Adding executionStartedTimestamp property to ExecutionStartedEvent message

[ASHIQUEMD]

This PR adds executionStartedTimestamp property to ExecutionStartedEvent, to capture the execution started timestamp for workflow.

We are adding this property to capture workflowExecutionElapsed time, and this needs workflowExecutionStartedTime to be captured and saved.

[cgillum]

We should not be adding this property here. An indication of when execution started should instead be done on OrchestrationState.

[ASHIQUEMD]

We should not be adding this property here. An indication of when execution started should instead be done on OrchestrationState.

Hello @cgillum, thank you for your suggestion. I wanted to clarify that we don't directly persist OrchestrationState; it is derived from HistoryEvent. If I understand correctly, you're proposing adding executionStartedTimestamp to OrchestrationState. If that's the case, the challenge lies in persisting this information, as I couldn't find an exposed API in dtf-go to save the OrchestrationState directly. The available API, FetchOrchestrationMetadata, retrieves the state from HistoryEvent. Please correct me if my understanding is not accurate or if there's a different approach you have in mind.

Just FYI: We are adding this property to capture workflowExecutionLatency time (PR), and this needs workflowExecutionStartedTime to be captured and saved. So, WorkflowExecutionStartedEvent struct seemed like a good fit to store executionStartedTimestamp property.

[DeepanshuA]

Yeah, OrchestrationState is not persisted directly. It is created through workflowState saved by backend. And, this workflowState is being saved in terms of HistoryEvents.
So, I also understand the same thing that we would need to persist in ExecutionStartedEvent and that should be the correct place for it.

[cgillum]

You don't need a new property for this. You can use the timestamp on the very first HistoryEvent of type OrchestratorStarted in the history, which gets added only after the orchestration starts executing.

[ASHIQUEMD]

Closing this PR as it is no longer required.