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progress_reader.go
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/
progress_reader.go
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package main
import (
"io"
"math"
"os"
)
type ProgressReader struct {
io.Reader
currentOffset int64
totalBytes int64
progressFunc func(currentProgress float64)
}
func NewProgressReader(r io.Reader, progressFunc func(float64)) (*ProgressReader, error) {
pr := &ProgressReader{
Reader: r,
currentOffset: 0,
totalBytes: 0,
progressFunc: progressFunc,
}
if r, ok := r.(*os.File); ok {
stat, err := r.Stat()
if err != nil {
return nil, err
}
pr.totalBytes = stat.Size()
}
return pr, nil
}
func (p *ProgressReader) Read(buf []byte) (int, error) {
n, err := p.Reader.Read(buf)
lastProgressPercent := math.Floor(100.0 * float64(p.currentOffset) / float64(p.totalBytes))
nextProgressPercent := math.Floor(100.0 * (float64(p.currentOffset) + float64(n)) / float64(p.totalBytes))
if p.totalBytes > 0 && nextProgressPercent != lastProgressPercent {
p.progressFunc(nextProgressPercent)
}
p.currentOffset += int64(n)
return n, err
}