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Alternatives for Monitor (Wait, PluseAll) in Async Tasks in C#

I implemented Task synchronization using Monitor in C#.
However, I have read Monitor should not be used in asynchronous operation.
In the below code, how do I implement Monitor methods Wait and PulseAll with a construct that works with Task (asynchronous operations).
I have read that SemaphoreSlim.WaitAsync and Release methods can help.
But how do they fit in the below sample where multiple tasks need to wait on a lock object, and releasing the lock wakes up all waiting tasks ?
private bool m_condition = false;
private readonly Object m_lock = new Object();
private async Task<bool> SyncInteralWithPoolingAsync(
SyncDatabase db,
List<EntryUpdateInfo> updateList)
{
List<Task> activeTasks = new List<Task>();
int addedTasks = 0;
int removedTasks = 0;
foreach (EntryUpdateInfo entryUpdateInfo in updateList)
{
Monitor.Enter(m_lock);
//If 5 tasks are waiting in ProcessEntryAsync method
if(m_count >= 5)
{
//Do some batch processing to obtian values to set for adapterEntry.AdapterEntryId in ProcessEntryAsync
//.......
//.......
m_condition = true;
Monitor.PulseAll(m_lock); // Wakes all waiters AFTER lock is released
}
Monitor.Exit(m_lock);
removedTasks += activeTasks.RemoveAll(t => t.IsCompleted);
Task processingTask = Task.Run(
async () =>
{
await this.ProcessEntryAsync(
entryUpdateInfo,
db)
.ContinueWith(this.ProcessEntryCompleteAsync)
.ConfigureAwait(false);
});
activeTasks.Add(processingTask);
addedTasks++;
}
}
private async Task<bool> ProcessEntryAsync(SyncDatabase db, EntryUpdateInfo entryUpdateInfo)
{
SyncEntryAdapterData adapterEntry =
updateInfo.Entry.AdapterEntries.FirstOrDefault(e => e.AdapterId == this.Config.Id);
if (adapterEntry == null)
{
adapterEntry = new SyncEntryAdapterData()
{
SyncEntry = updateInfo.Entry,
AdapterId = this.Config.Id
};
updateInfo.Entry.AdapterEntries.Add(adapterEntry);
}
m_condition = false;
Monitor.Enter(m_lock);
while (!m_condition)
{
m_count++;
Monitor.Wait(m_lock);
}
m_count--;
adapterEntry.AdapterEntryId = .... //Set Value obtained form batch processing
Monitor.Exit(m_lock);
}
private void ProcessEntryCompleteAsync(Task<bool> task, object context)
{
EntryProcessingContext ctx = (EntryProcessingContext)context;
try
{
string message;
if (task.IsCanceled)
{
Logger.Warning("Processing was cancelled");
message = "The change was cancelled during processing";
}
else if (task.Exception != null)
{
Exception ex = task.Exception;
Logger.Warning("Processing failed with {0}: {1}", ex.GetType().FullName, ex.Message);
message = "An error occurred while synchronzing the changed.";
}
else
{
message = "The change was successfully synchronized";
if (task.Result)
{
//Processing
//...
//...
}
}
}
catch (Exception e)
{
Logger.Info(
"Caught an exception while completing entry processing. " + e);
}
finally
{
}
}
Thanks

How can I run many asynchronous methods all together?

I want to run my asynchronous methods GetPlayerCountryData() and GetPlayerTagsData() all together to save time instead of starting the next method only after the previous has completed. But I don't know how to do that.
https://jeremylindsayni.wordpress.com/2019/03/11/using-async-await-and-task-whenall-to-improve-the-overall-speed-of-your-c-code/
I have read this tutorial but I don't know how to use await Task.WhenAll() in my code.
In addition, I want to execute the line AllMethodsCompleted = true; after all my asynchronous methods have been completed successfully. Should I use await Task.WhenAll() in this situation?
How can I only set AllMethodsCompleted = true if all my asynchronous methods completed successfully? Is it possible to find out if (result.Error != null) or an exception occurred in one of the asynchronous methods before setting AllMethodsCompleted = true ?
string PlayerDeviceId = "";
private void RegisterGuestPlayFabAccount()
{
PlayerDeviceId = ReturnMobileID();
var requestIOS = new LoginWithIOSDeviceIDRequest { DeviceId = PlayerDeviceId, CreateAccount = true };
var loginTask = PlayFabClientAPI.LoginWithIOSDeviceIDAsync(requestIOS);
loginTask.ContinueWith(OnPlayFabRegisterGuestAccountComplete);
}
private void OnPlayFabRegisterGuestAccountComplete(Task<PlayFabResult<LoginResult>> task)
{
if (task.Result.Result != null)
{
PlayerAccountDetails();
}
if (task.Result.Error != null)
{
OnPlayFabError(task.Result.Error);
}
}
bool AllMethodsCompleted = false;
public async void PlayerAccountDetails()
{
await GetPlayerCountryData();
await GetPlayerTagsData();
AllMethodsCompleted = true;
}
private async Task GetPlayerTagsData()
{
var resultprofile = await PlayFabServerAPI.GetPlayerTagsAsync(new PlayFab.ServerModels.GetPlayerTagsRequest()
{
PlayFabId = PlayerPlayFabID
});
if (resultprofile.Error != null)
OnPlayFabError(result.Error);
else
{
if ((resultprofile.Result != null) && (resultprofile.Result.Tags.Count() > 0))
CurrentPlayerTag = resultprofile.Result.Tags[0].ToString();
}
}
private async Task GetPlayerCountryData()
{
var resultprofile = await PlayFabClientAPI.GetUserDataAsync(new PlayFab.ClientModels.GetUserDataRequest()
{
PlayFabId = PlayerPlayFabID,
Keys = null
});
if (resultprofile.Error != null)
OnPlayFabError(result.Error);
else
{
if (resultprofile.Result.Data == null || !resultprofile.Result.Data.ContainsKey("Country") || !resultprofile.Result.Data.ContainsKey("City"))
Console.WriteLine("No Country/City");
else
{
PlayerCountry = resultprofile.Result.Data["Country"].Value);
PlayerCity = resultprofile.Result.Data["City"].Value);
}
}
}

