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feat: add row-level locking to LoadUserByID #187

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feat: add row-level locking to LoadUserByID #187

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feat: add row-level locking to LoadUserByID
SmilingPixel May 11, 2025
bb62782
Merge remote-tracking branch 'origin/main' into zx_lock_load_user_0511
SmilingPixel Jun 8, 2025
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9 changes: 8 additions & 1 deletion models/user.go
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@ import (
"github.com/opentreehole/go-common"
"github.com/rs/zerolog/log"
"gorm.io/gorm"
"gorm.io/gorm/clause"
)

type User struct {
Expand Down Expand Up @@ -181,9 +182,15 @@ func GetCurrLoginUser(c *fiber.Ctx) (*User, error) {
return user, err
}

// LoadUserByID load user from database.
// if user not found, create a new user with default config.
// This method starts a transaction and would add a lock on the user row, as soon as it starts to read.
func (user *User) LoadUserByID(userID int) error {
return DB.Transaction(func(tx *gorm.DB) error {
err := tx.Take(&user, userID).Error
// Lock it for update (SELECT ... FOR UPDATE),
// see [MySQL Official Manual](https://dev.mysql.com/doc/refman/8.4/en/innodb-locking-reads.html)
// We do the query on userID, which is the primary key, so the lock should be on the row.
err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).Take(&user, userID).Error
if err != nil {
if errors.Is(err, gorm.ErrRecordNotFound) {
// insert user if not found
Expand Down