#pulsar/internal/connection.go 
type connection struct {
    logicalAddr  *url.URL
    physicalAddr *url.URL
}
......
func (c *connection) waitUntilReady() error {
    select {
    case <-c.readyCh:
       return nil
    case <-c.closeCh:
       // Connection has been closed while waiting for the readiness.
       return errors.New("connection error")
    }
}