diff options
Diffstat (limited to 'pkg/database/locks.go')
-rw-r--r-- | pkg/database/locks.go | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/pkg/database/locks.go b/pkg/database/locks.go new file mode 100644 index 0000000..53c6f6e --- /dev/null +++ b/pkg/database/locks.go @@ -0,0 +1,50 @@ +package database + +import ( + "encoding/json" +) + +// Atomically check if there is an existing lock in place on the state. Returns +// true if it can be set, otherwise returns false and lock is set to the value +// of the existing lock +func (db *DB) SetLockOrGetExistingLock(name string, lock any) (bool, error) { + tx, err := db.Begin() + if err != nil { + return false, err + } + defer func() { + if err != nil { + _ = tx.Rollback() + } + }() + var data []byte + if err = tx.QueryRowContext(db.ctx, `SELECT lock FROM states WHERE name = ?;`, name).Scan(&data); err != nil { + return false, err + } + if data != nil { + err = json.Unmarshal(data, lock) + return false, err + } + if data, err = json.Marshal(lock); err != nil { + return false, err + } + _, err = tx.Exec(`UPDATE states SET lock = json(?) WHERE name = ?;`, data, name) + if err != nil { + return false, err + } + err = tx.Commit() + return true, err +} + +func (db *DB) Unlock(name, lock any) (bool, error) { + data, err := json.Marshal(lock) + if err != nil { + return false, err + } + result, err := db.Exec(`UPDATE states SET lock = NULL WHERE name = ? and lock = json(?);`, name, data) + if err != nil { + return false, err + } + n, err := result.RowsAffected() + return n == 1, err +} |