Implemented periodic ping to keep connection of transaction alive

main.go

@@ -32,15 +32,17 @@ type DB struct {
 
 // Open initialize a new db connection, need to import driver first, e.g:
 //
-//     import _ "github.com/go-sql-driver/mysql"
+//	import _ "github.com/go-sql-driver/mysql"
-//     func main() {
+//	func main() {
-//       db, err := gorm.Open("mysql", "user:password@/dbname?charset=utf8&parseTime=True&loc=Local")
+//	  db, err := gorm.Open("mysql", "user:password@/dbname?charset=utf8&parseTime=True&loc=Local")
-//     }
+//	}
+//
 // GORM has wrapped some drivers, for easier to remember driver's import path, so you could import the mysql driver with
-//    import _ "github.com/jinzhu/gorm/dialects/mysql"
+//
-//    // import _ "github.com/jinzhu/gorm/dialects/postgres"
+//	import _ "github.com/jinzhu/gorm/dialects/mysql"
-//    // import _ "github.com/jinzhu/gorm/dialects/sqlite"
+//	// import _ "github.com/jinzhu/gorm/dialects/postgres"
-//    // import _ "github.com/jinzhu/gorm/dialects/mssql"
+//	// import _ "github.com/jinzhu/gorm/dialects/sqlite"
+//	// import _ "github.com/jinzhu/gorm/dialects/mssql"
 func Open(dialect string, args ...interface{}) (db *DB, err error) {
 	if len(args) == 0 {
 		err = errors.New("invalid database source")
@@ -121,7 +123,9 @@ func (s *DB) Dialect() Dialect {
 }
 
 // Callback return `Callbacks` container, you could add/change/delete callbacks with it
-//     db.Callback().Create().Register("update_created_at", updateCreated)
+//
+//	db.Callback().Create().Register("update_created_at", updateCreated)
+//
 // Refer https://jinzhu.github.io/gorm/development.html#callbacks
 func (s *DB) Callback() *Callback {
 	s.parent.callbacks = s.parent.callbacks.clone()
@@ -224,9 +228,10 @@ func (s *DB) Offset(offset interface{}) *DB {
 }
 
 // Order specify order when retrieve records from database, set reorder to `true` to overwrite defined conditions
-//     db.Order("name DESC")
+//
-//     db.Order("name DESC", true) // reorder
+//	db.Order("name DESC")
-//     db.Order(gorm.Expr("name = ? DESC", "first")) // sql expression
+//	db.Order("name DESC", true) // reorder
+//	db.Order(gorm.Expr("name = ? DESC", "first")) // sql expression
 func (s *DB) Order(value interface{}, reorder ...bool) *DB {
 	return s.clone().search.Order(value, reorder...).db
 }
@@ -253,23 +258,26 @@ func (s *DB) Having(query interface{}, values ...interface{}) *DB {
 }
 
 // Joins specify Joins conditions
-//     db.Joins("JOIN emails ON emails.user_id = users.id AND emails.email = ?", "jinzhu@example.org").Find(&user)
+//
+//	db.Joins("JOIN emails ON emails.user_id = users.id AND emails.email = ?", "jinzhu@example.org").Find(&user)
 func (s *DB) Joins(query interface{}, args ...interface{}) *DB {
 	return s.clone().search.Joins(query, args...).db
 }
 
 // Scopes pass current database connection to arguments `func(*DB) *DB`, which could be used to add conditions dynamically
-//     func AmountGreaterThan1000(db *gorm.DB) *gorm.DB {
-//         return db.Where("amount > ?", 1000)
-//     }
 //
-//     func OrderStatus(status []string) func (db *gorm.DB) *gorm.DB {
+//	func AmountGreaterThan1000(db *gorm.DB) *gorm.DB {
-//         return func (db *gorm.DB) *gorm.DB {
+//	    return db.Where("amount > ?", 1000)
-//             return db.Scopes(AmountGreaterThan1000).Where("status in (?)", status)
+//	}
-//         }
+//
-//     }
+//	func OrderStatus(status []string) func (db *gorm.DB) *gorm.DB {
+//	    return func (db *gorm.DB) *gorm.DB {
+//	        return db.Scopes(AmountGreaterThan1000).Where("status in (?)", status)
+//	    }
+//	}
+//
+//	db.Scopes(AmountGreaterThan1000, OrderStatus([]string{"paid", "shipped"})).Find(&orders)
 //
-//     db.Scopes(AmountGreaterThan1000, OrderStatus([]string{"paid", "shipped"})).Find(&orders)
 // Refer https://jinzhu.github.io/gorm/crud.html#scopes
 func (s *DB) Scopes(funcs ...func(*DB) *DB) *DB {
 	for _, f := range funcs {
@@ -356,8 +364,9 @@ func (s *DB) ScanRows(rows *sql.Rows, result interface{}) error {
 }
 
 // Pluck used to query single column from a model as a map
-//     var ages []int64
+//
-//     db.Find(&users).Pluck("age", &ages)
+//	var ages []int64
+//	db.Find(&users).Pluck("age", &ages)
 func (s *DB) Pluck(column string, value interface{}) *DB {
 	return s.NewScope(s.Value).pluck(column, value).db
 }
@@ -454,7 +463,8 @@ func (s *DB) Delete(value interface{}, where ...interface{}) *DB {
 }
 
