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How to get status of long running task

Why does the Status of my Task return "WaitingForActivasion" instead of "Running" ?
If I remove Task.Run I get stuck in the while loop, so I assume its not running asynchronous.
public class StateManagerTest
{
[Fact]
public void Start_TaskStatus()
{
StateManager manager = new StateManager();
manager.Start();
Assert.True(manager.Status == System.Threading.Tasks.TaskStatus.Running.ToString());
}
}
public class StateManager
{
private CancellationTokenSource cts = new();
private Task updateTask;
public HashSet<StateItem> StateItems { get; private set; }
public Provider Provider { get; private set; }
public List<OutputService> OutputServices { get; private set; }
public string Status
{
get => updateTask.Status.ToString();
}
public StateManager()
{
StateItems = new();
OutputServices = new();
Provider = new();
}
public void Stop()
{
cts.Cancel();
}
public void Start()
{
updateTask = Task.Run(() => Update(cts.Token))
.ContinueWith(t => Debug.WriteLine(t.Exception.Message), TaskContinuationOptions.OnlyOnFaulted);
}
private async Task Update(CancellationToken token)
{
while (true)
{
// get changes from outputs
Dictionary<StateItem, object> changes = new Dictionary<StateItem, object>();
foreach (var service in OutputServices)
{
var outputChanges = await service.GetChanges();
foreach (var change in outputChanges)
changes.TryAdd(change.Key, change.Value);
}
// write changes to provider source
await Provider.PushChanges(changes);
// update state
await Provider.UpdateStateItems();
// update all services
foreach (var service in OutputServices)
await service.UpdateSource();
if (token.IsCancellationRequested)
return;
}
}
}

As others have noted, WaitingForActivation is the correct state for a Promise Task that is not yet completed. In general, I recommend not using Task.Status or ContinueWith; they are relics from a time before async/await existed.
How to get status of long running task
I believe you would want progress reporting, which is done yourself. The T in IProgress<T> can be a string if you want a simple text update, or a double if you want a percentage update, or a custom struct if you want a more complex update.

.net core - Passing an unknown number of IProgress<T> to class library

I have a console app which uses a class library to execute some long running tasks. This is a .net core console app and uses the .net core Generic Host. I also use the ShellProgressBar library to display some progress bars.
My Hosted service looks like this
internal class MyHostedService : IHostedService, IDisposable
{
private readonly ILogger _logger;
private readonly IMyService _myService;
private readonly IProgress<MyCustomProgress> _progress;
private readonly IApplicationLifetime _appLifetime;
private readonly ProgressBar _progressBar;
private readonly IProgressBarFactory _progressBarFactory;
public MyHostedService(
ILogger<MyHostedService> logger,
IMyService myService,
IProgressBarFactory progressBarFactory,
IApplicationLifetime appLifetime)
{
_logger = logger;
_myService = myService;
_appLifetime = appLifetime;
_progressBarFactory = progressBarFactory;
_progressBar = _progressBarFactory.GetProgressBar(); // this just returns an instance of ShellProgressBar
_progress = new Progress<MyCustomProgress>(progress =>
{
_progressBar.Tick(progress.Current);
});
}
public void Dispose()
{
_progressBar.Dispose();
}
public Task StartAsync(CancellationToken cancellationToken)
{
_myService.RunJobs(_progress);
_appLifetime.StopApplication();
return Task.CompletedTask;
}
public Task StopAsync(CancellationToken cancellationToken)
{
return Task.CompletedTask;
}
}
Where MyCustomProgress looks like this
public class MyCustomProgress
{
public int Current {get; set;}
public int Total {get; set;}
}
and MyService looks something like so (Job1, Job2, Job3 implement IJob)
public class MyService : IMyService
{
private void List<IJob> _jobsToRun;
public MyService()
{
_jobsToRun.Add(new Job1());
_jobsToRun.Add(new Job2());
_jobsToRun.Add(new Job3());
}
public void RunJobs(IProgress<MyCustomProgress> progress)
{
_jobsToRun.ForEach(job =>
{
job.Execute();
progress.Report(new MyCustomProgress { Current = _jobsToRun.IndexOf(job) + 1, Total = _jobsToRun.Count() });
});
}
}
And IJob is
public interface IJob
{
void Execute();
}
This setup works well and I'm able to display the progress bar from my HostedService by creating a ShellProgressBar instance and using the one IProgress instance I have to update it.
However, I have another implementation of IMyService that I also need to run that looks something like this
public class MyService2 : IMyService
{
private void List<IJob> _sequentialJobsToRun;
private void List<IJob> _parallelJobsToRun;
public MyService()
{
_sequentialJobsToRun.Add(new Job1());
_sequentialJobsToRun.Add(new Job2());
_sequentialJobsToRun.Add(new Job3());
_parallelJobsToRun.Add(new Job4());
_parallelJobsToRun.Add(new Job5());
_parallelJobsToRun.Add(new Job6());
}
public void RunJobs(IProgress<MyCustomProgress> progress)
{
_sequentialJobsToRun.ForEach(job =>
{
job.Execute();
progress.Report(new MyCustomProgress { Current = _jobsToRun.IndexOf(job) + 1, Total = _jobsToRun.Count() });
});
Parallel.ForEach(_parallelJobsToRun, job =>
{
job.Execute();
// Report progress here
});
}
}
This is the one I'm struggling with. when _parallelJobsToRun is executed, I need to be able to create a new child ShellProgressBar (ShellProgressBar.Spawn) and display them as child progress bars of let's say 'Parallel Jobs'.
This is where I'm looking for some help as to how I can achieve this.
Note: I don't want to take a dependency on ShellProgressBar in my class library containing MyService
Any help much appreciated.

