readerutil

Documentation

Overview

Package readerutil provides and operates on io.Readers.

Package readerutil contains io.Reader types.

Index

• func NewBufferingReaderAt(r io.Reader) io.ReaderAt
• func NewFakeSeeker(r io.Reader, size int64) io.ReadSeeker
• func NewStatsReadSeeker(v *expvar.Int, rs io.ReadSeeker) io.ReadSeeker
• func NewStatsReader(v *expvar.Int, r io.Reader) io.Reader
• func Size(r io.Reader) (size int64, ok bool)
• type CountingReader
  • func (cr CountingReader) Read(p []byte) (n int, err error)
• type ReadSeekCloser
• type ReaderAtCloser
• type SizeReaderAt
  • func NewMultiReaderAt(parts ...SizeReaderAt) SizeReaderAt

Examples

• NewStatsReader

Functions

func NewBufferingReaderAt

func NewBufferingReaderAt(r io.Reader) io.ReaderAt

NewBufferingReaderAt returns an io.ReaderAt that reads from r as necessary and keeps a copy of all data read in memory.

func NewFakeSeeker

func NewFakeSeeker(r io.Reader, size int64) io.ReadSeeker

NewFakeSeeker returns a ReadSeeker that can pretend to Seek (based on the provided total size of the reader's content), but any reads will fail if the fake seek position doesn't match reality.

func NewStatsReadSeeker

func NewStatsReadSeeker(v *expvar.Int, rs io.ReadSeeker) io.ReadSeeker

NewStatsReadSeeker returns an io.ReadSeeker that will have the number of bytes read from rs added to v.

func NewStatsReader

func NewStatsReader(v *expvar.Int, r io.Reader) io.Reader

NewStatsReader returns an io.Reader that will have the number of bytes read from r added to v.

Example

var (
	// r is the io.Reader we'd like to count read from.
	r  = strings.NewReader("Hello world")
	v  = expvar.NewInt("read-bytes")
	sw = NewStatsReader(v, r)
)
// Read from the wrapped io.Reader, StatReader will count the bytes.
io.Copy(ioutil.Discard, sw)
fmt.Printf("Read %s bytes\n", v.String())

Output:

Read 11 bytes

func Size

func Size(r io.Reader) (size int64, ok bool)

Size tries to determine the length of r. If r is an io.Seeker, Size may seek to guess the length.

Types

type CountingReader

type CountingReader struct {
	Reader io.Reader
	N      *int64
}

CountingReader wraps a Reader, incrementing N by the number of bytes read. No locking is performed.

func (CountingReader) Read

func (cr CountingReader) Read(p []byte) (n int, err error)

type ReadSeekCloser

type ReadSeekCloser interface {
	io.Reader
	io.Seeker
	io.Closer
}

A ReadSeekCloser can Read, Seek, and Close.

type ReaderAtCloser

type ReaderAtCloser interface {
	io.ReaderAt
	io.Closer
}

type SizeReaderAt

type SizeReaderAt interface {
	Size() int64
	io.ReaderAt
}

A SizeReaderAt is a ReaderAt with a Size method.

An io.SectionReader implements SizeReaderAt.

func NewMultiReaderAt

func NewMultiReaderAt(parts ...SizeReaderAt) SizeReaderAt

NewMultiReaderAt is like io.MultiReader but produces a ReaderAt (and Size), instead of just a reader.