Task <T> CompensateAsync(Task <T> task, Func <Task <T>, Task <T> > compensationTask)
{
var source = new TaskCompletionSource <Task <T> >();
task.ContinueWith((Task <T> innerTask) =>
{
if (innerTask.IsCanceled)
{
return(source.TrySetCanceled());
}
return(source.TrySetResult(TaskUtil.Completed(innerTask.Result)));
},
TaskContinuationOptions.NotOnFaulted | TaskContinuationOptions.ExecuteSynchronously);
task.ContinueWith((Task <T> innerTask) =>
{
try
{
Task <T> resultTask = compensationTask(innerTask);
if (resultTask == null)
{
throw new InvalidOperationException("Sure could use a Task here buddy");
}
source.TrySetResult(resultTask);
}
catch (Exception ex)
{
source.TrySetException(ex);
}
}, TaskContinuationOptions.OnlyOnFaulted | TaskContinuationOptions.ExecuteSynchronously);
return(source.Task.FastUnwrap());
}
public TaskComposer(T payload, CancellationToken cancellationToken = default(CancellationToken))
{
_payload = payload;
_cancellationToken = cancellationToken;
_task = cancellationToken.IsCancellationRequested
? TaskUtil.Canceled <T>()
: TaskUtil.Completed(payload);
}
CompensationResult <T> Compensation <T> .Handled(T payload)
{
return(new Result(TaskUtil.Completed(payload)));
}