I am a little confused by your description, but let's see if I understand what you are up to. So if you wrap all of this in a class, then taskList1 and taskList2 could be class variables. (By the way taskList1/2 should be named better: say parallelTaskList and whatever . . . anyway.) Then you could write a new method on the class CheckTaskStatus() and just iterate over the two class variables. Does that help or have I completely missed your question?

Can you modify it like this?
public Task<ICollection<IProgress<int>>> StartAsync(CancellationToken cancellationToken)
{
var progressList = _myServiceFromLibrary.RunTasks();
return Task.FromResult(progressList);
}
public ICollection<IProgress<int>> RunTasks()
{
var taskList1 = new List<ITask> { Task1, Task2 };
var plist1 = taskList1.Select(t => t.Progress).ToList();
var taskList2 = new List<ITask> { Task3, Task4, Task5 }:
var plist2 = taskList2.Select(t => t.Progress).ToList();
taskList1.foreach( task => task.Run() );
Parallel.Foreach(taskList2, task => { task.Run() });
return plist1.Concat(plist2).ToList();
}
Task.Progress there is probably a progress getter. realistically IProgress should probably be injected via Tasks constructors. But the point is your public interface doesn't accept list of tasks, thus it should just return collection of progress reports.
How to inject progress reporters into your tasks is a different story that depends on tasks implementations and it may or may not be supported. out of the box.
However what you probably should do is to supply progress callback or progress factory so that progress reporters of your choice are created:
public Task StartAsync(CancellationToken cancellationToken, Action<Task,int> onprogress)
{
_myServiceFromLibrary.RunTasks(onprogress);
return Task.CompletedTask;
}
public class SimpleProgress : IProgress<int>
{
private readonly Task task;
private readonly Action<Task,int> action;
public SimpleProgress(Task task, Action<Task,int> action)
{
this.task = task;
this.action = action;
}
public void Report(int progress)
{
action(task, progress);
}
}
public ICollection<IProgress<int>> RunTasks(Action<Task,int> onprogress)
{
var taskList1 = new List<ITask> { Task1, Task2 };
taskList1.foreach(t => t.Progress = new SimpleProgress(t, onprogress));
var taskList2 = new List<ITask> { Task3, Task4, Task5 }:
taskList2.foreach(t => t.Progress = new SimpleProgress(t, onprogress));
taskList1.foreach( task => task.Run() );
Parallel.Foreach(taskList2, task => { task.Run() });
}
you may see here, that it really is mostly question about how your tasks are going to call IProgress<T>.Report(T value) method.

