New Update-With-Start API

[dandavison]

New Update-With-Start API.

• Instead of using ExecuteWorkflow, update-with-start is invoked via a new method UpdateWithStartWorkflow on Client which returns an UpdateHandle
• The method receives a WithStartWorkflowOperation struct which defines the start operation, and exposes a method to obtain the workflow run:

The snippet below is from the accompanying sample: temporalio/samples-go#370:

tx := earlyreturn.Transaction{ID: uuid.New(), SourceAccount: "Bob", TargetAccount: "Alice", Amount: 100}

startWorkflowOp := c.NewWithStartWorkflowOperation(client.StartWorkflowOptions{
	ID:                       "early-return-workflow-ID-" + tx.ID,
	WorkflowIDConflictPolicy: enumspb.WORKFLOW_ID_CONFLICT_POLICY_FAIL,
	TaskQueue:                earlyreturn.TaskQueueName,
}, earlyreturn.Workflow, tx)

updateHandle, err := c.UpdateWithStartWorkflow(ctxWithTimeout, client.UpdateWithStartWorkflowOptions{
	UpdateOptions: client.UpdateWorkflowOptions{
		UpdateName:   earlyreturn.UpdateName,
		WaitForStage: client.WorkflowUpdateStageCompleted,
	},
	StartOperation: startWorkflowOp,
})
if err != nil {
	log.Fatalln("Error issuing update-with-start:", err)
}
var earlyReturnResult any
err = updateHandle.Get(ctxWithTimeout, &earlyReturnResult)
if err != nil {
	// The workflow will continue running, cancelling the transaction.

	// NOTE: If the error is retryable, a retry attempt must use a unique workflow ID.
	log.Fatalln("Error obtaining update result:", err)
}

workflowRun, err := startWorkflowOp.Get(ctxWithTimeout)