frenzy-ios/Reader/CoreData/PersistentContainer.swift

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//
// PersistentContainer.swift
// Reader
//
// Created by Shadowfacts on 12/24/21.
//
import CoreData
import Fervor
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import OSLog
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class PersistentContainer: NSPersistentContainer {
private static let managedObjectModel: NSManagedObjectModel = {
let url = Bundle.main.url(forResource: "Reader", withExtension: "momd")!
return NSManagedObjectModel(contentsOf: url)!
}()
private(set) lazy var backgroundContext: NSManagedObjectContext = {
let context = NSManagedObjectContext(concurrencyType: .privateQueueConcurrencyType)
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// todo: should the background context really be parented to the view context, or should they both be direct children of the PSC?
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context.parent = self.viewContext
return context
}()
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private weak var fervorController: FervorController?
private let logger = Logger(subsystem: Bundle.main.bundleIdentifier!, category: "PersistentContainer")
init(account: LocalData.Account, fervorController: FervorController) {
self.fervorController = fervorController
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super.init(name: "\(account.id)", managedObjectModel: PersistentContainer.managedObjectModel)
loadPersistentStores { description, error in
if let error = error {
fatalError("Unable to load persistent store: \(error)")
}
}
}
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@MainActor
private func saveViewContext() async throws {
if viewContext.hasChanges {
try viewContext.save()
}
}
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func lastSyncDate() async throws -> Date? {
return try await backgroundContext.perform {
let state = try self.backgroundContext.fetch(SyncState.fetchRequest()).first
return state?.lastSync
}
}
func updateLastSyncDate(_ date: Date) async throws {
try await backgroundContext.perform {
if let state = try self.backgroundContext.fetch(SyncState.fetchRequest()).first {
state.lastSync = date
} else {
let state = SyncState(context: self.backgroundContext)
state.lastSync = date
}
try self.backgroundContext.save()
}
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try await self.saveViewContext()
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}
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func sync(serverGroups: [Fervor.Group], serverFeeds: [Fervor.Feed]) async throws {
try await backgroundContext.perform {
let existingGroups = try self.backgroundContext.fetch(Group.fetchRequest())
for group in serverGroups {
if let existing = existingGroups.first(where: { $0.id == group.id }) {
existing.updateFromServer(group)
} else {
let mo = Group(context: self.backgroundContext)
mo.updateFromServer(group)
}
}
for removed in existingGroups where !serverGroups.contains(where: { $0.id == removed.id }) {
self.backgroundContext.delete(removed)
}
let existingFeeds = try self.backgroundContext.fetch(Feed.fetchRequest())
for feed in serverFeeds {
if let existing = existingFeeds.first(where: { $0.id == feed.id }) {
existing.updateFromServer(feed)
} else {
let mo = Feed(context: self.backgroundContext)
mo.updateFromServer(feed)
}
}
if self.backgroundContext.hasChanges {
try self.backgroundContext.save()
}
}
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try await self.saveViewContext()
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}
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func syncItems(_ syncUpdate: ItemsSyncUpdate) async throws {
try await backgroundContext.perform {
self.logger.debug("syncItems: deleting \(syncUpdate.delete.count, privacy: .public) items")
let deleteReq = Item.fetchRequest()
deleteReq.predicate = NSPredicate(format: "id in %@", syncUpdate.delete)
let delete = NSBatchDeleteRequest(fetchRequest: deleteReq as! NSFetchRequest<NSFetchRequestResult>)
delete.resultType = .resultTypeObjectIDs
let result = try self.backgroundContext.execute(delete)
if let deleteResult = result as? NSBatchDeleteResult,
let objectIDs = deleteResult.result as? [NSManagedObjectID] {
NSManagedObjectContext.mergeChanges(fromRemoteContextSave: [NSDeletedObjectsKey: objectIDs], into: [self.backgroundContext])
// todo: does the background/view contexts need to get saved then?
}
let req = Item.fetchRequest()
req.predicate = NSPredicate(format: "id in %@", syncUpdate.upsert.map(\.id))
let existing = try self.backgroundContext.fetch(req)
self.logger.debug("syncItems: updating \(existing.count, privacy: .public) items, inserting \(syncUpdate.upsert.count - existing.count, privacy: .public)")
// todo: this feels like it'll be slow when there are many items
for item in syncUpdate.upsert {
if let existing = existing.first(where: { $0.id == item.id }) {
existing.updateFromServer(item)
} else {
let mo = Item(context: self.backgroundContext)
mo.updateFromServer(item)
}
}
if self.backgroundContext.hasChanges {
try self.backgroundContext.save()
}
}
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try await self.saveViewContext()
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}
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}