Honestly I would just use an event in your task prototype.
It's not really clear exactly what you want because the code you posted doesn't match the names you then reference in your question text... It would be helpful to have all the code (the RunTasks function for example, your IProgress prototype, etc).
Nevertheless, an event exists specifically to signal calling code. Let's go back to the basics. Let's say you have library called MyLib, with a method DoThings().
Create a new class that inherits from EventArgs, and that will carry your task's progress reports...
public class ProgressEventArgs : EventArgs
{
private int _taskId;
private int _percent;
private string _message;
public int TaskId => _taskId;
public int Percent => _percent;
public string Message => _message;
public ProgressEventArgs(int taskId, int percent, string message)
{
_taskId = taskId;
_percent = percent;
_message = message;
}
}
Then on your library's class definition, add an event like so:
public event EventHandler<ProgressEventArgs> Progress;
And in your console application, create a handler for progress events:
void ProgressHandler(object sender, ProgressEventArgs e)
{
// Do whatever you want with your progress report here, all your
// info is in the e variable
}
And subscribe to your class library's event:
var lib = new MyLib();
lib.Progress += ProgressHandler;
lib.DoThings();
When you are done, unsubscribe from the event:
lib.Progress -= ProgressHandler;
In your class library, now you can send back progress reports by raising the event in your code. First create a stub method to invoke the event:
protected virtual void OnProgress(ProgressEventArgs e)
{
var handler = Progress;
if (handler != null)
{
handler(this, e);
}
}
And then add this to your task's code where you want it:
OnProgress(new ProgressEventArgs(2452343, 10, "Reindexing google..."));
The only thing to be careful about is to report progress sparingly, because each time your event fires it interrupts your console application, and you can really bog it down hard if you send 10 million events all at once. Be logical about it.

Alternate way; If you own the code IProgress<T> and Progress
IProgress<T>
{
IProgress<T> CreateNew();
Report(T progress);
}
Progress<T> : IProgress<T>
{
Progress(ShellProgressClass)
{
// initialize progressBar or span new
}
....
IProgress<T> CreateNew()
{
return new Progress();
}
}
you can later improvise to have one big progressBar (collection of Sequential or Parallel) and what not

Your MyService could have a dependency similar to:
public interface IJobContainer
{
void Add(IJob job);
void RunJobs(IProgress<MyProgress> progress, Action<IJob>? callback = null); // Using an action for extra work you may want to do
}
This way you don't have to worry about reporting progress in MyService (which doesn't feel like it should be MyService's job anyway. The implementation could look something like this for the parallel job container:
public class MyParallelJobContainer
{
private readonly IList<IJob> parallelJobs = new List<IJob>();
public MyParallelJobContainer()
{
this.progress = progress;
}
public void Add(IJob job) { ... }
void RunJobs(IProgress<MyProgress> progress, Action<IJob>? callback = null)
{
using (var progressBar = new ProgressBar(options...))
{
Parallel.ForEach(parallelJobs, job =>
{
callback?.Invoke(job);
job.Execute();
progressBar.Tick();
})
}
}
}
MyService would then look like this:
public class MyService : IMyService
{
private readonly IJobContainer sequentialJobs;
private readonly IJobContainer parallelJobs;
public MyService(
IJobContainer sequentialJobs,
IJobContainer parallelJobs)
{
this.sequentialJobs = sequentialJobs;
this.parallelJobs = parallelJobs;
this.sequentialJobs.Add(new DoSequentialJob1());
this.sequentialJobs.Add(new DoSequentialJob2());
this.sequentialJobs.Add(new DoSequentialJob3));
this.parallelJobs.Add(new DoParallelJobA());
this.parallelJobs.Add(new DoParallelJobB());
this.parallelJobs.Add(new DoParallelJobC());
}
public void RunJobs(IProgress<MyCustomProgress> progress)
{
sequentialJobs.RunJobs(progress, job =>
{
// do something with the job if necessary
});
parallelJobs.RunJobs(progress, job =>
{
// do something with the job if necessary
});
}
The advantage of this way is that MyService only has one job and doesn't have to worry about what you do once the job is completed.