 // Raw use raw sql as conditions, won't run it unless invoked by other methods
-//    db.Raw("SELECT name, age FROM users WHERE name = ?", 3).Scan(&result)
+//
+//	db.Raw("SELECT name, age FROM users WHERE name = ?", 3).Scan(&result)
 func (s *DB) Raw(sql string, values ...interface{}) *DB {
 	return s.clone().search.Raw(true).Where(sql, values...).db
 }
@@ -469,10 +479,11 @@ func (s *DB) Exec(sql string, values ...interface{}) *DB {
 }
 
 // Model specify the model you would like to run db operations
-//    // update all users's name to `hello`
+//
-//    db.Model(&User{}).Update("name", "hello")
+//	// update all users's name to `hello`
-//    // if user's primary key is non-blank, will use it as condition, then will only update the user's name to `hello`
+//	db.Model(&User{}).Update("name", "hello")
-//    db.Model(&user).Update("name", "hello")
+//	// if user's primary key is non-blank, will use it as condition, then will only update the user's name to `hello`
+//	db.Model(&user).Update("name", "hello")
 func (s *DB) Model(value interface{}) *DB {
 	c := s.clone()
 	c.Value = value
@@ -530,32 +541,70 @@ func (s *DB) WrapInTx(f func(tx *DB) error) (err error) {
 	if _, ok := s.db.(*sql.Tx); ok {
 		// Already in a transaction
 		return f(s)
-	} else {
+	}
-		// Lets start a new transaction
+
-		tx := s.Begin()
+	// Lets start a new transaction
-		if err = tx.Error; err != nil {
+	tx := s.Begin()
-			return
+	if err = tx.Error; err != nil {
-		}
+		return err
-		panicked := true
+	}
-		defer func() {
+
-			if panicked || err != nil {
+	// Create a channel to stop the ping goroutine.
-				rollbackErr := tx.Rollback().Error
+	stopTxPing := make(chan bool)
-				if rollbackErr != nil {
+	// Start a goroutine that pings the database connection for a keep-alive.
-					if err == nil {
+	go func() {
-						err = rollbackErr
+		for {
-					} else {
+			select {
-						err = fmt.Errorf("Transacton code and rollback failed: %s; %s", err, rollbackErr)
+			// Stop the goroutine when the stop channel receives a value ..
-					}
+			case <-stopTxPing:
+				return
+			// .. otherwise ping the database connection every 10 seconds.
+			case <-time.After(10 * time.Second):
+				err := tx.DB().Ping()
+				if err != nil {
+					tx.AddError(
+						fmt.Errorf(
+							"Could not ping database connection for transaction: %w",
+							err,
+						),
+					)
+
+					return
 				}
 			}
-		}()
-		err = f(tx)
-		if err == nil {
-			err = tx.Commit().Error
 		}
-		panicked = false
+	}()
-		return
+
+	panicked := true
+
+	defer func() {
+		if panicked || err != nil {
+			rollbackErr := tx.Rollback().Error
+			if rollbackErr != nil {
+				if err == nil {
+					err = rollbackErr
+				} else {
+					err = fmt.Errorf("Transacton code and rollback failed: %s; %s", err, rollbackErr)
+				}
+			}
+		}
+	}()
+
+	err = f(tx)
+
+	// As soon as the inner stack has returned, stop the ping goroutine. As the transaction will be
+	// only committed after this point, the ping would fail and the goroutine will exit.
+	stopTxPing <- true
+	// Last but not least, close the stop ping channel.
+	close(stopTxPing)
+
+	if err == nil {
+		err = tx.Commit().Error
 	}
+
+	panicked = false
+
+	return err
 }
 
 // SkipAssocSave disables saving of associations
@@ -674,7 +723,8 @@ func (s *DB) RemoveIndex(indexName string) *DB {
 }
 
 // AddForeignKey Add foreign key to the given scope, e.g:
-//     db.Model(&User{}).AddForeignKey("city_id", "cities(id)", "RESTRICT", "RESTRICT")
+//
+//	db.Model(&User{}).AddForeignKey("city_id", "cities(id)", "RESTRICT", "RESTRICT")
 func (s *DB) AddForeignKey(field string, dest string, onDelete string, onUpdate string) *DB {
 	scope := s.NewScope(s.Value)
 	scope.addForeignKey(field, dest, onDelete, onUpdate)
@@ -682,7 +732,8 @@ func (s *DB) AddForeignKey(field string, dest string, onDelete string, onUpdate
 }
 
 // RemoveForeignKey Remove foreign key from the given scope, e.g:
-//     db.Model(&User{}).RemoveForeignKey("city_id", "cities(id)")
+//
+//	db.Model(&User{}).RemoveForeignKey("city_id", "cities(id)")
 func (s *DB) RemoveForeignKey(field string, dest string) *DB {
 	scope := s.clone().NewScope(s.Value)
 	scope.removeForeignKey(field, dest)
@@ -712,7 +763,8 @@ func (s *DB) Association(column string) *Association {
 }
 
 // Preload preload associations with given conditions
-//    db.Preload("Orders", "state NOT IN (?)", "cancelled").Find(&users)
+//
+//	db.Preload("Orders", "state NOT IN (?)", "cancelled").Find(&users)
 func (s *DB) Preload(column string, conditions ...interface{}) *DB {
 	return s.clone().search.Preload(column, conditions...).db
 }