fix(nested transaction): SavePoint SQL Statement not support in Prepared Statements

finisher_api.go

@@ -6,8 +6,6 @@ import (
 	"fmt"
 	"reflect"
 	"strings"
-	"sync"
-	"sync/atomic"
 
 	"gorm.io/gorm/clause"
 	"gorm.io/gorm/logger"
@@ -612,15 +610,6 @@ func (db *DB) Connection(fc func(tx *DB) error) (err error) {
 	return fc(tx)
 }
 
-var (
-	savepointIdx      int64
-	savepointNamePool = &sync.Pool{
-		New: func() interface{} {
-			return fmt.Sprintf("gorm_%d", atomic.AddInt64(&savepointIdx, 1))
-		},
-	}
-)
-
 // Transaction start a transaction as a block, return error will rollback, otherwise to commit. Transaction executes an
 // arbitrary number of commands in fc within a transaction. On success the changes are committed; if an error occurs
 // they are rolled back.
@@ -630,17 +619,14 @@ func (db *DB) Transaction(fc func(tx *DB) error, opts ...*sql.TxOptions) (err er
 	if committer, ok := db.Statement.ConnPool.(TxCommitter); ok && committer != nil {
 		// nested transaction
 		if !db.DisableNestedTransaction {
-			poolName := savepointNamePool.Get()
-			defer savepointNamePool.Put(poolName)
-			err = db.SavePoint(poolName.(string)).Error
+			err = db.SavePoint(fmt.Sprintf("sp%p", fc)).Error
 			if err != nil {
 				return
 			}
-
 			defer func() {
 				// Make sure to rollback when panic, Block error or Commit error
 				if panicked || err != nil {
-					db.RollbackTo(poolName.(string))
+					db.RollbackTo(fmt.Sprintf("sp%p", fc))
 				}
 			}()
 		}
@@ -721,7 +707,21 @@ func (db *DB) Rollback() *DB {
 
 func (db *DB) SavePoint(name string) *DB {
 	if savePointer, ok := db.Dialector.(SavePointerDialectorInterface); ok {
+		// close prepared statement, because SavePoint not support prepared statement.
+		// e.g. mysql8.0 doc: https://dev.mysql.com/doc/refman/8.0/en/sql-prepared-statements.html
+		var (
+			preparedStmtTx   *PreparedStmtTX
+			isPreparedStmtTx bool
+		)
+		// close prepared statement, because SavePoint not support prepared statement.
+		if preparedStmtTx, isPreparedStmtTx = db.Statement.ConnPool.(*PreparedStmtTX); isPreparedStmtTx {
+			db.Statement.ConnPool = preparedStmtTx.Tx
+		}
 		db.AddError(savePointer.SavePoint(db, name))
+		// restore prepared statement
+		if isPreparedStmtTx {
+			db.Statement.ConnPool = preparedStmtTx
+		}
 	} else {
 		db.AddError(ErrUnsupportedDriver)
 	}
@@ -730,7 +730,21 @@ func (db *DB) SavePoint(name string) *DB {
 
 func (db *DB) RollbackTo(name string) *DB {
 	if savePointer, ok := db.Dialector.(SavePointerDialectorInterface); ok {
+		// close prepared statement, because RollbackTo not support prepared statement.
+		// e.g. mysql8.0 doc: https://dev.mysql.com/doc/refman/8.0/en/sql-prepared-statements.html
+		var (
+			preparedStmtTx   *PreparedStmtTX
+			isPreparedStmtTx bool
+		)
+		// close prepared statement, because SavePoint not support prepared statement.
+		if preparedStmtTx, isPreparedStmtTx = db.Statement.ConnPool.(*PreparedStmtTX); isPreparedStmtTx {
+			db.Statement.ConnPool = preparedStmtTx.Tx
+		}
 		db.AddError(savePointer.RollbackTo(db, name))
+		// restore prepared statement
+		if isPreparedStmtTx {
+			db.Statement.ConnPool = preparedStmtTx
+		}
 	} else {
 		db.AddError(ErrUnsupportedDriver)
 	}

tests/transaction_test.go

@@ -57,6 +57,19 @@ func TestTransaction(t *testing.T) {
 	if err := DB.First(&User{}, "name = ?", "transaction-2").Error; err != nil {
 		t.Fatalf("Should be able to find committed record, but got %v", err)
 	}
+
+	t.Run("this is test nested transaction and prepareStmt coexist case", func(t *testing.T) {
+		// enable prepare statement
+		tx3 := DB.Session(&gorm.Session{PrepareStmt: true})
+		if err := tx3.Transaction(func(tx4 *gorm.DB) error {
+			// nested transaction
+			return tx4.Transaction(func(tx5 *gorm.DB) error {
+				return tx5.First(&User{}, "name = ?", "transaction-2").Error
+			})
+		}); err != nil {
+			t.Fatalf("prepare statement and nested transcation coexist" + err.Error())
+		}
+	})
 }
 
 func TestCancelTransaction(t *testing.T) {