JoinableTaskContext.SuppressRelevance Method
Definition
Important
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Conceals any JoinableTask the caller is associated with until the returned value is disposed.
public:
Microsoft::VisualStudio::Threading::JoinableTaskContext::RevertRelevance SuppressRelevance();public Microsoft.VisualStudio.Threading.JoinableTaskContext.RevertRelevance SuppressRelevance ();member this.SuppressRelevance : unit -> Microsoft.VisualStudio.Threading.JoinableTaskContext.RevertRelevancePublic Function SuppressRelevance () As JoinableTaskContext.RevertRelevanceReturns
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;
});