util.go

// Copyright 2016 Gareth Watts
// Licensed under an MIT license
// See the LICENSE file for details

package main

import (
	"fmt"
	"io"
	"sync/atomic"
)

const (
	kib = 1 << 10
	mib = 1 << 20
	gib = 1 << 30
	tib = 1 << 40
)

func fmtBytes(bytes int64) string {
	switch {
	case bytes < 0:
		return "unknown"
	case bytes < kib:
		return fmt.Sprintf("%d bytes", bytes)
	case bytes < mib:
		return fmt.Sprintf("%.1f KB", float64(bytes)/kib)
	case bytes < gib:
		return fmt.Sprintf("%.1f MB", float64(bytes)/mib)
	case bytes < tib:
		return fmt.Sprintf("%.1f GB", float64(bytes)/gib)
	default:
		return fmt.Sprintf("%.1f TB", float64(bytes)/tib)
	}
}

type readWatcher struct {
	io.Reader
	bytesRead int64
}

func newReadWatcher(r io.Reader) *readWatcher {
	return &readWatcher{Reader: r}
}

func (r *readWatcher) Read(p []byte) (n int, err error) {
	n, err = r.Reader.Read(p)
	atomic.AddInt64(&r.bytesRead, int64(n))
	return n, err
}

func (r *readWatcher) BytesRead() int64 {
	return atomic.LoadInt64(&r.bytesRead)
}