tailscale/util/progresstracking/progresstracking.go

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// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// Package progresstracking provides wrappers around io.Reader and io.Writer
// that track progress.
package progresstracking
import (
"io"
"time"
)
// NewReader wraps the given Reader with a progress tracking Reader that
// reports progress at the following points:
//
// - First read
// - Every read spaced at least interval since the prior read
// - Last read
func NewReader(r io.Reader, interval time.Duration, onProgress func(totalRead int, err error)) io.Reader {
return &reader{Reader: r, interval: interval, onProgress: onProgress}
}
type reader struct {
io.Reader
interval time.Duration
onProgress func(int, error)
lastTracked time.Time
totalRead int
}
func (r *reader) Read(p []byte) (int, error) {
n, err := r.Reader.Read(p)
r.totalRead += n
if time.Since(r.lastTracked) > r.interval || err != nil {
r.onProgress(r.totalRead, err)
r.lastTracked = time.Now()
}
return n, err
}