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moby--moby/pkg/progress/progressreader.go

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package progress
import (
"io"
)
// Reader is a Reader with progress bar.
type Reader struct {
in io.ReadCloser // Stream to read from
out Output // Where to send progress bar to
size int64
current int64
lastUpdate int64
id string
action string
}
// NewProgressReader creates a new ProgressReader.
func NewProgressReader(in io.ReadCloser, out Output, size int64, id, action string) *Reader {
return &Reader{
in: in,
out: out,
size: size,
id: id,
action: action,
}
}
func (p *Reader) Read(buf []byte) (n int, err error) {
read, err := p.in.Read(buf)
p.current += int64(read)
updateEvery := int64(1024 * 512) //512kB
if p.size > 0 {
// Update progress for every 1% read if 1% < 512kB
if increment := int64(0.01 * float64(p.size)); increment < updateEvery {
updateEvery = increment
}
}
if p.current-p.lastUpdate > updateEvery || err != nil {
p.updateProgress(err != nil && read == 0)
p.lastUpdate = p.current
}
return read, err
}
// Close closes the progress reader and its underlying reader.
func (p *Reader) Close() error {
if p.current < p.size {
// print a full progress bar when closing prematurely
p.current = p.size
p.updateProgress(false)
}
return p.in.Close()
}
func (p *Reader) updateProgress(last bool) {
p.out.WriteProgress(Progress{ID: p.id, Action: p.action, Current: p.current, Total: p.size, LastUpdate: last})
}