Go: `defer` executing a last activity?

Community Support
1

In the documentation of the Go SDK, I see the defer used to complete a session. But when not using sessions, can I also use defer to execute a last workflow activity.

Conceptually, I want to execute a cleanup activity no matter the outcome of the previous activities.

e.g.

defer workflow.ExecuteActivity(ctx, activities.Cleanup, tenant, application)
2

Yes, executing any workflow code including activities is supported in the defer.

You should be careful about context passed to ExecuteActivity as it can be already cancelled. So I recommend using a disconnected context created through workflow.NewDisconnectedContext in the cleanup code.

3

@maxim I moved the following line close to the top of my workflow implementation and added the new context:

cleanupCtx, _ := workflow.NewDisconnectedContext(ctx)
defer workflow.ExecuteActivity(cleanupCtx, activities.Cleanup, tenant, application).Get(cleanupCtx, &result)

Should the Get(cleanupCtx, &result) be appended? With this function chaining, I’m not sure what I am deferring.

4

defer is tricky and I wouldn’t rely on it to execute the code you posted correctly. I would change it to:

defer func() { 
   workflow.ExecuteActivity(cleanupCtx, activities.Cleanup, tenant, application).Get(cleanupCtx, &result)
}()

to be on the safe side.