Function createOrFindOrder

samples/order/processor.go:130–160

createOrFindOrder either creates a new order from req (the usual case), or returns an existing unfinished order. It returns a nil *Order if the order exists and is finished, that is, this request message is a duplicate. createOrFindOrder returns a non-nil error only for database problems.

(ctx context.Context, coll *docstore.Collection, req *OrderRequest)

// finished, that is, this request message is a duplicate.
// createOrFindOrder returns a non-nil error only for database problems.
func createOrFindOrder(ctx context.Context, coll *docstore.Collection, req *OrderRequest) (*Order, error) {
	// See if there is already a document for this order.
	order := &Order{ID: req.ID}
	err := coll.Get(ctx, order)
	if err != nil {
		if gcerrors.Code(err) != gcerrors.NotFound {
			return nil, err
		}
		// Normal case: the order wasn't found, because it hasn't been created
		// yet. Create it.
		order = &Order{
			ID:         req.ID,
			Email:      req.Email,
			InImage:    req.InImage,
			CreateTime: req.CreateTime,
		}
		if err := coll.Create(ctx, order); err != nil {
			return nil, err
		}
		return order, nil
	}
	if order.FinishTime.IsZero() {
		// The order exists, but was not finished. Either it was abandoned by the processor that
		// was working on it (probably because the processor died), or it is in progress. Assume
		// that it was abandoned, and process it.
		return order, nil
	}
	// The order exists and was finished. This is most likely the result of a pubsub redelivery.
	// We simply ignore it.
	return nil, nil
}

// processOrder processes the order request.
func (p *processor) processOrder(ctx context.Context, order *Order) error {