transaction does not work

[????????]

I found some problems when I tried to use ignite transactions.
I expected that the transaction would commit alfter tx.commit();
but when I debugged my code step by step , changes had been already in effect 
before tx.commit();?? 
I also tried reading some source code of ignite transactions, but found no 
answer??
I guess I must make a stupid mistake.


Here is my code.


 public static void withTransaction(Execute execute) throws Exception {
        try (Transaction tx = Ignition.ignite().transactions().txStart()) {
            execute.call();
            tx.commit();
        }
    }


public void call() throws Exception {
                    Area area = new Area();
                    area.cityId = 1l;
                    area.name = "test";
                    ??
                    cache.put(entity.id, entity);
                    ??
}