Prevent delay between mail addings and better folder init cancellation.

Wino.Core.Domain/Interfaces/IMailService.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Collections.Generic;
+using System.Threading;
 using System.Threading.Tasks;
-using MimeKit;
 using Wino.Core.Domain.Entities;
 using Wino.Core.Domain.Models.MailItem;
 
@@ -11,7 +11,7 @@ namespace Wino.Core.Domain.Interfaces
     {
         Task<MailCopy> GetSingleMailItemAsync(string mailCopyId, string remoteFolderId);
         Task<MailCopy> GetSingleMailItemAsync(Guid uniqueMailId);
-        Task<List<IMailItem>> FetchMailsAsync(MailListInitializationOptions options);
+        Task<List<IMailItem>> FetchMailsAsync(MailListInitializationOptions options, CancellationToken cancellationToken = default);
 
         /// <summary>
         /// Deletes all mail copies for all folders.

Wino.Core/Services/MailService.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Kiota.Abstractions.Extensions;
 using MimeKit;
@@ -193,7 +194,7 @@ namespace Wino.Core.Services
             return query.GetRawQuery();
         }
 
-        public async Task<List<IMailItem>> FetchMailsAsync(MailListInitializationOptions options)
+        public async Task<List<IMailItem>> FetchMailsAsync(MailListInitializationOptions options, CancellationToken cancellationToken = default)
         {
             var query = BuildMailFetchQuery(options);
 
@@ -216,6 +217,8 @@ namespace Wino.Core.Services
 
             if (!options.CreateThreads)
             {
+                cancellationToken.ThrowIfCancellationRequested();
+
                 // Threading is disabled. Just return everything as it is.
                 mails.Sort(options.SortingOptionType == SortingOptionType.ReceiveDate ? new DateComparer() : new NameComparer());
 
@@ -229,6 +232,8 @@ namespace Wino.Core.Services
             // Each account items must be threaded separately.
             foreach (var group in mails.GroupBy(a => a.AssignedAccount.Id))
             {
+                cancellationToken.ThrowIfCancellationRequested();
+
                 var accountId = group.Key;
                 var groupAccount = mails.First(a => a.AssignedAccount.Id == accountId).AssignedAccount;
 
@@ -242,6 +247,7 @@ namespace Wino.Core.Services
                 // Almost everything already should be in cache from initial population.
                 foreach (var mail in accountThreadedItems)
                 {
+                    cancellationToken.ThrowIfCancellationRequested();
                     await LoadAssignedPropertiesWithCacheAsync(mail, folderCache, accountCache).ConfigureAwait(false);
                 }
 
@@ -252,6 +258,7 @@ namespace Wino.Core.Services
             }
 
             threadedItems.Sort(options.SortingOptionType == SortingOptionType.ReceiveDate ? new DateComparer() : new NameComparer());
+            cancellationToken.ThrowIfCancellationRequested();
 
             return threadedItems;
 

Wino.Mail.ViewModels/MailListPageViewModel.cs

@@ -614,8 +614,6 @@ namespace Wino.Mail.ViewModels
 
             try
             {
-                await listManipulationSemepahore.WaitAsync();
-
                 if (ActiveFolder == null) return;
 
                 // At least accounts must match.
@@ -631,6 +629,8 @@ namespace Wino.Mail.ViewModels
                 // Item should be prevented from being added to the list due to filter.
                 if (!shouldPreventIgnoringFilter && ShouldPreventItemAdd(addedMail)) return;
 
+                await listManipulationSemepahore.WaitAsync();
+
                 await MailCollection.AddAsync(addedMail);
 
                 await ExecuteUIThread(() => { NotifyItemFoundState(); });
@@ -762,12 +762,17 @@ namespace Wino.Mail.ViewModels
                 // Folder is changed during initialization.
                 // Just cancel the existing one and wait for new initialization.
 
-                if (listManipulationSemepahore.CurrentCount == 0)
+                //if (listManipulationSemepahore.CurrentCount == 0)
-                {
+                //{
-                    Debug.WriteLine("Canceling initialization of mails.");
+                //    Debug.WriteLine("Canceling initialization of mails.");
 
+                //    listManipulationCancellationTokenSource.Cancel();
+                //    listManipulationCancellationTokenSource.Token.ThrowIfCancellationRequested();
+                //}
+
+                if (!listManipulationCancellationTokenSource.IsCancellationRequested)
+                {
                     listManipulationCancellationTokenSource.Cancel();
-                    listManipulationCancellationTokenSource.Token.ThrowIfCancellationRequested();
                 }
 
                 listManipulationCancellationTokenSource = new CancellationTokenSource();
@@ -794,15 +799,18 @@ namespace Wino.Mail.ViewModels
                                                                               SearchQuery,
                                                                               MailCollection.MailCopyIdHashSet);
 
-                var items = await _mailService.FetchMailsAsync(initializationOptions).ConfigureAwait(false);
+                var items = await _mailService.FetchMailsAsync(initializationOptions, cancellationToken).ConfigureAwait(false);
 
-                // Here they are already threaded if needed.
+                if (!listManipulationCancellationTokenSource.IsCancellationRequested)
-                // We don't need to insert them one by one.
+                {
-                // Just create VMs and do bulk insert.
+                    // Here they are already threaded if needed.
+                    // We don't need to insert them one by one.
+                    // Just create VMs and do bulk insert.
 
-                var viewModels = PrepareMailViewModels(items);
+                    var viewModels = PrepareMailViewModels(items);
 
-                await ExecuteUIThread(() => { MailCollection.AddRange(viewModels, true); });
+                    await ExecuteUIThread(() => { MailCollection.AddRange(viewModels, true); });
+                }
             }
             catch (OperationCanceledException)
             {