refactoring of xsql.conn.checkClosed + add TestRegressionCloud109307

Author: asmyasnikov

internal/xsql/badconn/badconn_go1.18.go

@@ -41,6 +41,8 @@ func (e Error) As(target interface{}) bool {
 
 func Map(err error) error {
 	switch {
+	case err == nil:
+		return nil
 	case xerrors.Is(err, driver.ErrBadConn):
 		return err
 	case retry.MustDeleteSession(err):

internal/xsql/conn.go

@@ -95,12 +95,6 @@ func newConn(c *Connector, s table.ClosableSession, opts ...connOption) *conn {
 }
 
 func (c *conn) checkClosed(err error) error {
-	if c.isClosed() {
-		return errClosedConn
-	}
-	if err == nil {
-		return nil
-	}
 	if err = badconn.Map(err); xerrors.Is(err, driver.ErrBadConn) {
 		c.setClosed()
 	}

sql_e2e_test.go

@@ -7,14 +7,20 @@ import (
 	"bytes"
 	"context"
 	"database/sql"
+	"errors"
 	"fmt"
+	"math/rand"
 	"os"
 	"path"
 	"testing"
 	"text/template"
 	"time"
 
+	"github.com/ydb-platform/ydb-go-genproto/protos/Ydb"
+
 	"github.com/ydb-platform/ydb-go-sdk/v3"
+	"github.com/ydb-platform/ydb-go-sdk/v3/internal/xerrors"
+	"github.com/ydb-platform/ydb-go-sdk/v3/internal/xsql/badconn"
 	"github.com/ydb-platform/ydb-go-sdk/v3/retry"
 	"github.com/ydb-platform/ydb-go-sdk/v3/sugar"
 	"github.com/ydb-platform/ydb-go-sdk/v3/table/types"
@@ -555,3 +561,56 @@ func render(t *template.Template, data interface{}) string {
 	}
 	return buf.String()
 }
+
+func TestRegressionCloud109307(t *testing.T) {
+	db, err := sql.Open("ydb", os.Getenv("YDB_CONNECTION_STRING"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 42*time.Second)
+	defer cancel()
+
+	for i := int64(1); ; i++ {
+		if ctx.Err() != nil {
+			break
+		}
+
+		if err = retry.DoTx(ctx, db, func(ctx context.Context, tx *sql.Tx) error {
+			//nolint:gosec
+			if rand.Int31n(3) == 0 {
+				return badconn.Map(xerrors.Operation(xerrors.WithStatusCode(Ydb.StatusIds_BAD_SESSION)))
+			}
+			var rows *sql.Rows
+			rows, err = tx.QueryContext(ctx, `
+				DECLARE $i AS Int64;
+
+				SELECT $i;
+			`, sql.Named("i", i))
+			if err != nil {
+				return err
+			}
+			defer rows.Close()
+			if !rows.Next() {
+				return errors.New("no rows")
+			}
+			var result interface{}
+			if err = rows.Scan(&result); err != nil {
+				return err
+			}
+			if result.(int64)%100 == 0 {
+				t.Logf("result: %+v\n", result)
+			}
+			return rows.Err()
+		}, retry.WithTxOptions(&sql.TxOptions{
+			Isolation: sql.LevelSnapshot,
+			ReadOnly:  true,
+		}), retry.WithDoTxRetryOptions(
+			retry.WithIdempotent(true),
+		)); err != nil {
+			if ctx.Err() == nil {
+				t.Fatalf("error: %+v\n", err)
+			}
+		}
+	}
+}