Add API to allow forcing creation of a Activity using ActivitySource (rather than relying on ActivityListener)

[shirhatti]

Background and Motivation

Forcing creation of an Activity will allow existing codebases (e.g., aspnetcore) to migrate to using ActivitySource to create Activitys while still preserving compat with existing DiagnosticListeners.

Proposed API

namespace System.Diagnostics.DiagnosticSource
{
  public sealed class ActivitySource
  {
+   public System.Diagnostics.Activity? StartActivity (string name,
+                                                      System.Diagnostics.ActivityKind kind,
+                                                      string parentId,
+                                                      bool forceCreation,
+                                                      System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string,object?>>? tags = default,
+                                                      System.Collections.Generic.IEnumerable<System.Diagnostics.ActivityLink>? links = default,
+                                                      DateTimeOffset startTime = default);
  }
}

Usage Examples

dotnet/aspnetcore#30089

Alternative Designs

The alternative design to achieve compat with DiagnosticListener was to create a dummy ActivityListener. However, the decision to sample/or not sample can change frequently (on a per request-basis), making it expensive to mutate the Sample/SampleUsingParentId delegate in a thread-safe.

Risks

When used incorrectly, forcing creation of an Activity could be a potentially expensive/high-allocation operation.

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Issue Details

---

Background and Motivation

Forcing creation of an Activity will allow existing codebases (e.g., aspnetcore) to migrate to using ActivitySource to create Activitys while still preserving compat with existing DiagnosticListeners.

Proposed API

namespace System.Diagnostics.DiagnosticSource
{
  public sealed class ActivitySource
  {
+   public System.Diagnostics.Activity? StartActivity (string name,
+                                                      System.Diagnostics.ActivityKind kind,
+                                                      string parentId,
+                                                      bool forceCreation,
+                                                      System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string,object?>>? tags = default,
+                                                      System.Collections.Generic.IEnumerable<System.Diagnostics.ActivityLink>? links = default,
+                                                      DateTimeOffset startTime = default);
  }
}

Usage Examples

dotnet/aspnetcore#30089

Alternative Designs

The alternative design to achieve compat with DiagnosticListener was to create a dummy ActivityListener. However, the decision to sample/or not sample can change frequently (on a per request-basis), making it expensive to mutate the Sample/SampleUsingParentId delegate in a thread-safe.

Risks

When used incorrectly, forcing creation of an Activity could be a potentially expensive/high-allocation operation.

Author:	shirhatti
Assignees:	-
Labels:	api-suggestion, area-System.Diagnostics.Activity
Milestone:	-

[tarekgh]

Properly we should combine the request here with the one in #43853 in a single proposal.

[tarekgh]

@shirhatti if you are satisfied with the workaround proposed by @noahfalk, can we close this request? just for the record here is some high level idea how to force the Activity creation:

	Activity activity = null;
    if (activitySource.HasListeners())
    {
        activity = activitySource.StartActivity(...);
    }
    if (activity == null)
    {
        activity = new Activity(...);
        ...
        activity.Start();
    }

Please let me know if have any question.

[mjeanrichard]

Just for reference, this is basically the solution for my question over here #45843

[shirhatti]

As mentioned in the other thread, Activities created using new Activity() don't have ActivityKind and ActivitySource correctly populated.

As a consequence, a diagnostic listener subscriber will see different behavior based on whether there is another ActivityListener in the process. I'm not a fan of having unrelated subscribers cause side-effects.

That being said, I could be convinced if both you and @noahfalk agree that these minor behavior differences are acceptable

[shirhatti]

Closing since I have been convinced otherwise 😄