feat: make sure refreshing folder task is not killed randomly in background

Mail/Views/Menu Drawer/FolderListView.swift

@@ -56,7 +56,7 @@ struct NestableFolder: Identifiable {
     }
 }
 
-class FolderListViewModel: ObservableObject {
+final class FolderListViewModel: ObservableObject {
     /// Special folders (eg. Inbox) for the current mailbox
     @Published var roleFolders = [NestableFolder]()
     /// User created folders for the current mailbox

Mail/Views/SplitView.swift

@@ -107,7 +107,7 @@ struct SplitView: View {
         .onChange(of: scenePhase) { newScenePhase in
             guard newScenePhase == .active else { return }
             Task {
-                async let _ = try? mailboxManager.folders()
+                async let _ = try? mailboxManager.refreshAllFolders()
                 async let _ = try? mailboxManager.refreshAllSignatures()
             }
         }
@@ -202,7 +202,7 @@ struct SplitView: View {
 
     private func fetchFolders() async {
         await tryOrDisplayError {
-            try await mailboxManager.folders()
+            try await mailboxManager.refreshAllFolders()
         }
     }
 

Mail/Views/Thread List/ThreadListViewModel.swift

@@ -201,7 +201,7 @@ final class DateSection: Identifiable, Equatable {
             isLoadingPage = true
         }
 
-        await mailboxManager.refresh(folder: folder.freezeIfNeeded())
+        await mailboxManager.refreshFolderContent(folder.freezeIfNeeded())
 
         withAnimation {
             isLoadingPage = false

MailCore/Cache/DraftManager.swift

@@ -255,7 +255,7 @@ public final class DraftManager {
 
     private func refreshDraftFolder(latestSendDate: Date?, mailboxManager: MailboxManager) async throws {
         if let draftFolder = mailboxManager.getFolder(with: .draft)?.freeze() {
-            await mailboxManager.refresh(folder: draftFolder)
+            await mailboxManager.refreshFolderContent(draftFolder)
 
             if let latestSendDate {
                 /*
@@ -264,7 +264,7 @@ public final class DraftManager {
                  */
                 let delay = latestSendDate.timeIntervalSinceNow
                 try await Task.sleep(nanoseconds: UInt64(1_000_000_000 * max(Double(delay), 1.5)))
-                await mailboxManager.refresh(folder: draftFolder)
+                await mailboxManager.refreshFolderContent(draftFolder)
             }
 
             await mailboxManager.deleteOrphanDrafts()
@@ -278,7 +278,7 @@ public final class DraftManager {
                     try await mailboxManager.delete(draft: liveDraft.freeze())
                     alertDisplayable.show(message: MailResourcesStrings.Localizable.snackbarDraftDeleted)
                     if let draftFolder = mailboxManager.getFolder(with: .draft)?.freeze() {
-                        await mailboxManager.refresh(folder: draftFolder)
+                        await mailboxManager.refreshFolderContent(draftFolder)
                     }
                 }
             }

MailCore/Cache/MailboxManager/MailboxManager+Folders.swift

@@ -18,16 +18,21 @@
 
 import Foundation
 import InfomaniakCore
+import InfomaniakCoreUI
 import RealmSwift
 
 // MARK: - Folders
 
 public extension MailboxManager {
-    func folders() async throws {
-        // Get from Realm
+    /// Get all remote folders in DB
+    func refreshAllFolders() async throws {
+        let backgroundTracker = await ApplicationBackgroundTaskTracker(identifier: #function + UUID().uuidString)
+
+        // Network check
         guard ReachabilityListener.instance.currentStatus != .offline else {
             return
         }
+
         // Get from API
         let folderResult = try await apiFetcher.folders(mailbox: mailbox)
         let newFolders = getSubFolders(from: folderResult)
@@ -37,12 +42,12 @@ public extension MailboxManager {
                 self.keepCacheAttributes(for: folder, using: realm)
             }
 
+            // Get from Realm
             let cachedFolders = realm.objects(Folder.self)
 
