Prevent the same user from reserving the same book multiple times when concurrent requests hit the server at the exact same time.
Acceptance Criteria:
Implement service-level validation that checks for active reservations (not just unique constraint)
Use database-level locking or optimistic locking for reservation creation
Ensure atomic check-and-create operation for reservations
Handle concurrent reservation attempts gracefully
Technical Notes:
Since we're keeping historical reservations (EXPIRED/COMPLETED) in the table, we cannot rely solely on @UniqueConstraint. We need to check for active statuses (PENDING, READY_FOR_PICKUP) in the service layer with proper concurrency control.
Prevent the same user from reserving the same book multiple times when concurrent requests hit the server at the exact same time.
Acceptance Criteria:
Implement service-level validation that checks for active reservations (not just unique constraint)
Use database-level locking or optimistic locking for reservation creation
Ensure atomic check-and-create operation for reservations
Handle concurrent reservation attempts gracefully
Technical Notes:
Since we're keeping historical reservations (EXPIRED/COMPLETED) in the table, we cannot rely solely on @UniqueConstraint. We need to check for active statuses (PENDING, READY_FOR_PICKUP) in the service layer with proper concurrency control.