github.com/ndau/noms@v1.0.5/go/util/progressreader/reader.go (about)

     1  // Copyright 2016 Attic Labs, Inc. All rights reserved.
     2  // Licensed under the Apache License, version 2.0:
     3  // http://www.apache.org/licenses/LICENSE-2.0
     4  
     5  // Package progressreader provides an io.Reader that reports progress to a callback
     6  package progressreader
     7  
     8  import (
     9  	"io"
    10  	"time"
    11  
    12  	"github.com/ndau/noms/go/util/status"
    13  )
    14  
    15  type Callback func(seen uint64)
    16  
    17  func New(inner io.Reader, cb Callback) io.Reader {
    18  	return &reader{inner, uint64(0), time.Time{}, cb}
    19  }
    20  
    21  type reader struct {
    22  	inner    io.Reader
    23  	seen     uint64
    24  	lastTime time.Time
    25  	cb       Callback
    26  }
    27  
    28  func (r *reader) Read(p []byte) (n int, err error) {
    29  	n, err = r.inner.Read(p)
    30  	r.seen += uint64(n)
    31  
    32  	if now := time.Now(); now.Sub(r.lastTime) >= status.Rate || err == io.EOF {
    33  		r.cb(r.seen)
    34  		r.lastTime = now
    35  	}
    36  	return
    37  }