From my understanding of your issue the question is how do you display progress across both completion of the synchronous jobs and parallelized jobs.
In theory the parallel jobs could start and finish at the same time, so you could treat the parallel jobs as a single job. Instead of using the count of sequential jobs as your total, increase that number by one. This might be satisfactory for a small number of parallel jobs.
If you want to add progress between the parallel jobs, you will need to handle multi-threading in your code because the parallel jobs will be running concurrently.
object pJobLock = new object();
int numProcessed = 0;
foreach(var parallelJob in parallelJobs)
{
parallelJob.DoWork();
lock (pJobLock)
{
numProcessed++;
progress.Report(new MyCustomProgress { Current = numProcessed, Total = parallelJobs.Count() });
}
}

Timing issue between async initialisation and results loading in application startup

Seeking some input on a behaviour I'm noticing in my code below. This is my first attempt at async/await using Xamarin Forms and I have perused hundreds of posts, blogs and articles on the subject including the writings from Stephen Cleary on async from constructors and best practices to avoid locking. Although I am using a MVVM framework I assume my issue is more generic than that so I'll ignore it for the moment here.
If I am still missing something or there are ways to improve what I'm trying to do ... happy to listen and learn.
At a high level the logic is as follows:
Application starts and initialises
During initialisation verify database exist and if not - create the SQLite DB. Currently I force this every time to simulate a new application and pre-populate it with some sample data for development purposes
After initialisation completed load results set and display
This works most of the time but I have noticed 2 infrequent occurrences due to the async handling of the database initialisation and pre-populating:
Occasionally not all sample records created are displayed once the app started up - I assume this is because the pre-population phase has not completed when the results are loaded
Occasionally I get an error that one of the tables have not been created - I assume this is because the database initialisation has not completed when the results are loaded
The code - simplified to show the flow during initialisation and startup:
----------- VIEW / PAGE MODEL ----------------
public class MyListItemsPageModel
{
private ObservableRangeCollection<MyListItem> _myListItems;
private Command loadItemsCommand;
public MyListItemsPageModel()
{
_myListItems = new ObservableRangeCollection<MyListItem>();
}
public override void Init(object initData)
{
if (LoadItemsCommand.CanExecute(null))
LoadItemsCommand.Execute(null);
}
public Command LoadItemsCommand
{
get
{
return loadItemsCommand ?? (loadItemsCommand = new Command(async () => await ExecuteLoadItemsAsyncCommand(), () => { return !IsBusy; }));
}
}
public ObservableRangeCollection<MyListItem> MyListItems {
get { return _myListItems ?? (_myListItems = new ObservableRangeCollection<MyListItem>()); }
private set {
_myListItems = value;
}
}
private async Task ExecuteLoadItemsAsyncCommand() {
if (IsBusy)
return;
IsBusy = true;
loadItemsCommand.ChangeCanExecute();
var _results = await MySpecificDBServiceClass.LoadAllItemsAsync;
MyListItems = new ObservableRangeCollection<MyListItem>(_results.OrderBy(x => x.ItemName).ToList());
IsBusy = false;
loadItemsCommand.ChangeCanExecute();