public async Task PlayerAccountDetails()
{
var playerCountryData = GetPlayerCountryData());
var playerTagsData = GetPlayerTagsData());
await Task.WhenAll(playerCountryData, playerTagsData);
AllMethodsCompleted = true;
}
Here is the method you are in query about and running the 2 methods in async waiting for each to finish then moving on. They just needed to be assigned to a task variable.

Correct way of starting a forever-running loop with Async

I've an existing code I wrote some time ago, that works but I dislike the fact that the thread I start remains in loop.
This piece of code is a consumer on an IBMMQ code, waiting for messages to be processed.The problem I've is that with the following code
private Task ExecuteQueuePolling(CancellationToken cancellationToken)
{
return Task.Factory.StartNew(() =>
{
ConnectToAccessQueue();
Logger.Debug($"Accessed to the queue {queueName}");
Logger.DebugFormat("Repeating timer started, checking frequency: {checkingFrequency}",
checkingFrequency);
while (!cancellationToken.IsCancellationRequested)
{
Logger.Trace( () => "Listening on queues for new messages");
// isChecking = true;
var mqMsg = new MQMessage();
var mqGetMsgOpts = new MQGetMessageOptions
{ WaitInterval = (int)checkingFrequency.TotalMilliseconds };
// 15 second limit for waiting
mqGetMsgOpts.Options |= MQC.MQGMO_WAIT | MQC.MQGMO_FAIL_IF_QUIESCING |
MQC.MQCNO_RECONNECT_Q_MGR | MQC.MQOO_INPUT_AS_Q_DEF;
try
{
mqQueue.Get(mqMsg, mqGetMsgOpts);
if (string.Compare(mqMsg.Format, MQC.MQFMT_STRING, StringComparison.Ordinal) == 0)
{
var text = mqMsg.ReadString(mqMsg.MessageLength);
Logger.Debug($"Message received : [{text}]");
Message message = new Message { Content = text };
foreach (var observer in observers)
observer.OnNext(message);
}
else
{
Logger.Warn("Non-text message");
}
}
catch (MQException ex)
{
if (ex.Message == MQC.MQRC_NO_MSG_AVAILABLE.ToString())
{
Logger.Trace("No messages available");
//nothing to do, emtpy queue
}
else if (ex.Message == MQC.MQRC_CONNECTION_BROKEN.ToString())
{
Logger.ErrorException("MQ Exception, trying to recconect", ex);
throw new ReconnectException();
}
}
Thread.Sleep(100);
}
},cancellationToken);
}
//Calling method
try
{
string queueManagerName = configuration.GetValue<string>("IBMMQ:QUEUE_MANAGER_NAME");
// var queueManager = new MQQueueManager(queueManagerName,dictionary2);
QueueMonitor monitor = new QueueMonitor(configuration, "IMPORTER_RECEIVER_TEST");
//_subscription = monitor.Subscribe(receiver);
await monitor.StartAsync(cts.Token).ConfigureAwait(false);
}
catch (Exception e)
{
log.Error(e, "Error creating the queue monitor or it's subscription");
}
finally
{
WaitForCancel(cts);
}
The call to await monitor.StartAsync(cts.Token).ConfigureAwait(false); remains pending.
How should I modify my code, so that the call returns and in background the task continue to loop?
Thanks in advance

