在Go中为SQL连接设置TCP超时

Question

When I connect to database (using standard go sql library) using VPN and VPN interface goes down, there's a 75 seconds timeout when I try to do SQL query, no matter if the interface goes up meanwhile. I'd like to decrease this timeout to some reasonable time, so my application won't be frozen for 75 seconds in such case.

db, err := sql.Open(driverName, dataSourceName)

Is it possible to set it somehow via db variable?

Answer 1

Starting with Go 1.8, the sql.DB abstraction now accepts context.Context, which can be used to time out connections faster.

func (c *Client) DoLookup(ctx context.Context, id int) (string, error) {
  var name string
  // create a child context with a timeout
  newCtx, cancel := context.WithTimeout(ctx, time.Second)
  // release resources used in `newCtx` if
  // the DB operation finishes faster than the timeout
  defer cancel()

  row := c.db.QueryRowContext(newCtx, "SELECT name FROM items WHERE id = ?", id)

  err := row.Scan(&name)
  if err != nil {
    return "", err
  }

  return name, nil
}

If your DoLookup function doesn't yet take a context.Context (and it really should!) you can create a parent one by calling context.TODO().