}
}
----------- DB Service Class ----------------
// THERE IS A SPECIFIC SERVICE LAYER BETWEEN THIS CLASS AND THE PAGE VIEW MODEL HANDLING THE CASTING OF TO THE SPECIFIC DATA TYPE
// public class MySpecificDBServiceClass : MyGenericDBServiceClass
public class MyGenericDBServiceClass<T>: IDataAccessService<T> where T : class, IDataModel, new()
{
public SQLiteAsyncConnection _connection = FreshIOC.Container.Resolve<ISQLiteFactory>().CreateConnection();
internal static readonly AsyncLock Mutex = new AsyncLock();
public DataServiceBase()
{
// removed this from the constructor
//if (_connection != null)
//{
// IsInitialized = DatabaseManager.CreateTableAsync(_connection);
//}
}
public Task<bool> IsInitialized { get; private set; }
public virtual async Task<List<T>> LoadAllItemsAsync()
{
// Temporary async/await initialisation code. This will be moved to the start up as per Stephen's suggestion
await DBInitialiser();
var itemList = new List<T>();
using (await Mutex.LockAsync().ConfigureAwait(false))
{
itemList = await _connection.Table<T>().ToListAsync().ConfigureAwait(false);
}
return itemList;
}
}
----------- DB Manager Class ----------------
public class DatabaseManager
{
static double CURRENT_DATABASE_VERSION = 0.0;
static readonly AsyncLock Mutex = new AsyncLock();
private static bool IsDBInitialised = false;
private DatabaseManager() { }
public static async Task<bool> CreateTableAsync(SQLiteAsyncConnection CurrentConnection)
{
if (CurrentConnection == null || IsDBInitialised)
return IsDBInitialised;
await ProcessDBScripts(CurrentConnection);
return IsDBInitialised;
}
private static async Task ProcessDBScripts(SQLiteAsyncConnection CurrentConnection)
{
using (await Mutex.LockAsync().ConfigureAwait(false))
{
var _tasks = new List<Task>();
if (CURRENT_DATABASE_VERSION <= 0.1) // Dev DB - recreate everytime
{
_tasks.Add(CurrentConnection.DropTableAsync<Table1>());
_tasks.Add(CurrentConnection.DropTableAsync<Table2>());
await Task.WhenAll(_tasks).ConfigureAwait(false);
}
_tasks.Clear();
_tasks.Add(CurrentConnection.CreateTableAsync<Table1>());
_tasks.Add(CurrentConnection.CreateTableAsync<Table2>());
await Task.WhenAll(_tasks).ConfigureAwait(false);
_tasks.Clear();
_tasks.Add(UpgradeDBIfRequired(CurrentConnection));
await Task.WhenAll(_tasks).ConfigureAwait(false);
}
IsDBInitialised = true;
}
private static async Task UpgradeDBIfRequired(SQLiteAsyncConnection _connection)
{
await CreateSampleData();
return;
// ... rest of code not relevant at the moment
}
private static async Task CreateSampleData()
{
IDataAccessService<MyListItem> _dataService = FreshIOC.Container.Resolve<IDataAccessService<MyListItem>>();
ObservableRangeCollection<MyListItem> _items = new ObservableRangeCollection<MyListItem>(); ;
_items.Add(new MyListItem() { ItemName = "Test 1", ItemCount = 14 });
_items.Add(new MyListItem() { ItemName = "Test 2", ItemCount = 9 });
_items.Add(new MyListItem() { ItemName = "Test 3", ItemCount = 5 });
await _dataService.SaveAllItemsAsync(_items).ConfigureAwait(false);
_items = null;
_dataService = null;
IDataAccessService<Sample> _dataService2 = FreshIOC.Container.Resolve<IDataAccessService<AnotherSampleTable>>();
ObservableRangeCollection<Sample> _sampleList = new ObservableRangeCollection<Sample>(); ;
_sampleList.Add(new GuestGroup() { SampleName = "ABC" });
_sampleList.Add(new GuestGroup() { SampleName = "DEF" });
await _dataService2.SaveAllItemsAsync(_sampleList).ConfigureAwait(false);
_sampleList = null;
_dataService2 = null;
}
}

