bufio: make the minimum read buffer size 16 bytes.

R=gri, rsc
CC=golang-dev
https://golang.org/cl/5485067

diff --git a/src/pkg/bufio/bufio.go b/src/pkg/bufio/bufio.go
index 61e338b61657519aeec1744f41fc7aff601ec03e..907a9dcb719aeddfa130c5fa74ec444049da7748 100644 (file)
--- a/src/pkg/bufio/bufio.go
+++ b/src/pkg/bufio/bufio.go
@@ -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?

diff --git a/src/pkg/bufio/bufio_test.go b/src/pkg/bufio/bufio_test.go
index 54029cd40fdd2e76a484344d588a1c68b25561c9..6463bbb9cb3fde048fae35db8fffcb64bf7b31c8 100644 (file)
--- a/src/pkg/bufio/bufio_test.go
+++ b/src/pkg/bufio/bufio_test.go
@@ -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)
@@ -715,34 +727,19 @@ type readLineResult struct {
 }
 
 var readLineNewlinesTests = []struct {
-       input   string
-       bufSize int
-       expect  []readLineResult
+       input  string
+       expect []readLineResult
 }{
-       {"h\r\nb\r\n", 2, []readLineResult{
-               {[]byte("h"), true, nil},
-               {nil, false, nil},
-               {[]byte("b"), true, nil},
-               {nil, false, nil},
-               {nil, false, io.EOF},
-       }},
-       {"hello\r\nworld\r\n", 6, []readLineResult{
-               {[]byte("hello"), true, nil},
+       {"012345678901234\r\n012345678901234\r\n", []readLineResult{
+               {[]byte("012345678901234"), true, nil},
                {nil, false, nil},
-               {[]byte("world"), true, nil},
+               {[]byte("012345678901234"), 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)
        }