Class JoinableTaskContextNode

Namespace

Microsoft.VisualStudio.Threading

Assembly

Microsoft.VisualStudio.Threading.dll

A customizable source of JoinableTaskFactory instances.

public class JoinableTaskContextNode

Inheritance

object

JoinableTaskContextNode

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Constructors

JoinableTaskContextNode(JoinableTaskContext)

Initializes a new instance of the JoinableTaskContextNode class.

public JoinableTaskContextNode(JoinableTaskContext context)

Parameters

context JoinableTaskContext

The inner JoinableTaskContext.

Properties

Context

Gets the inner wrapped context.

public JoinableTaskContext Context { get; }

Property Value

JoinableTaskContext

Factory

Gets the factory which creates joinable tasks that do not belong to a joinable task collection.

public JoinableTaskFactory Factory { get; }

Property Value

JoinableTaskFactory

IsOnMainThread

Gets a value indicating whether the caller is executing on the main thread.

public bool IsOnMainThread { get; }

Property Value

bool

MainThread

Gets the main thread that can be shared by tasks created by this context.

public Thread MainThread { get; }

Property Value

Thread

Methods

CreateCollection()

Creates a collection for in-flight joinable tasks.

public JoinableTaskCollection CreateCollection()

Returns

JoinableTaskCollection

A new joinable task collection.

CreateDefaultFactory()

Creates a factory without a JoinableTaskCollection.

protected virtual JoinableTaskFactory CreateDefaultFactory()

Returns

JoinableTaskFactory

Remarks

Used for initializing the Factory property.

CreateFactory(JoinableTaskCollection)

Creates a joinable task factory that automatically adds all created tasks to a collection that can be jointly joined.

public virtual JoinableTaskFactory CreateFactory(JoinableTaskCollection collection)

Parameters

collection JoinableTaskCollection

The collection that all tasks should be added to.

Returns

JoinableTaskFactory

IsMainThreadBlocked()

Gets a value indicating whether the main thread is blocked for the caller's completion.

public bool IsMainThreadBlocked()

Returns

bool

OnFalseHangDetected(TimeSpan, Guid)

Invoked when an earlier hang report is false alarm.

protected virtual void OnFalseHangDetected(TimeSpan hangDuration, Guid hangId)

Parameters

hangDuration TimeSpan

The duration of the total waiting time.

hangId Guid

A GUID that uniquely identifies the earlier hang report.

OnHangDetected(HangDetails)

Invoked when a hang is suspected to have occurred involving the main thread.

protected virtual void OnHangDetected(JoinableTaskContext.HangDetails details)

Parameters

details JoinableTaskContext.HangDetails

Describes the hang in detail.

Remarks

A single hang occurrence may invoke this method multiple times, with increasing values in the NotificationCount values in the details parameter.

OnHangDetected(TimeSpan, int, Guid)

Invoked when a hang is suspected to have occurred involving the main thread.

protected virtual void OnHangDetected(TimeSpan hangDuration, int notificationCount, Guid hangId)

Parameters

hangDuration TimeSpan

The duration of the current hang.

notificationCount int

The number of times this hang has been reported, including this one.

hangId Guid

A random GUID that uniquely identifies this particular hang.

Remarks

A single hang occurrence may invoke this method multiple times, with increasing values in the hangDuration parameter.

RegisterOnHangDetected()

Registers with the inner JoinableTaskContext to receive hang notifications.

protected IDisposable RegisterOnHangDetected()

Returns

IDisposable

A value to dispose of to cancel hang notifications.

SuppressRelevance()

Conceals any JoinableTask the caller is associated with until the returned value is disposed.

public JoinableTaskContext.RevertRelevance SuppressRelevance()

Returns

JoinableTaskContext.RevertRelevance

A value to dispose of to restore visibility into the caller's associated JoinableTask, if any.

Remarks

In some cases asynchronous work may be spun off inside a delegate supplied to Run, so that the work does not have privileges to re-enter the Main thread until the Run(Func<Task>) call has returned and the UI thread is idle. To prevent the asynchronous work from automatically being allowed to re-enter the Main thread, wrap the code that calls the asynchronous task in a using block with a call to this method as the expression.

this.JoinableTaskContext.RunSynchronously(async delegate {
    using(this.JoinableTaskContext.SuppressRelevance()) {
        var asyncOperation = Task.Run(async delegate {
            // Some background work.
            await this.JoinableTaskContext.SwitchToMainThreadAsync();
            // Some Main thread work, that cannot begin until the outer RunSynchronously call has returned.
        });
    }

    // Because the asyncOperation is not related to this Main thread work (it was suppressed),
    // the following await *would* deadlock if it were uncommented.
    ////await asyncOperation;
});