             // Update folders in Realm
             try? realm.safeWrite {
                 // Remove old folders
-                realm.add(folderResult, update: .modified)
                 let toDeleteFolders = Set(cachedFolders).subtracting(Set(newFolders)).filter { $0.id != Constants.searchFolderId }
                 var toDeleteThreads = [Thread]()
 
@@ -59,8 +64,13 @@ public extension MailboxManager {
                 realm.delete(toDeleteMessages)
                 realm.delete(toDeleteThreads)
                 realm.delete(toDeleteFolders)
+
+                // Insert fresh remote folders
+                realm.add(folderResult, update: .modified)
             }
         }
+
+        await backgroundTracker.end()
     }
 
     /// Get the folder with the corresponding role in Realm.
@@ -106,8 +116,8 @@ public extension MailboxManager {
         try await refreshActor.refreshFolder(from: messages, additionalFolder: additionalFolder)
     }
 
-    func refresh(folder: Folder) async {
-        await refreshActor.refresh(folder: folder)
+    func refreshFolderContent(_ folder: Folder) async {
+        await refreshActor.refreshFolderContent(folder)
     }
 
     func cancelRefresh() async {

MailCore/Cache/RefreshActor.swift

@@ -17,6 +17,7 @@
  */
 
 import Foundation
+import InfomaniakCoreUI
 
 public actor RefreshActor {
     weak var mailboxManager: MailboxManager?
@@ -29,25 +30,41 @@ public actor RefreshActor {
 
     public func flushFolder(folder: Folder, mailbox: Mailbox, apiFetcher: MailApiFetcher) async throws -> Bool {
         let response = try await apiFetcher.flushFolder(mailbox: mailbox, folderId: folder.id)
-        await refresh(folder: folder)
+        await refreshFolderContent(folder)
         return response
     }
 
     public func refreshFolder(from messages: [Message], additionalFolder: Folder?) async throws {
-        var folders = messages.map(\.folder)
-        if let additionalFolder {
-            folders.append(additionalFolder)
+        let updateFolders = Task {
+            var folders = messages.map(\.folder)
+            if let additionalFolder {
+                folders.append(additionalFolder)
+            }
+
+            let orderedSet = NSOrderedSet(array: folders as [Any])
+
+            for folder in orderedSet {
+                guard !Task.isCancelled else { break }
+                guard let impactedFolder = folder as? Folder else { continue }
+                await refreshFolderContent(impactedFolder)
+            }
         }
 
-        let orderedSet = NSOrderedSet(array: folders as [Any])
+        // Track progress in background with a cancelation handler
+        let backgroundTracker = await ApplicationBackgroundTaskTracker(identifier: #function + UUID().uuidString) {
+            updateFolders.cancel()
 
-        for folder in orderedSet {
-            guard let impactedFolder = folder as? Folder else { continue }
-            await refresh(folder: impactedFolder)
+            Task {
+                await self.cancelRefresh()
+            }
         }
+
+        await updateFolders.finish()
+
+        await backgroundTracker.end()
     }
 
-    public func refresh(folder: Folder) async {
+    public func refreshFolderContent(_ folder: Folder) async {
         await cancelRefresh()
 
         refreshTask = Task {

MailNotificationServiceExtension/NotificationService.swift

@@ -47,7 +47,7 @@ final class NotificationService: UNNotificationServiceExtension {
             // We do nothing if we don't have an initial cursor
             return nil
         }
-        await mailboxManager.refresh(folder: inboxFolder.freezeIfNeeded())
+        await mailboxManager.refreshFolderContent(inboxFolder.freezeIfNeeded())
 
         @ThreadSafe var message = mailboxManager.getRealm().object(ofType: Message.self, forPrimaryKey: uid)
 

MailTests/MailboxManagerTests.swift

@@ -44,7 +44,7 @@ final class MailboxManagerTests: XCTestCase {
     // MARK: Tests methods
 
     func testFolders() async throws {
-        try await MailboxManagerTests.mailboxManager.folders()
+        try await MailboxManagerTests.mailboxManager.refreshAllFolders()
     }
 
     func testThreads() async throws {