Here is how you can simplify your code by replacing Thread.Sleep with Task.Delay:
private async Task ExecuteQueuePolling(CancellationToken cancellationToken)
{
while (true)
{
// Process mqQueue here
await Task.Delay(100, cancellationToken);
}
}
Task.Delay has the advantage that accepts a CancellationToken, so in case of cancellation the loop will exit immediately. This could be important if the pooling of the MQ was lazier (for example every 5 seconds).

private static Task _runningTask;
static void Main(string[] args)
{
var cts = new CancellationTokenSource();
_runningTask = ExecuteQueuePolling(cts.Token);
WaitForCancel(cts);
}
private static void WaitForCancel(CancellationTokenSource cts)
{
var spinner = new SpinWait();
while (!cts.IsCancellationRequested
&& _runningTask.Status == TaskStatus.Running) spinner.SpinOnce();
}
private static Task ExecuteQueuePolling(CancellationToken cancellationToken)
{
var t = new Task(() =>
{
while (!cancellationToken.IsCancellationRequested)
; // your code
if (cancellationToken.IsCancellationRequested)
throw new OperationCanceledException();
}, cancellationToken, TaskCreationOptions.LongRunning);
t.Start();
return t;
}

Blocking UI thread dosen't render UI components of an other window

In my application I have a scenario where I need to block the UI Thread when I perform an action. While its blocked I have an other window that needs to show a message saying "performing action please wait" when the UI is blocked. Problem is the window shows up but it never displays the message. Please help. Even DoEvents() dosen't help. It just so lightly displays the message
Note:
I don't want the method as async because I want to block the UI when it runs.
I don't want to say ShowDialog() because it just blocks there.
private void ViewModel_PerformPrimeAction(InstrumentAction Action)
{
bool abort = false;
CommandRunningWindow cmdDialog = null;
if (Action == InstrumentAction.Prime)
{
if (Xceed.Wpf.Toolkit.MessageBox.Show((string)TryFindResource("ConfirmPrimeInstrument"),
ApplicationSettingsViewModel.Instance.ProductName, MessageBoxButton.YesNo, MessageBoxImage.Question) != MessageBoxResult.Yes)
return;
this.IsEnabled = false;
//This below line never shows the message.
cmdDialog = ShowCommandWindow(ViewModelsHelper.GetResourceString("PerformingPrime"));
System.Windows.Forms.Application.DoEvents();
}
UIUtils.OverrideCursor = System.Windows.Input.Cursors.Wait;
try
{
// This operation takes 10 seconds
QXInstrumentViewModel.Instance.Prime(() => { if (abort) throw new RunAbortedException(null); });
}
catch (RunAbortedException)
{
errorMessage = (string)TryFindResource("CompletePrimeInstrumentAborted");
cmdDialog?.Close();
}
catch (Exception ex)
{
var message = QXInstrumentViewModel.ToErrorCode(ex);
TokenSource = new System.Threading.CancellationToken(true);
if (message != null)
{
errorMessage = string.Format((string)TryFindResource("CompletePrimeInstrumentWithError"), Convert.ToInt32(message), errorMessage);
}
else
{
errorMessage = (string)TryFindResource("CompletePrimeInstrumentWithUnknownError");
}
cmdDialog?.Close();
}
UIUtils.OverrideCursor = null;
this.IsEnabled = true;
}
public CommandRunningWindow ShowCommandWindow(string message)
{
CommandRunningWindow cmdDialog = new CommandRunningWindow();
cmdDialog.Message = message;
cmdDialog.Owner = WPFUtils.GetActiveWindow();
cmdDialog.Show();
return cmdDialog;
}
The CommandRunningWindow has a dependency property of type string (message) that is bound to a textblock.

You can't both block and show a message on the same thread simultaneously.
What you should do is to execute your long-running operation on a background thread - the easiest way to do this is to start a TPL task - and display the message on the UI thread. You may still disable the window. Just make sure that you don't touch the UI on the background thread where your long-running operation executes.
private void ViewModel_PerformPrimeAction(InstrumentAction Action)
{
bool abort = false;
CommandRunningWindow cmdDialog = null;
if (Action == InstrumentAction.Prime)
{
if (Xceed.Wpf.Toolkit.MessageBox.Show((string)TryFindResource("ConfirmPrimeInstrument"),
ApplicationSettingsViewModel.Instance.ProductName, MessageBoxButton.YesNo, MessageBoxImage.Question) != MessageBoxResult.Yes)
return;
this.IsEnabled = false;
//This below line never shows the message.
cmdDialog = ShowCommandWindow(ViewModelsHelper.GetResourceString("PerformingPrime"));
}
UIUtils.OverrideCursor = System.Windows.Input.Cursors.Wait;
Task.Factory.StartNew(() =>
{
// This operation takes 10 seconds
QXInstrumentViewModel.Instance.Prime(() => { if (abort) throw new RunAbortedException(null); });
})
.ContinueWith(task =>
{
if (task.IsFaulted)
{
if (task.Exception != null && task.Exception.GetBaseException() is RunAbortedException)
{
var message = QXInstrumentViewModel.ToErrorCode(ex);
TokenSource = new System.Threading.CancellationToken(true);
if (message != null)
{
errorMessage = string.Format((string)TryFindResource("CompletePrimeInstrumentWithError"), Convert.ToInt32(message), errorMessage);
}
else
{
errorMessage = (string)TryFindResource("CompletePrimeInstrumentWithUnknownError");
}
}
else
{
errorMessage = (string)TryFindResource("CompletePrimeInstrumentAborted");
}
}
cmdDialog?.Close();
UIUtils.OverrideCursor = null;
this.IsEnabled = true;
}, System.Threading.CancellationToken.None, TaskContinuationOptions.None, TaskScheduler.FromCurrentSynchronizationContext());
}