In your DataServiceBase constructor, you're calling DatabaseManager.CreateTableAsync() but not awaiting it, so by the time your constructor exits, that method has not yet completed running, and given that it does very little before awaiting, it's probably barely started at that point. As you can't effectively use await in a constructor, you need to remodel things so you do that initialisation at some other point; e.g. perhaps lazily when needed.
Then you also want to not use .Result/.Wait() whenever possible, especially as you're in an async method anyway (e.g. ProcessDBScripts()), so instead of doing
var _test = CurrentConnection.DropTableAsync<MyListItem>().Result;
rather do
var _test = await CurrentConnection.DropTableAsync<MyListItem>();
You also don't need to use Task.Run() for methods that return Task types anyway. So instead of
_tasks.Add(Task.Run(() => CurrentConnection.CreateTableAsync<MyListItem>().ConfigureAwait(false)));
_tasks.Add(Task.Run(() => CurrentConnection.CreateTableAsync<AnotherSampleTable>().ConfigureAwait(false)));
just do
_tasks.Add(CurrentConnection.CreateTableAsync<MyListItem>()));
_tasks.Add(CurrentConnection.CreateTableAsync<AnotherSampleTable>()));

sellotape has correctly diagnosed the code problem: the constructor is starting an asynchronous method but nothing is (a)waiting for it to complete. A simple fix would be to add await IsInitialized; to the beginning of LoadAllItemsAsync.
However, there's also a design problem:
After initialisation completed load results set and display
That's not possible on Xamarin, or any other modern UI platform. You must load your UI immediately and synchronously. What you should do is immediately display a splash/loading page and start the asynchronous initialization work. Then, when the async init is completed, update your VM/UI with your "real" page. If you just have LoadAllItemsAsync await IsInitialized, then your app will sit there for some time showing the user zero data before it "fills in".
You may find my NotifyTask<T> type (available on NuGet) useful here if you want to show a splash/spinner instead of zero data.

Management of Task.Run and stop/cancel of method and get progress

I have an application which currently runs Tasks on a time interval, however I would like more control over that, to be able to stop a running task and restart it by clicking a UI.
There are 6 tasks at the moment, but I would want to keep things generic, to be able to easily more when required. I was hoping to be able to create a wrapper to control them, which I can pass a method into as a parameter.
As such I created an object, which I create as many of as there are tasks, I can get status updates from it as well as manage it
I want to:
- Start a method/Task
- Stop a method/Task
- Restart a method/Task
- Get feedback from it's log/updates/progress/errors that I record to updates List
Is this a good way to do this, is there a better way to achieve what I'm after?
public class ManagedTask
{
public ManagedTask()
{
CreateNewToken();
}
public int Id { get; set; }
public string DescriptiveName { get; set; }
public Action<CancellationToken> TheVoidToRun { private get; set; }
private CancellationTokenSource CTokenSource { get; set; }
private CancellationToken CToken { get; set; }
private Task TheRunningThing { get; set; }
public void StartIt()
{
if (TheRunningThing == null || TheTaskStatus() == TaskStatus.Canceled || TheTaskStatus() == TaskStatus.RanToCompletion)
{
CreateNewToken();
}
// Start up the Task
AddUpdate($"Starting Task at {DateTime.Now}");
TheRunningThing = Task.Run(() => TheVoidToRun?.Invoke(CToken), CToken);
AddUpdate($"Started Task at {DateTime.Now}");
}
public void EndIt()
{
AddUpdate($"Cancelling Task at {DateTime.Now}");
CTokenSource.Cancel();
// Do - If in progress try to stop (Cancellation Token)
// Do - Stop future repeats
}
private void CreateNewToken()
{
CTokenSource = new CancellationTokenSource();
CTokenSource.Token.ThrowIfCancellationRequested();
CToken = CTokenSource.Token;
}
public TaskStatus TheTaskStatus() => TheRunningThing.Status;
internal List<string> Updates { get; set; }
private void AddUpdate(string updates)
{
// Do stuff
}
}
So I have various methods which I'd like to pass into this such like:
public class AvailableTasks
{
public async void DoStuffThatIsCancelable(CancellationToken token)
{
DoTheLongStuffOnRepeat(token);
}
public async void DoAnotherThingThatIsCancelable(CancellationToken token)
{
DoTheLongStuffOnRepeat(token);
}
private async void DoTheLongStuffOnRepeat(CancellationToken token)
{
// Do stuff
for (int i = 0; i < 20; i++)
{
while (!token.IsCancellationRequested)
{
try
{
await Task.Delay(500, token);
}
catch (TaskCanceledException ex)
{
Console.WriteLine("Task was cancelled");
continue;
}
Console.WriteLine($"Task Loop at {(i + 1) * 500}");
}
}
}
}
Here is how I was thinking of calling it.
private static readonly List<ManagedTask> _managedTasks = new List<ManagedTask>();
public static void SetupManagedTasks()
{
var at = new AvailableTasks();
var mt1 = new ManagedTask
{
Id = 1,
DescriptiveName = "The cancelable task",
TheVoidToRun = at.DoStuffThatIsCancelable,
};
_managedTasks.Add(mt1);
var mt2 = new ManagedTask
{
Id = 2,
DescriptiveName = "Another cancelable task",
TheVoidToRun = at.DoAnotherThingThatIsCancelable,
};
_managedTasks.Add(mt2);
mt1.StartIt();
mt2.StartIt();
Console.WriteLine($"{mt1.DescriptiveName} status: {mt1.TheTaskStatus()}");
Console.WriteLine($"{mt2.DescriptiveName} status: {mt2.TheTaskStatus()}");
}
public static void CancelTask(int id)
{
var mt = _managedTasks.FirstOrDefault(t => t.Id == id);
if (mt != null)
{
mt.EndIt();
Console.WriteLine($"{mt.DescriptiveName} status: {mt.TheTaskStatus()}");
}
}
public static void GetTaskStatus(int id)
{
var mt = _managedTasks.FirstOrDefault(t => t.Id == id);
if (mt != null)
{
Console.WriteLine($"{mt.DescriptiveName} status: {mt.TheTaskStatus()}");
}
}
However even with all the above, I suffer from the Status only ever showing RanToCompletion.
How can I structure the above to achieve what I want?
Thanks,
David

