move some io related utils to pkg/ioutils
Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)
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3 changed files with 139 additions and 0 deletions
82
ioutils/readers.go
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82
ioutils/readers.go
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package ioutils
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import (
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"bytes"
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"io"
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"sync"
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)
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type readCloserWrapper struct {
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io.Reader
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closer func() error
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}
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func (r *readCloserWrapper) Close() error {
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return r.closer()
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}
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func NewReadCloserWrapper(r io.Reader, closer func() error) io.ReadCloser {
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return &readCloserWrapper{
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Reader: r,
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closer: closer,
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}
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}
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type bufReader struct {
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sync.Mutex
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buf *bytes.Buffer
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reader io.Reader
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err error
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wait sync.Cond
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}
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func NewBufReader(r io.Reader) *bufReader {
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reader := &bufReader{
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buf: &bytes.Buffer{},
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reader: r,
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}
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reader.wait.L = &reader.Mutex
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go reader.drain()
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return reader
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}
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func (r *bufReader) drain() {
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buf := make([]byte, 1024)
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for {
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n, err := r.reader.Read(buf)
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r.Lock()
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if err != nil {
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r.err = err
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} else {
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r.buf.Write(buf[0:n])
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}
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r.wait.Signal()
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r.Unlock()
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if err != nil {
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break
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}
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}
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}
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func (r *bufReader) Read(p []byte) (n int, err error) {
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r.Lock()
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defer r.Unlock()
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for {
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n, err = r.buf.Read(p)
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if n > 0 {
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return n, err
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}
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if r.err != nil {
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return 0, r.err
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}
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r.wait.Wait()
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}
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}
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func (r *bufReader) Close() error {
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closer, ok := r.reader.(io.ReadCloser)
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if !ok {
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return nil
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}
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return closer.Close()
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}
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34
ioutils/readers_test.go
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34
ioutils/readers_test.go
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package ioutils
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import (
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"bytes"
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"io"
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"io/ioutil"
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"testing"
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)
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func TestBufReader(t *testing.T) {
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reader, writer := io.Pipe()
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bufreader := NewBufReader(reader)
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// Write everything down to a Pipe
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// Usually, a pipe should block but because of the buffered reader,
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// the writes will go through
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done := make(chan bool)
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go func() {
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writer.Write([]byte("hello world"))
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writer.Close()
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done <- true
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}()
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// Drain the reader *after* everything has been written, just to verify
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// it is indeed buffering
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<-done
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output, err := ioutil.ReadAll(bufreader)
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if err != nil {
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t.Fatal(err)
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}
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if !bytes.Equal(output, []byte("hello world")) {
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t.Error(string(output))
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}
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}
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23
ioutils/writers.go
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23
ioutils/writers.go
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@ -0,0 +1,23 @@
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package ioutils
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import "io"
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type NopWriter struct{}
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func (*NopWriter) Write(buf []byte) (int, error) {
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return len(buf), nil
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}
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type nopWriteCloser struct {
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io.Writer
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}
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func (w *nopWriteCloser) Close() error { return nil }
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func NopWriteCloser(w io.Writer) io.WriteCloser {
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return &nopWriteCloser{w}
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}
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type NopFlusher struct{}
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func (f *NopFlusher) Flush() {}
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