Fixed JSONIndent request logging data race. (#775)

client_test.go

@@ -766,6 +766,29 @@ func TestLogCallbacks(t *testing.T) {
 	assertNotNil(t, resp)
 }
 
+func TestDebugLogSimultaneously(t *testing.T) {
+	ts := createGetServer(t)
+
+	c := New().
+		SetDebug(true).
+		SetBaseURL(ts.URL).
+		outputLogTo(io.Discard)
+
+	t.Cleanup(ts.Close)
+	for i := 0; i < 50; i++ {
+		t.Run(fmt.Sprint(i), func(t *testing.T) {
+			t.Parallel()
+			resp, err := c.R().
+				SetBody([]int{1, 2, 3}).
+				SetHeader(hdrContentTypeKey, "application/json; charset=utf-8").
+				Post("/")
+
+			assertError(t, err)
+			assertEqual(t, http.StatusOK, resp.StatusCode())
+		})
+	}
+}
+
 func TestNewWithLocalAddr(t *testing.T) {
 	ts := createGetServer(t)
 	defer ts.Close()

request.go

@@ -1014,7 +1014,12 @@ func (r *Request) fmtBodyString(sl int64) (body string) {
 	contentType := r.Header.Get(hdrContentTypeKey)
 	kind := kindOf(r.Body)
 	if canJSONMarshal(contentType, kind) {
-		prtBodyBytes, err = noescapeJSONMarshalIndent(&r.Body)
+		var bodyBuf *bytes.Buffer
+		bodyBuf, err = noescapeJSONMarshalIndent(&r.Body)
+		if err == nil {
+			prtBodyBytes = bodyBuf.Bytes()
+			defer releaseBuffer(bodyBuf)
+		}
 	} else if IsXMLType(contentType) && (kind == reflect.Struct) {
 		prtBodyBytes, err = xml.MarshalIndent(&r.Body, "", "   ")
 	} else if b, ok := r.Body.(string); ok {
@@ -1077,17 +1082,16 @@ var noescapeJSONMarshal = func(v interface{}) (*bytes.Buffer, error) {
 	return buf, nil
 }
 
-var noescapeJSONMarshalIndent = func(v interface{}) ([]byte, error) {
+var noescapeJSONMarshalIndent = func(v interface{}) (*bytes.Buffer, error) {
 	buf := acquireBuffer()
-	defer releaseBuffer(buf)
-
 	encoder := json.NewEncoder(buf)
 	encoder.SetEscapeHTML(false)
 	encoder.SetIndent("", "   ")
 
 	if err := encoder.Encode(v); err != nil {
+		releaseBuffer(buf)
 		return nil, err
 	}
 
-	return buf.Bytes(), nil
+	return buf, nil
 }