I suffer from the Status only ever showing RanToCompletion.
This is because your methods are using async void. They should be async Task. As I describe in my async best practices article, you should avoid async void.
Other notes...
Start a method/Task
Restart a method/Task
You can start (or restart) a task on the thread pool by using Task.Run. However, if you have naturally asynchronous tasks, then you can represent them as Func<Task> and just invoke the Func<Task> to start them.
Stop a method/Task
The only appropriate way to do this is with a CancellationToken, which it looks like you're using correctly.
Get feedback from it's log/updates/progress/errors that I record to updates List
I recommend using IProgress<T> for any kind of progress updates.

Issues Publishing From Subsequent Rebus Instances

I have several services that are essentially console applications hosted using TopShelf, and communiate using Rebus 0.99.50. One of these services (StepManager) loops through a collection of objects (of type Step), each of which contains a Bus instance, which it uses to send a message, and a handler used to handle a reply. The following Step(s) used for this example, in this order, are:
ReceiveFile
LogFileMetrics
ArchiveIncomingFile
In my actual scenario, I have a total of 7 Step(s)...When looping through these Step(s), ReceiveFile and LogFileMetrics behave as expected, however when ArchiveIncomingFile runs, .Send(req) is called, but the message never reaches its destination, leaving the process waiting for the reply that never returns. Regardless of what type of Step object or order of the objects in the list, this happens consistently at second instance of type Step (which does a .Send(req) in the Run() method) in the list. BUT, when I comment out the while (!Completed) { await Task.Delay(25); } statements, the messages appear to get sent, however without those statements, the Step(s) will all run with no specific execution order, which is a problem.
Why is this happening? What am I missing/doing wrong here? And is there a better alternative to accomplish what I am trying to do?
Here are the relevant portions of the classes in question:
public class StepManager
{
...
public string ProcessName { get; set; }
public List<Step> Steps { get; set; }
public BuiltinHandlerActivator ServiceBus { get; set; }
...
public async Task Init()
{
...
Steps = new List<Step>();
var process = Db.Processes.Include("Steps")
.Where(p => p.Name == ProcessName)
.FirstOrDefault();
...
foreach (var s in process.Steps)
{
var step = container.Resolve<Step>(s.Name);
...
Steps.Add(step);
}
}
public async Task Run()
{
foreach (var step in Steps)
{
await step.Run();
}
}
}
public class Step
{
public BuiltinHandlerActivator ServiceBus { get; set; }
public Step()
{
Db = new ClearStoneConfigContext();
Timer = new Stopwatch();
StepId = Guid.NewGuid().ToString();
Completed = false;
}
public virtual async Task Run() { }
}
public class ReceiveFile : Step
{
public ReceiveFile()
{
ServiceBus = new BuiltinHandlerActivator();
Configure.With(ServiceBus)
.Logging(l => l.ColoredConsole(LogLevel.Info))
.Routing(r => r.TypeBased().Map<ProcessLog>("stepmanager"))
.Transport(t => t.UseMsmq("receivefile"))
.Start();
}
public override async Task Run()
{
...
LogEntry.Message = "File " + FileEvent.Name + " received.";
await ServiceBus.Bus.Advanced.Routing.Send("stepmanager", LogEntry);
Completed = true;
}
}
public class LogFileMetrics : Step
{
public LogFileMetrics()
{