UI Frozen / Tried to work with task / async await

I write a WPF Programm which reads the configuration of the PC.
The Programm has to be refreshed an the HttpWebRequest will delay the code so the UI will freez.
I tried to work with async / await tasks.
Method in Class Network:
public TreeView CreatTVURLs()
{
TreeView TVURLs = new TreeView(); //Here it will break. Says no STA-Thread
List<CPingables> lURLs = new List<CPingables>();
lURLs = ReadURLsFromFile();
TVURLs.Name = "URLs";
TVURLs.Background = System.Windows.Media.Brushes.Transparent;
TVURLs.BorderThickness = new Thickness(0);
foreach (CPingables item in lURLs)
{
tviURL.Items.Add("IP:\t\t\t" + item.IP.ToString());
tviURL.Items.Add("URL:\t\t\t" + item.URL);
... more stuff
Tried with Thread:
Code in MainWindow:
public async void openWindow()
{
TreeView tvURLs = new TreeView();
tvURLs = (TreeView) TreeViewTest();
//tvURLs = Network.CreatTVURLs();
StackPanel.Children.Add(tvURLs);
}
private TreeView TreeViewTest()
{
TreeView tvURLs = new TreeView();
Thread t = new Thread(() => { tvURLs = Network.CreatTVURLs(); });
t.SetApartmentState(ApartmentState.STA);
t.Start();
t.Join();
return tvURLs;
}
Tried with Task:
public async void openWindow()
{
TreeView tvURLs = new TreeView();
tvURLs = (TreeView) await TreeViewTest();
Task.WaitAll();
StackPanel.Children.Add(tvURLs);
}
private Task<TreeView> TreeViewTest()
{
TreeView tv = new TreeView();
return Task.Factory.StartNew(() => { tv=(TreeView)Network.CreatTVURLs()});
}
I get always says it must me a STA Thread to handle Formitems.
Edit:
HttpWebRequest
public async void pingIP()
{
try
{
if (_IPPingAvailible == true)
{
Ping pinger = new Ping();
PingReply replyIP = pinger.Send(_IP);
_PingByIP = replyIP.Status == IPStatus.Success;
}
}
catch (Exception)
{
_PingByIP = false;
}
try
{
if (_UrlAvailible == true)
{
var uriBuilder = new UriBuilder(_URL);
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uriBuilder.Uri);
request.Timeout = 1000;
using (var response = await request.GetResponseAsync() as HttpWebResponse)
{
if (response != null && response.StatusCode == HttpStatusCode.OK)
{
_ReachableByHttp = true;
}
else
{
_ReachableByHttp = false;
}
}
}
}
catch
{
_ReachableByHttp = false;
}
}

The rule is, that you can access UI elements only in UI thread (called also Dispatcher thread, or main thread). You are breaking this rule. You have cerate new thread by:
Task.Factory.StartNew(...) resp by new Thread(...);, but you are manipulating the UI elements (treeview) inside the new thread.
Instead, you should perform only the I/O operation or HttpRequest/Response in the new thread, but everything else (e.g. creating treeview from the http response data) should be done in UI thread.
public async void openWindow()
{
TreeView tvURLs = await Network.CreatTVURLsAsync();
StackPanel.Children.Add(tvURLs);
}
public async Task<TreeView> CreatTVURLsAsync()
{
//you are in dispatcher thread here, so you can access UI elements here
TreeView TVURLs = new TreeView();
TVURLs.Name = "URLs";
TVURLs.Background = System.Windows.Media.Brushes.Transparent;
TVURLs.BorderThickness = new Thickness(0);
List<CPingables> lURLs = null;
await Task.Run(() =>
{
//you are in new thread now, so you cannot access UI elements here
lURL = ReadURLsFromFile();
});
//you are in dispatcher thread again, so you can access UI elements again
foreach (CPingables item in lURLs)
{
var tviURL = new TreeViewItem();
..more stuff
TVURLs.Items.Add(tviURL);
}
}