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bufio: make the minimum read buffer size 16 bytes.

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R=gri, rsc
CC=golang-dev
https://golang.org/cl/5485067
This commit is contained in:
Rob Pike 2011-12-13 15:07:17 -08:00
parent 5fe96c640a
commit 64776da456
2 changed files with 50 additions and 51 deletions
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6
src/pkg/bufio/bufio.go
View File

@ -52,12 +52,14 @@ type Reader struct {
lastRuneSize int
}
const minReadBufferSize = 16
// NewReaderSize creates a new Reader whose buffer has the specified size,
// which must be greater than one. If the argument io.Reader is already a
// which must be at least 16 bytes. If the argument io.Reader is already a
// Reader with large enough size, it returns the underlying Reader.
// It returns the Reader and any error.
func NewReaderSize(rd io.Reader, size int) (*Reader, error) {
if size <= 1 {
if size < minReadBufferSize {
return nil, BufSizeError(size)
}
// Is it already a Reader?

91
src/pkg/bufio/bufio_test.go
View File

@ -135,9 +135,10 @@ var bufreaders = []bufReader{
{"lines", readLines},
}
const minReadBufferSize = 16
var bufsizes = []int{
2, 3, 4, 5, 6, 7, 8, 9, 10,
23, 32, 46, 64, 93, 128, 1024, 4096,
minReadBufferSize, 23, 32, 46, 64, 93, 128, 1024, 4096,
}
func TestReader(t *testing.T) {
@ -514,27 +515,32 @@ func TestWriteString(t *testing.T) {
}
func TestBufferFull(t *testing.T) {
buf, _ := NewReaderSize(strings.NewReader("hello, world"), 5)
line, err := buf.ReadSlice(',')
if string(line) != "hello" || err != ErrBufferFull {
const longString = "And now, hello, world! It is the time for all good men to come to the aid of their party"
buf, err := NewReaderSize(strings.NewReader(longString), minReadBufferSize)
if err != nil {
t.Fatal("NewReaderSize:", err)
}
line, err := buf.ReadSlice('!')
if string(line) != "And now, hello, " || err != ErrBufferFull {
t.Errorf("first ReadSlice(,) = %q, %v", line, err)
}
line, err = buf.ReadSlice(',')
if string(line) != "," || err != nil {
line, err = buf.ReadSlice('!')
if string(line) != "world!" || err != nil {
t.Errorf("second ReadSlice(,) = %q, %v", line, err)
}
}
func TestPeek(t *testing.T) {
p := make([]byte, 10)
buf, _ := NewReaderSize(strings.NewReader("abcdefghij"), 4)
// string is 16 (minReadBufferSize) long.
buf, _ := NewReaderSize(strings.NewReader("abcdefghijklmnop"), minReadBufferSize)
if s, err := buf.Peek(1); string(s) != "a" || err != nil {
t.Fatalf("want %q got %q, err=%v", "a", string(s), err)
}
if s, err := buf.Peek(4); string(s) != "abcd" || err != nil {
t.Fatalf("want %q got %q, err=%v", "abcd", string(s), err)
}
if _, err := buf.Peek(5); err != ErrBufferFull {
if _, err := buf.Peek(32); err != ErrBufferFull {
t.Fatalf("want ErrBufFull got %v", err)
}
if _, err := buf.Read(p[0:3]); string(p[0:3]) != "abc" || err != nil {
@ -552,8 +558,8 @@ func TestPeek(t *testing.T) {
if s, err := buf.Peek(4); string(s) != "ghij" || err != nil {
t.Fatalf("want %q got %q, err=%v", "ghij", string(s), err)
}
if _, err := buf.Read(p[0:4]); string(p[0:4]) != "ghij" || err != nil {
t.Fatalf("want %q got %q, err=%v", "ghij", string(p[0:3]), err)
if _, err := buf.Read(p[0:]); string(p[0:]) != "ghijklmnop" || err != nil {
t.Fatalf("want %q got %q, err=%v", "ghijklmnop", string(p[0:minReadBufferSize]), err)
}
if s, err := buf.Peek(0); string(s) != "" || err != nil {
t.Fatalf("want %q got %q, err=%v", "", string(s), err)
@ -635,19 +641,25 @@ func TestReadLine(t *testing.T) {
}
func TestLineTooLong(t *testing.T) {
buf := bytes.NewBuffer([]byte("aaabbbcc\n"))
l, _ := NewReaderSize(buf, 3)
data := make([]byte, 0)
for i := 0; i < minReadBufferSize*5/2; i++ {
data = append(data, '0'+byte(i%10))
}
buf := bytes.NewBuffer(data)