SubscriptionTable = "SandboxServiceBusSubscriptions";
ServiceBus = new BuiltinHandlerActivator();
Configure.With(ServiceBus)
.Logging(l => l.ColoredConsole(LogLevel.Info))
.Routing(r => r.TypeBased().Map<LogFileMetricsRequest>("metrics"))
.Transport(t => t.UseMsmq("logfilemetrics"))
.Start();
ServiceBus.Handle<FileMetricsLogged>(async msg=> await FileMetricsLogged(msg));;
}
public override async Task Run()
{
...
await ServiceBus.Bus.Send(new LogFileMetricsRequest { ProcessId = ProcessId, FileEvent = FileEvent }).ConfigureAwait(false);
while (!Completed) { await Task.Delay(25); }
}
private async Task FileMetricsLogged(FileMetricsLogged msg)
{
...
await ServiceBus.Bus.Advanced.Routing.Send("stepmanager", LogEntry);
Completed = true;
}
}
public class ArchiveIncomingFile : Step
{
public ArchiveIncomingFile()
{
SubscriptionTable = "SandboxServiceBusSubscriptions";
ServiceBus = new BuiltinHandlerActivator();
Configure.With(ServiceBus)
.Logging(l => l.ColoredConsole(LogLevel.Info))
.Routing(r => r.TypeBased().Map<ArchiveIncomingFileRequest>("incomingarchivefilerouter"))
.Transport(t => t.UseMsmq("archiveincomingfile"))
.Start();
ServiceBus.Handle<IncomingFileArchived>(async msg => await IncomingFileArchived(msg));
}
public override async Task Run()
{
...
ServiceBus.Bus.Send(req);
while (!Completed) { await Task.Delay(25); }
}
private async Task IncomingFileArchived(IncomingFileArchived msg)
{
...
await ServiceBus.Bus.Advanced.Routing.Send("stepmanager", LogEntry);
Completed = true;
}
}

I can see several issues with your code, although it is not clear to me what is causing the funny behavior you are experiencing.
First off, it seems like you are creating new bus instances every time you are creating steps. Are you aware that Rebus' bus instance is supposed to be created once at startup in your application, kept as a singleton, and must be properly disposed when your application shuts down?
You can of course perform this create-dispose cycle as many times as you like, it's not like Rebus will leave anything behind in any way, but the fact that you are NOT disposing the bus anywhere tells me that your application probably forgets to do this.
You can read more on the Rebus wiki, especially in the section about Rebus' bus instance.
Another issue is the subtle potential race condition in the ArchiveIncomingFile class whose ctor looks like this:
public ArchiveIncomingFile()
{
SubscriptionTable = "SandboxServiceBusSubscriptions";
ServiceBus = new BuiltinHandlerActivator();
Configure.With(ServiceBus)
.Logging(l => l.ColoredConsole(LogLevel.Info))
.Routing(r => r.TypeBased().Map<ArchiveIncomingFileRequest>("incomingarchivefilerouter"))
.Transport(t => t.UseMsmq("archiveincomingfile"))
.Start();
//<<< bus is receiving messages at this point, but there's no handler!!
ServiceBus.Handle<IncomingFileArchived>(async msg => await IncomingFileArchived(msg));
}
As you can see, there is a (very very very short, admittedly) time (marked by //<<<) in which the bus has been started (and thus will start to pull messages out of its input queue) where no handlers yet have been configured.
You should be sure to configure handlers BEFORE you start the bus.
Finally, you are asking
And is there a better alternative to accomplish what I am trying to do?
but I am unable to answer that question because I simply cannot figure out what you are trying to do ;)
(but if you explain to me at a slightly higher level what problem you are trying to solve, I might have some hints for you :))