ayylmao123xdd Posts - Answer Overflow

ayylmao123xdd

•Created by ayylmao123xdd on 10/24/2024 in #java-help

handling lost update problem happening with one thread updating a resource at a time

so i got this quite an interesting problem where i got a piece of code that edits a entity there is one class and a bunch of other classes that inherit it the superclass has a version field for optimistic locking all subclasses are stored in the same jpa repository the lost update/stale data problem comes when sending an update command example scenario employee gets updated salary to 3000 but the request will sent later employee gets updated salary to 5000 but the request is sent immediately so the employee gets 3000 salary even though he was supposed to have 5000 i was thinking of comparing the version of the entity and the version thats sent in the command but that generates race condition example code

    @Transactional
    public Dto edit(long id, EditCommand command) {
        try {
            Subclass subclass = repository.findWithLockingById(id)
                    .orElseThrow();
//            if (command.getVersion() != subclass.getVersion()) {
//            } generates race condition
            service.update(command, subclass);
            return mapper.mapToDto(subclass);
    }

    @Transactional
    public Dto edit(long id, EditCommand command) {
        try {
            Subclass subclass = repository.findWithLockingById(id)
                    .orElseThrow();
//            if (command.getVersion() != subclass.getVersion()) {
//            } generates race condition
            service.update(command, subclass);
            return mapper.mapToDto(subclass);
    }

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