feat: allow GetBytes to get all bytes

nocopy_linkbuffer.go

@@ -557,8 +557,17 @@ func (b *LinkBuffer) Bytes() []byte {
 }
 
 // GetBytes will read and fill the slice p as much as possible.
+// If p is not passed, return all readable bytes.
 func (b *LinkBuffer) GetBytes(p [][]byte) (vs [][]byte) {
 	node, flush := b.read, b.flush
+	if len(p) == 0 {
+		n := 0
+		for ; node != flush; node = node.next {
+			n++
+		}
+		node = b.read
+		p = make([][]byte, n)
+	}
 	var i int
 	for i = 0; node != flush && i < len(p); node = node.next {
 		if node.Len() > 0 {

nocopy_linkbuffer_test.go

@@ -84,6 +84,31 @@ func TestLinkBuffer(t *testing.T) {
 	Equal(t, buf.Len(), 100)
 }
 
+func TestGetBytes(t *testing.T) {
+	buf := NewLinkBuffer()
+	var (
+		num         = 10
+		b           = 1
+		expectedLen = 0
+	)
+	for i := 0; i < num; i++ {
+		expectedLen += b
+		n, err := buf.WriteBinary(make([]byte, b))
+		MustNil(t, err)
+		Equal(t, n, b)
+		b *= 10
+	}
+	buf.Flush()
+	Equal(t, int(buf.length), expectedLen)
+	bs := buf.GetBytes(nil)
+	actualLen := 0
+	for i := 0; i < len(bs); i++ {
+		actualLen += len(bs[i])
+	}
+	Equal(t, actualLen, expectedLen)
+
+}
+
 // TestLinkBufferWithZero test more case with n is invalid.
 func TestLinkBufferWithInvalid(t *testing.T) {
 	// clean & new