Generate DkmEvaluationResults asynchronously

[cston]

Generate subsequent DkmEvaluationResults asynchronously rather than in completion from previous DkmEvaluationResults to avoid stack overflow when many items are requested and evaluation is not already asynchronous (when EvaluateDebuggerDisplayString is not used).

[cston]

@KevinH-MS, @amcasey, @pnelsonmsft

[amcasey]

As far as I can tell, there are three kinds of completion routines floating around, WorkListCompletionRoutine, CompletionRoutine, and DkmCompletionRoutine. However, we seem to call locals of all three types "completionRoutine". I think the code would be much easier to follow if we gave them distinct names.

[cston]

I've removed WorkListCompletionRoutine.

[amcasey]

Consider splitting CompletionRoutine into

internal delegate void ExceptionCompletionRoutine(Exception exception);
internal delegate void SuccessCompletionRoutine(DkmEvaluationResult result);

[amcasey]

It looks like we could call wl.ContinueWith outside the lambda (e.g. immediately after construction).

[cston]

The lambda passed to wl.ContinueWith must be the last continuation, after any added while executing GetEvaluationResultsAndContinue.

[KevinH-MS]

If this isn't part of the real type, can we add a doc comment?

[VladimirReshetnikov]

Consider using => body for trivial properties.

[KevinH-MS]

LGTM

[KevinH-MS]

Should this be "index < numRows"?

[cston]

numRows - 1 since we're deciding whether to evaluate row index + 1.

[KevinH-MS]

Would we get the same result if we changed it to "index < numRows" and removed the "else..."? That is, would the outer if catch it and call the completion routine when we call GetEvaluationResultsAndContinue with "index + 1"?

[KevinH-MS]

Actually, could we remove the if/else from the lambda entirely and just call GetEvaluationResultsAndContinue (relying on the outer if to call the completionRoutine)?