Files
kind/pkg/internal/util/cli/spinner.go
2019-09-06 23:58:09 -07:00

120 lines
2.4 KiB
Go

/*
Copyright 2018 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package cli
import (
"fmt"
"io"
"sync"
"time"
)
// custom CLI loading spinner for kind
var spinnerFrames = []string{
"⠈⠁",
"⠈⠑",
"⠈⠱",
"⠈⡱",
"⢀⡱",
"⢄⡱",
"⢄⡱",
"⢆⡱",
"⢎⡱",
"⢎⡰",
"⢎⡠",
"⢎⡀",
"⢎⠁",
"⠎⠁",
"⠊⠁",
}
// Spinner is a simple and efficient CLI loading spinner used by kind
// It is simplistic and assumes that the line length will not change.
type Spinner struct {
stop chan struct{}
ticker *time.Ticker
writer io.Writer
mu *sync.Mutex
// protected by mu
prefix string
suffix string
}
// spinner implements writer
var _ io.Writer = &Spinner{}
// NewSpinner initializes and returns a new Spinner that will write to w
func NewSpinner(w io.Writer) *Spinner {
return &Spinner{
stop: make(chan struct{}, 1),
ticker: time.NewTicker(time.Millisecond * 100),
mu: &sync.Mutex{},
writer: w,
}
}
// SetPrefix sets the prefix to print before the spinner
func (s *Spinner) SetPrefix(prefix string) {
s.mu.Lock()
s.prefix = prefix
s.mu.Unlock()
}
// SetSuffix sets the suffix to print after the spinner
func (s *Spinner) SetSuffix(suffix string) {
s.mu.Lock()
s.suffix = suffix
s.mu.Unlock()
}
// Start starts the spinner running
func (s *Spinner) Start() {
go func() {
for {
for _, frame := range spinnerFrames {
select {
case <-s.stop:
return
case <-s.ticker.C:
func() {
s.mu.Lock()
defer s.mu.Unlock()
fmt.Fprintf(s.writer, "\r%s%s%s", s.prefix, frame, s.suffix)
}()
}
}
}
}()
}
// Stop signals the spinner to stop
func (s *Spinner) Stop() {
s.stop <- struct{}{}
}
// Write implements io.Writer, interrupting the spinner and writing to
// the inner writer
func (s *Spinner) Write(p []byte) (n int, err error) {
s.Stop()
if _, err := s.writer.Write([]byte("\r")); err != nil {
return 0, err
}
n, err = s.writer.Write(p)
s.Start()
return n, err
}