Asynchronous persistence

Main5.java

private void persistSales(List<Sale> sales, final PersistenceComplete f) {
    if (!sales.isEmpty()) {
        LOGGER.info("preparing to persist sales");

        final AtomicInteger count = new AtomicInteger(sales.size());
        sales.forEach(sale -> {
            List values = Arrays.asList(sale.getBuyer().getName(), 
                                        sale.getSeller().getName(),
                                        sale.getProductId(),
                                        sale.getPrice(),
                                        sale.getQuantity(),
                                        sale.getPurchaseOrder().getId(),
                                        sale.getSalesOrder().getId());
            
            Future<QueryResult> sendQuery = POOL.sendPreparedStatement(SQL, JavaConversions.asScalaBuffer(values));
            sendQuery.onComplete(new JFunction1<Try<QueryResult>, Void>() {
                @Override
                public Void apply(Try<QueryResult> t) {
                    if(t.isSuccess()){
                        QueryResult qr = t.get();
                        //the query result doesnt contain auto generated IDs! library seems immature...
                        //sale.setId(???);
                    }
                    
                    if(count.decrementAndGet() == 0){
                        if(t.isSuccess()){
                            f.apply(null);
                        }else{
                            f.apply(t.failed().get());
                        }
                        
                    }
                    return null; //coz of Void
                }
            }, Main.system.dispatcher());
        });
    }else{
        f.apply(null); //nothing to do, so continue immediately
    }
}