api: allow Future.GetTyped() after Future.Get()

After the patch, a user can call Future.GetTyped() after Future.Get(). It can be useful at least after receiving push messages. Needed for tarantool/tt#54

Author: oleg-jukovec

CHANGELOG.md

@@ -25,6 +25,8 @@ Versioning](http://semver.org/spec/v2.0.0.html) except to the first release.
 - Addresses in ConnectionPool may be changed from an external code (#208)
 - ConnectionPool recreates connections too often (#208)
 - A connection is still opened after ConnectionPool.Close() (#208)
+- Future.GetTyped() after Future.Get() does not decode response
+ correctly (#213)
 
 ## [1.8.0] - 2022-08-17
 

response.go

@@ -144,6 +144,9 @@ func (resp *Response) decodeHeader(d *decoder) (err error) {
 
 func (resp *Response) decodeBody() (err error) {
 if resp.buf.Len() > 2 {
+offset := resp.buf.Offset()
+defer resp.buf.Seek(offset)
+
 var l int
 var stmtID, bindCount uint64
 
@@ -211,6 +214,9 @@ func (resp *Response) decodeBody() (err error) {
 
 func (resp *Response) decodeBodyTyped(res interface{}) (err error) {
 if resp.buf.Len() > 0 {
+offset := resp.buf.Offset()
+defer resp.buf.Seek(offset)
+
 var l int
 d := newDecoder(&resp.buf)
 if l, err = d.DecodeMapLen(); err != nil {

smallbuf.go

@@ -51,6 +51,21 @@ func (s *smallBuf) Bytes() []byte {
 return nil
 }
 
+func (s *smallBuf) Offset() int {
+return s.p
+}
+
+func (s *smallBuf) Seek(offset int) error {
+if offset < 0 {
+return errors.New("too small offset")
+}
+if offset > len(s.b) {
+return errors.New("too big offset")
+}
+s.p = offset
+return nil
+}
+
 type smallWBuf struct {
 b []byte
 sum uint

tarantool_test.go

@@ -721,6 +721,44 @@ func BenchmarkSQLSerial(b *testing.B) {
 }
 }
 
+func TestFutMultipleGetGetTyped(t *testing.T) {
+conn := test_helpers.ConnectWithValidation(t, server, opts)
+defer conn.Close()
+
+fut := conn.Call17Async("simple_concat", []interface{}{"1"})
+
+for i := 0; i < 30; i++ {
+// [0, 10) fut.Get()
+// [10, 20) fut.GetTyped()
+// [20, 30) Mix
+get := false
+if (i < 10) || (i >= 20 && i%2 == 0) {
+get = true
+}
+
+if get {
+resp, err := fut.Get()
+if err != nil {
+t.Errorf("Failed to call Get(): %s", err)
+}
+if val, ok := resp.Data[0].(string); !ok || val != "11" {
+t.Errorf("Wrong Get() result: %v", resp.Data)
+}
+} else {
+tpl := struct {
+Val string
+}{}
+err := fut.GetTyped(&tpl)
+if err != nil {
+t.Errorf("Failed to call GetTyped(): %s", err)
+}
+if tpl.Val != "11" {
+t.Errorf("Wrong GetTyped() result: %v", tpl)
+}
+}
+}
+}
+
 ///////////////////
 
 func TestClient(t *testing.T) {
@@ -1069,7 +1107,7 @@ func TestClientSessionPush(t *testing.T) {
 } else if len(resp.Data) < 1 {
 t.Errorf("Response.Data is empty after Call17Async")
 } else if val, err := convertUint64(resp.Data[0]); err != nil || val != pushMax {
-t.Errorf("result is not {{1}} : %v", resp.Data)
+t.Errorf("Result is not %d: %v", pushMax, resp.Data)
 }
 
 // It will will be iterated with a timeout.
@@ -1103,7 +1141,7 @@ func TestClientSessionPush(t *testing.T) {
 } else {
 respCnt += 1
 if val, err := convertUint64(resp.Data[0]); err != nil || val != pushMax {
-t.Errorf("result is not {{1}} : %v", resp.Data)
+t.Errorf("Result is not %d: %v", pushMax, resp.Data)
 }
 }
 }
@@ -1120,6 +1158,26 @@ func TestClientSessionPush(t *testing.T) {
 t.Errorf("Expect %d responses but got %d", 1, respCnt)
 }
 }
+
+// We can collect original responses after iterations.
+for _, fut := range []*Future{fut0, fut1, fut2} {
+resp, err := fut.Get()
+if err != nil {
+t.Errorf("Unable to call fut.Get(): %s", err)
+} else if val, err := convertUint64(resp.Data[0]); err != nil || val != pushMax {
+t.Errorf("Result is not %d: %v", pushMax, resp.Data)
+}
+
+tpl := struct {
+Val int
+}{}
+err = fut.GetTyped(&tpl)
+if err != nil {
+t.Errorf("Unable to call fut.GetTyped(): %s", err)
+} else if tpl.Val != pushMax {
+t.Errorf("Result is not %d: %d", pushMax, tpl.Val)
+}
+}
 }
 
 const (