Cap the amount of buffering done by BytesPipe

Turn BytesPipe's Read and Write functions into blocking, goroutine-safe
functions. Add a CloseWithError function to propagate an error code to
the Read function.

Adjust tests to work with the blocking Read and Write functions.

Remove BufReader, since now its users can use BytesPipe directly.

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>

ioutils/readers_test.go

@@ -1,13 +1,9 @@
 package ioutils
 
 import (
-	"bytes"
 	"fmt"
-	"io"
-	"io/ioutil"
 	"strings"
 	"testing"
-	"time"
 )
 
 // Implement io.Reader
@@ -58,101 +54,6 @@ func TestReaderErrWrapperRead(t *testing.T) {
 	}
 }
 
-func TestNewBufReaderWithDrainbufAndBuffer(t *testing.T) {
-	reader, writer := io.Pipe()
-
-	drainBuffer := make([]byte, 1024)
-	buffer := NewBytesPipe(nil)
-	bufreader := NewBufReaderWithDrainbufAndBuffer(reader, drainBuffer, buffer)
-
-	// Write everything down to a Pipe
-	// Usually, a pipe should block but because of the buffered reader,
-	// the writes will go through
-	done := make(chan bool)
-	go func() {
-		writer.Write([]byte("hello world"))
-		writer.Close()
-		done <- true
-	}()
-
-	// Drain the reader *after* everything has been written, just to verify
-	// it is indeed buffering
-	select {
-	case <-done:
-	case <-time.After(1 * time.Second):
-		t.Fatal("timeout")
-	}
-
-	output, err := ioutil.ReadAll(bufreader)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if !bytes.Equal(output, []byte("hello world")) {
-		t.Error(string(output))
-	}
-}
-
-func TestBufReader(t *testing.T) {
-	reader, writer := io.Pipe()
-	bufreader := NewBufReader(reader)
-
-	// Write everything down to a Pipe
-	// Usually, a pipe should block but because of the buffered reader,
-	// the writes will go through
-	done := make(chan bool)
-	go func() {
-		writer.Write([]byte("hello world"))
-		writer.Close()
-		done <- true
-	}()
-
-	// Drain the reader *after* everything has been written, just to verify
-	// it is indeed buffering
-	<-done
-	output, err := ioutil.ReadAll(bufreader)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if !bytes.Equal(output, []byte("hello world")) {
-		t.Error(string(output))
-	}
-}
-
-func TestBufReaderCloseWithNonReaderCloser(t *testing.T) {
-	reader := strings.NewReader("buffer")
-	bufreader := NewBufReader(reader)
-
-	if err := bufreader.Close(); err != nil {
-		t.Fatal(err)
-	}
-
-}
-
-// implements io.ReadCloser
-type simpleReaderCloser struct {
-	err error
-}
-
-func (r *simpleReaderCloser) Read(p []byte) (n int, err error) {
-	return 0, r.err
-}
-
-func (r *simpleReaderCloser) Close() error {
-	r.err = io.EOF
-	return nil
-}
-
-func TestBufReaderCloseWithReaderCloser(t *testing.T) {
-	reader := &simpleReaderCloser{}
-	bufreader := NewBufReader(reader)
-
-	err := bufreader.Close()
-	if err != nil {
-		t.Fatal(err)
-	}
-
-}
-
 func TestHashData(t *testing.T) {
 	reader := strings.NewReader("hash-me")
 	actual, err := HashData(reader)
@@ -164,61 +65,3 @@ func TestHashData(t *testing.T) {
 		t.Fatalf("Expecting %s, got %s", expected, actual)
 	}
 }
-
-type repeatedReader struct {
-	readCount int
-	maxReads  int
-	data      []byte
-}
-
-func newRepeatedReader(max int, data []byte) *repeatedReader {
-	return &repeatedReader{0, max, data}
-}
-
-func (r *repeatedReader) Read(p []byte) (int, error) {
-	if r.readCount >= r.maxReads {
-		return 0, io.EOF
-	}
-	r.readCount++
-	n := copy(p, r.data)
-	return n, nil
-}
-
-func testWithData(data []byte, reads int) {
-	reader := newRepeatedReader(reads, data)
-	bufReader := NewBufReader(reader)
-	io.Copy(ioutil.Discard, bufReader)
-}
-
-func Benchmark1M10BytesReads(b *testing.B) {
-	reads := 1000000
-	readSize := int64(10)
-	data := make([]byte, readSize)
-	b.SetBytes(readSize * int64(reads))
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		testWithData(data, reads)
-	}
-}
-
-func Benchmark1M1024BytesReads(b *testing.B) {
-	reads := 1000000
-	readSize := int64(1024)
-	data := make([]byte, readSize)
-	b.SetBytes(readSize * int64(reads))
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		testWithData(data, reads)
-	}
-}
-
-func Benchmark10k32KBytesReads(b *testing.B) {
-	reads := 10000
-	readSize := int64(32 * 1024)
-	data := make([]byte, readSize)
-	b.SetBytes(readSize * int64(reads))
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		testWithData(data, reads)
-	}
-}