mastodonNotification = try? managedObjectContext.existingObject(with: objectID) as? MastodonNotification return mastodonNotification?.status case .status(let objectID): let status = try? managedObjectContext.existingObject(with: objectID) as? Status return status } } } extension StatusPrefetchingService { func prefetch(statusObjectItems items: [StatusObjectItem]) { for item in items { guard let status = status(from: item), !status.isDeleted else { continue } // status content parser task if statusContentOperations[status.objectID] == nil { let mastodonContent = MastodonContent( content: (status.reblog ?? status).content, emojis: (status.reblog ?? status).emojiMeta ) let operation = StatusContentOperation( statusObjectID: status.objectID, mastodonContent: mastodonContent ) statusContentOperations[status.objectID] = operation statusContentOperationQueue.addOperation(operation) } } } func cancelPrefetch(statusObjectItems items: [StatusObjectItem]) { for item in items { guard let status = status(from: item), !status.isDeleted else { continue } // cancel status content parser task statusContentOperations.removeValue(forKey: status.objectID)?.cancel() } } } extension StatusPrefetchingService { func prefetchReplyTo( domain: String, statusObjectID: NSManagedObjectID, statusID: Mastodon.Entity.Status.ID, replyToStatusID: Mastodon.Entity.Status.ID, authorizationBox: MastodonAuthenticationBox ) { workingQueue.async { [weak self] in guard let self = self, let apiService = self.apiService else { return } let taskID = domain + "@" + statusID + "->" + replyToStatusID guard self.statusPrefetchingDisposeBagDict[taskID] == nil else { return } os_log(.info, log: .debug, "%{public}s[%{public}ld], %{public}s: prefetching replyTo: %s", ((#file as NSString).lastPathComponent), #line, #function, taskID) self.statusPrefetchingDisposeBagDict[taskID] = apiService.status( domain: domain, statusID: replyToStatusID, authorizationBox: authorizationBox ) .sink(receiveCompletion: { [weak self] completion in // remove task when completed guard let self = self else { return } os_log(.info, log: .debug, "%{public}s[%{public}ld], %{public}s: prefeched replyTo: %s", ((#file as NSString).lastPathComponent), #line, #function, taskID) self.statusPrefetchingDisposeBagDict[taskID] = nil }, receiveValue: { [weak self] _ in guard let self = self else { return } let backgroundManagedObjectContext = apiService.backgroundManagedObjectContext backgroundManagedObjectContext.performChanges { guard let status = backgroundManagedObjectContext.object(with: statusObjectID) as? Status else { return } do { let predicate = Status.predicate(domain: domain, id: replyToStatusID) let request = Status.sortedFetchRequest request.predicate = predicate request.returnsObjectsAsFaults = false request.fetchLimit = 1 guard let replyTo = try backgroundManagedObjectContext.fetch(request).first else { return } status.update(replyTo: replyTo) } catch { assertionFailure(error.localizedDescription) } } .sink { _ in os_log(.info, log: .debug, "%{public}s[%{public}ld], %{public}s: update status replyTo: %s", ((#file as NSString).lastPathComponent), #line, #function, taskID) } receiveValue: { _ in // do nothing } .store(in: &self.disposeBag) }) } } }