api: unexport Stream fields, add Id() accessor

CHANGELOG.md

@@ -93,6 +93,9 @@ Versioning](http://semver.org/spec/v2.0.0.html) except to the first release.
   Use `Opts.Logger *slog.Logger` instead. Pool `Opts.Logger *slog.Logger`
   replaces direct `log.Printf` calls that were not customizable.
   By default, logs are discarded (silent). See MIGRATION.md for details.
+* `Stream` struct fields `Id` and `Conn` are now unexported, making `Stream`
+  an opaque handle. Neither the stream identifier nor the underlying
+  connection is reachable from outside the package (#471).
 
 ### Removed
 

MIGRATION.md

@@ -166,6 +166,22 @@ TODO
   `tarantool.pool` group. When a pool logger is set and a connection
   does not have its own logger, the pool passes its logger to each
   connection, which then applies its own `WithGroup("tarantool")`.
+* `Stream` struct fields `Id` and `Conn` are unexported, making `Stream` an
+  opaque handle. The stream identifier and the underlying connection are
+  internal details; callers should hold their own `*Connection` reference if
+  they need it.
+
+  Before:
+  ```go
+  stream, _ := conn.NewStream()
+  log.Printf("opened stream %d on %v", stream.Id, stream.Conn)
+  ```
+
+  After:
+  ```go
+  stream, _ := conn.NewStream()
+  log.Printf("opened stream on %v", conn)
+  ```
 
 ## Migration from v1.x.x to v2.x.x
 

connection.go

@@ -1296,8 +1296,8 @@ func (conn *Connection) NewPrepared(expr string) (*Prepared, error) {
 func (conn *Connection) NewStream() (*Stream, error) {
 	next := conn.lastStreamId.Add(1)
 	return &Stream{
-		Id:   next,
-		Conn: conn,
+		id:   next,
+		conn: conn,
 	}, nil
 }
 

stream.go

@@ -31,8 +31,8 @@ var (
 )
 
 type Stream struct {
-	Id   uint64
-	Conn *Connection
+	id   uint64
+	conn *Connection
 }
 
 // BeginRequest helps you to create a begin request object for execution
@@ -241,9 +241,9 @@ func (req *RollbackRequest) Context(ctx context.Context) *RollbackRequest {
 // create the future.
 func (s *Stream) Do(req Request) Future {
 	if connectedReq, ok := req.(ConnectedRequest); ok {
-		if connectedReq.Conn() != s.Conn {
+		if connectedReq.Conn() != s.conn {
 			return NewFutureWithErr(req, errUnknownStreamRequest)
 		}
 	}
-	return s.Conn.send(req, s.Id)
+	return s.conn.send(req, s.id)
 }

tarantool_test.go

@@ -7,7 +7,6 @@ import (
 	"io"
 	"log"
 	"log/slog"
-	"math"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -2089,36 +2088,6 @@ func TestComplexStructs(t *testing.T) {
 	assert.Equal(t, tuple.Members[1].Name, tuples[0].Members[1].Name)
 }
 
-func TestStream_IdValues(t *testing.T) {
-	test_helpers.SkipIfStreamsUnsupported(t)
-
-	conn := test_helpers.ConnectWithValidation(t, dialer, opts)
-	defer func() { _ = conn.Close() }()
-
-	cases := []uint64{
-		1,
-		128,
-		math.MaxUint8,
-		math.MaxUint8 + 1,
-		math.MaxUint16,
-		math.MaxUint16 + 1,
-		math.MaxUint32,
-		math.MaxUint32 + 1,
-		math.MaxUint64,
-	}
-
-	stream, _ := conn.NewStream()
-	req := NewPingRequest()
-
-	for _, id := range cases {
-		t.Run(fmt.Sprintf("%d", id), func(t *testing.T) {
-			stream.Id = id
-			_, err := stream.Do(req).Get()
-			require.NoError(t, err, "Failed to Ping")
-		})
-	}
-}
-
 func TestStream_Commit(t *testing.T) {
 	var req Request
 	var err error