Proposal: Make AsyncTaskCodeActivity derive from AsyncCodeActivity instead of TaskCodeActivity<object> #186
Description
The AsyncTaskCodeActivity should not have a Result property. This causes problems in some scenarios with reflection and validation.
There are two ways to solve thje problem:
Create a TaskCodeActivity as a companion for TaskCodeActivity`1 or let the AsyncTaskCodeActivity derive directly from AsyncCodeActivity.
Here's an example implementation, which uses AsyncCodeActivity directly, as the TaskCodeActivity`1 implementation looks unnecessary even though there is a little bit of code duplication:
/// <summary>
/// Activity that executes a <see cref="Task"/> which allows the usage of async/await.
/// </summary>
public abstract class AsyncTaskCodeActivity : AsyncCodeActivity
{
/// <inheritdoc />
protected sealed override IAsyncResult BeginExecute(
AsyncCodeActivityContext context,
AsyncCallback callback,
object state)
{
var cancellationTokenSource = new CancellationTokenSource();
context.UserState = cancellationTokenSource;
return ApmAsyncFactory.ToBegin(
ExecuteAsync(context, cancellationTokenSource.Token),
callback,
state);
}
/// <inheritdoc />
protected sealed override void EndExecute(
AsyncCodeActivityContext context,
IAsyncResult result)
{
((CancellationTokenSource)context.UserState).Dispose();
}
/// <inheritdoc />
protected sealed override void Cancel(AsyncCodeActivityContext context) =>
((CancellationTokenSource)context.UserState).Cancel();
/// <summary>
/// Called to execute this activity.
/// </summary>
/// <param name="context">The context.</param>
/// <param name="cancellationToken">The <see cref="CancellationToken"/>.</param>
/// <returns>The task.</returns>
/// <remarks>
/// The <see cref="AsyncCodeActivityContext.UserState"/> must not be used/altered.
/// </remarks>
protected abstract Task ExecuteAsync(
AsyncCodeActivityContext context,
CancellationToken cancellationToken);
}