l, _ := NewReaderSize(buf, minReadBufferSize)
line, isPrefix, err := l.ReadLine()
if !isPrefix || !bytes.Equal(line, []byte("aaa")) || err != nil {
t.Errorf("bad result for first line: %x %s", line, err)
if !isPrefix || !bytes.Equal(line, data[:minReadBufferSize]) || err != nil {
t.Errorf("bad result for first line: got %q want %q %v", line, data[:minReadBufferSize], err)
}
data = data[len(line):]
line, isPrefix, err = l.ReadLine()
if !isPrefix || !bytes.Equal(line, []byte("bbb")) || err != nil {
t.Errorf("bad result for second line: %x", line)
if !isPrefix || !bytes.Equal(line, data[:minReadBufferSize]) || err != nil {
t.Errorf("bad result for second line: got %q want %q %v", line, data[:minReadBufferSize], err)
}
data = data[len(line):]
line, isPrefix, err = l.ReadLine()
if isPrefix || !bytes.Equal(line, []byte("cc")) || err != nil {
t.Errorf("bad result for third line: %x", line)
if isPrefix || !bytes.Equal(line, data[:minReadBufferSize/2]) || err != nil {
t.Errorf("bad result for third line: got %q want %q %v", line, data[:minReadBufferSize/2], err)
}
line, isPrefix, err = l.ReadLine()
if isPrefix || err == nil {
@ -656,8 +668,8 @@ func TestLineTooLong(t *testing.T) {
}
func TestReadAfterLines(t *testing.T) {
line1 := "line1"
restData := "line2\nline 3\n"
line1 := "this is line1"
restData := "this is line2\nthis is line 3\n"
inbuf := bytes.NewBuffer([]byte(line1 + "\n" + restData))
outbuf := new(bytes.Buffer)
maxLineLength := len(line1) + len(restData)/2
@ -676,7 +688,7 @@ func TestReadAfterLines(t *testing.T) {
}
func TestReadEmptyBuffer(t *testing.T) {
l, _ := NewReaderSize(bytes.NewBuffer(nil), 10)
l, _ := NewReaderSize(bytes.NewBuffer(nil), minReadBufferSize)
line, isPrefix, err := l.ReadLine()
if err != io.EOF {
t.Errorf("expected EOF from ReadLine, got '%s' %t %s", line, isPrefix, err)
@ -684,7 +696,7 @@ func TestReadEmptyBuffer(t *testing.T) {
}
func TestLinesAfterRead(t *testing.T) {
l, _ := NewReaderSize(bytes.NewBuffer([]byte("foo")), 10)
l, _ := NewReaderSize(bytes.NewBuffer([]byte("foo")), minReadBufferSize)
_, err := ioutil.ReadAll(l)
if err != nil {
t.Error(err)
@ -716,33 +728,18 @@ type readLineResult struct {
var readLineNewlinesTests = []struct {
input string
bufSize int
expect []readLineResult
}{
{"h\r\nb\r\n", 2, []readLineResult{
{[]byte("h"), true, nil},
{"012345678901234\r\n012345678901234\r\n", []readLineResult{
{[]byte("012345678901234"), true, nil},
{nil, false, nil},
{[]byte("b"), true, nil},
{[]byte("012345678901234"), true, nil},
{nil, false, nil},
{nil, false, io.EOF},
}},
{"hello\r\nworld\r\n", 6, []readLineResult{
{[]byte("hello"), true, nil},
{nil, false, nil},
{[]byte("world"), true, nil},
{nil, false, nil},
{nil, false, io.EOF},
}},
{"hello\rworld\r", 6, []readLineResult{
{[]byte("hello"), true, nil},
{[]byte("\rworld"), true, nil},
{[]byte("\r"), false, nil},
{nil, false, io.EOF},
}},
{"h\ri\r\n\r", 2, []readLineResult{
{[]byte("h"), true, nil},
{[]byte("\ri"), true, nil},
{nil, false, nil},
{"0123456789012345\r012345678901234\r", []readLineResult{
{[]byte("0123456789012345"), true, nil},
{[]byte("\r012345678901234"), true, nil},
{[]byte("\r"), false, nil},
{nil, false, io.EOF},
}},
@ -750,12 +747,12 @@ var readLineNewlinesTests = []struct {
func TestReadLineNewlines(t *testing.T) {
for _, e := range readLineNewlinesTests {
testReadLineNewlines(t, e.input, e.bufSize, e.expect)
testReadLineNewlines(t, e.input, e.expect)
}
}
func testReadLineNewlines(t *testing.T, input string, bufSize int, expect []readLineResult) {
b, err := NewReaderSize(strings.NewReader(input), bufSize)
func testReadLineNewlines(t *testing.T, input string, expect []readLineResult) {
b, err := NewReaderSize(strings.NewReader(input), minReadBufferSize)
if err != nil {
t.Fatal(err)
}