Hibernate optimist locking code snippet #7

snippet.groovy

// Transactional service method
void addComment(Photo photo, String text) {
    def comment = new PhotoComment(text: text)
    comment.save()
    // We have to lock the parent here, or we will not prevent
    // background task changing things (as it happens the
    // changes do not overlap…)
    photo.lock()
    photo.addToComments(comment)        
}

// Asynchronous Quartz Job method
void uploadPhoto(Photo p) {
    // do something with S3
    // …
    // Create a new transaction so we don't hog the lock for
    // too long
    Photo.withTransaction { txn ->
        def photo = Photo.get(p.id)
        photo.lock()
        photo.url = newUrls
    }
}