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Explain semantics of multiple calls to CancellationTokenSource.Cancel #11105

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Explain semantics of multiple calls to CancellationTokenSource.Cancel #11105

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5a2b566
Explain semantics of multiple calls to `CancellationTokenSource.Cancel`
Smaug123 Mar 18, 2025
45f918e
'will be notified' -> 'is notified'
Smaug123 Mar 25, 2025
8094c7a
Consistently use the present tense
Smaug123 Mar 25, 2025
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22 changes: 13 additions & 9 deletions xml/System.Threading/CancellationTokenSource.xml
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Expand Up @@ -381,13 +381,15 @@
<format type="text/markdown"><![CDATA[

## Remarks
The associated <xref:System.Threading.CancellationToken> will be notified of the cancellation and will transition to a state where <xref:System.Threading.CancellationToken.IsCancellationRequested%2A> returns true.

Any callbacks or cancelable operations registered with the <xref:System.Threading.CancellationToken> will be executed.
The associated <xref:System.Threading.CancellationToken> is notified of the cancellation and transitions to a state where <xref:System.Threading.CancellationToken.IsCancellationRequested%2A> returns true.

Any callbacks or cancelable operations registered with the <xref:System.Threading.CancellationToken> are executed, if they haven't already been executed by a previous call to <xref:System.Threading.CancellationTokenSource.Cancel>. Subsequent calls to <xref:System.Threading.CancellationTokenSource.Cancel> won't execute the same callback again unless reregistered. (Avoid multiple calls to <xref:System.Threading.CancellationTokenSource.Cancel>, because the intent of such code is often unclear.)

Callbacks are executed synchronously in LIFO order.

We recommend that cancelable operations and callbacks registered with <xref:System.Threading.CancellationToken> not throw exceptions.

This overload of Cancel will aggregate any exceptions thrown into an <xref:System.AggregateException>, such that one callback throwing an exception will not prevent other registered callbacks from being executed.
This overload of Cancel aggregates any exceptions thrown into an <xref:System.AggregateException>, such that one callback throwing an exception will not prevent other registered callbacks from being executed.

Calling this method has the same effect as calling [`Cancel(false)`](xref:System.Threading.CancellationTokenSource.Cancel(System.Boolean)).

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<format type="text/markdown"><![CDATA[

## Remarks
The associated <xref:System.Threading.CancellationToken> will be notified of the cancellation and will transition to a state where <xref:System.Threading.CancellationToken.IsCancellationRequested%2A> returns `true`.
The associated <xref:System.Threading.CancellationToken> is notified of the cancellation and transitions to a state where <xref:System.Threading.CancellationToken.IsCancellationRequested%2A> returns `true`.

Any callbacks or cancelable operations registered with the <xref:System.Threading.CancellationToken> will be executed. Callbacks will be executed synchronously in LIFO order.
Any callbacks or cancelable operations registered with the <xref:System.Threading.CancellationToken> are executed, if they haven't already been executed by a previous call to <xref:System.Threading.CancellationTokenSource.Cancel>. Subsequent calls to <xref:System.Threading.CancellationTokenSource.Cancel> won't execute the same callback again unless reregistered. (Avoid multiple calls to <xref:System.Threading.CancellationTokenSource.Cancel>, because the intent of such code is often unclear.)

Callbacks are executed synchronously in LIFO order.

We recommend that cancelable operations and callbacks registered with <xref:System.Threading.CancellationToken> not throw exceptions.

If `throwOnFirstException` is `true`, an exception will immediately propagate out of the call to <xref:System.Threading.CancellationTokenSource.Cancel%2A>, preventing the remaining callbacks and cancelable operations from being processed.

If `throwOnFirstException` is `false`, this overload will aggregate any exceptions thrown into an <xref:System.AggregateException>, such that one callback throwing an exception will not prevent other registered callbacks from being executed.
If `throwOnFirstException` is `false`, this overload aggregates any exceptions thrown into an <xref:System.AggregateException>, such that one callback throwing an exception will not prevent other registered callbacks from being executed.

]]></format>
</remarks>
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<summary>Communicates a request for cancellation asynchronously.</summary>
<returns>A task that will complete after cancelable operations and callbacks registered with the associated <see cref="T:System.Threading.CancellationToken" /> have completed.</returns>
<remarks>
<para> The associated <see cref="T:System.Threading.CancellationToken" /> will be notified of the cancellation and will synchronously transition to a state where <see cref="P:System.Threading.CancellationToken.IsCancellationRequested" /> returns <see langword="true" />.
Any callbacks or cancelable operations registered with the <see cref="T:System.Threading.CancellationToken" /> will be executed asynchronously, with the returned <see cref="T:System.Threading.Tasks.Task" /> representing their eventual completion.
<para> The associated <see cref="T:System.Threading.CancellationToken" /> is notified of the cancellation and synchronously transitions to a state where <see cref="P:System.Threading.CancellationToken.IsCancellationRequested" /> returns <see langword="true" />.
Any callbacks or cancelable operations registered with the <see cref="T:System.Threading.CancellationToken" /> will be executed asynchronously, with the returned <see cref="T:System.Threading.Tasks.Task" /> representing their eventual completion.
</para>
<para> Callbacks registered with the token should not throw exceptions.
However, any such exceptions that are thrown will be aggregated into an <see cref="T:System.AggregateException" />, such that one callback throwing an exception will not prevent other registered callbacks from being executed.
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