longrunning

func (*Operation) Cancel ¶

func (op *Operation) Cancel(ctx context.Context, opts ...gax.CallOption) error

Cancel starts asynchronous cancellation on a long-running operation. The server makes a best effort to cancel the operation, but success is not guaranteed. If the server doesn't support this method, it returns status.Code(err) == codes.Unimplemented. Clients can use Poll or other methods to check whether the cancellation succeeded or whether the operation completed despite cancellation. On successful cancellation, the operation is not deleted; instead, op.Poll returns an error with code Canceled.

op, err := bestMomentInHistory()
if err != nil {
	// TODO: Handle err.
}
if err := op.Cancel(context.Background()); err != nil {
	// TODO: Handle err.
}

func (*Operation) Delete ¶

func (op *Operation) Delete(ctx context.Context, opts ...gax.CallOption) error

Delete deletes a long-running operation. This method indicates that the client is no longer interested in the operation result. It does not cancel the operation. If the server doesn't support this method, status.Code(err) == codes.Unimplemented.

op, err := bestMomentInHistory()
if err != nil {
	// TODO: Handle err.
}
if err := op.Delete(context.Background()); err != nil {
	// TODO: Handle err.
}

func (*Operation) Done ¶

func (op *Operation) Done() bool

Done reports whether the long-running operation has completed.

func (*Operation) Metadata ¶

func (op *Operation) Metadata(meta protoadapt.MessageV1) error

Metadata unmarshals op's metadata into meta. If op does not contain any metadata, Metadata returns ErrNoMetadata and meta is unmodified.

op, err := bestMomentInHistory()
if err != nil {
	// TODO: Handle err.
}

// The operation might contain metadata.
// In this example, the metadata contains the estimated length of time
// the operation might take to complete.
var meta durationpb.Duration
if err := op.Metadata(&meta); err != nil {
	// TODO: Handle err.
}
if err := meta.CheckValid(); err == ErrNoMetadata {
	fmt.Println("no metadata")
	return
} else if err != nil {
	// TODO: Handle err.
	return
}
fmt.Println(meta.AsDuration())

Output:

1h0m0s

func (*Operation) Name ¶

func (op *Operation) Name() string

Name returns the name of the long-running operation. The name is assigned by the server and is unique within the service from which the operation is created.

func (*Operation) Poll ¶

func (op *Operation) Poll(ctx context.Context, resp protoadapt.MessageV1, opts ...gax.CallOption) error

Poll fetches the latest state of a long-running operation.

If Poll fails, the error is returned and op is unmodified. If Poll succeeds and the operation has completed with failure, the error is returned and op.Done will return true. If Poll succeeds and the operation has completed successfully, op.Done will return true; if resp != nil, the response of the operation is stored in resp.

func (*Operation) Wait ¶

func (op *Operation) Wait(ctx context.Context, resp protoadapt.MessageV1, opts ...gax.CallOption) error

Wait is equivalent to WaitWithInterval using DefaultWaitInterval.

// Complex computation, might take a long time.
op, err := bestMomentInHistory()
if err != nil {
	// TODO: Handle err.
}
var ts timestamppb.Timestamp
err = op.Wait(context.TODO(), &ts)
if err != nil && !op.Done() {
	fmt.Println("failed to fetch operation status", err)
} else if err != nil && op.Done() {
	fmt.Println("operation completed with error", err)
} else {
	fmt.Println(ts.AsTime().Format(time.RFC3339Nano))
}

Output:

2009-11-10T23:00:00Z

func (*Operation) WaitWithInterval ¶

func (op *Operation) WaitWithInterval(ctx context.Context, resp protoadapt.MessageV1, interval time.Duration, opts ...gax.CallOption) error

WaitWithInterval blocks until the operation is completed. If resp != nil, Wait stores the response in resp. WaitWithInterval polls every interval, except initially when it polls using exponential backoff.

See documentation of Poll for error-handling information.