[Question] Necessary to check IsReplaying before SetCustomStatus?

[colbylwilliams]

Question

Is it necessary to check if an orchestration function is replaying before setting a custom status? For example:

if (!functionContext.IsReplaying)
    functionContext.SetCustomStatus("Creating Project");

var _ = await functionContext
      .CallActivityAsync<Guid>(nameof(CreateProjectActivity), project);

if (!functionContext.IsReplaying)
    functionContext.SetCustomStatus("Creating Project Users");

var _ = await functionContext
      .CallActivityAsync<Guid>(nameof(CreateProjectUsersActivity), project);

functionContext.SetCustomStatus("Project Created");

Or is this handled automatically? I'd assume replays are fast, but I'm not sure how long it takes for the CustomStatus to be persisted and available via the HTTP APIs. So if I don't check IsReplaying is there an (edge) chance that the HTTP API could return "Creating Project" even though CreateProjectUsersActivity is really already finished? (i.e. the HTTP API was queried mid-replay)

[cgillum]

It's not necessary to check for IsReplaying.

The SetCustomStatus API doesn't actually do any I/O at the time you call it. Rather, it just updates some in-memory state. The I/O happens at the point where we checkpoint the updated instance history (usually the next await statement). Only the data saved in the last SetCustomStatus call will get persisted. This also means that you'll never see a "Creating Project" status when querying the instance status, even if the query happens mid-replay.

Does that help clarify?

[colbylwilliams]

Yep makes sense. Thanks @cgillum