Examples with SerializableTransactionRunner org.jdbi.v3.core.transaction.SerializableTransactionRunner used on opensource projects

Example 1 with SerializableTransactionRunner

use of org.jdbi.v3.core.transaction.SerializableTransactionRunner in project jdbi by jdbi.

the class TransactionTest method serializableTransaction.

@Test
public void serializableTransaction() throws Exception {
    // tag::serializable[]
    // Automatically rerun transactions
    db.setTransactionHandler(new SerializableTransactionRunner());
    // Set up some values
    BiConsumer<Handle, Integer> insert = (h, i) -> h.execute("INSERT INTO ints(value) VALUES(?)", i);
    handle.execute("CREATE TABLE ints (value INTEGER)");
    insert.accept(handle, 10);
    insert.accept(handle, 20);
    // Run the following twice in parallel, and synchronize
    ExecutorService executor = Executors.newCachedThreadPool();
    CountDownLatch latch = new CountDownLatch(2);
    Callable<Integer> sumAndInsert = () -> db.inTransaction(TransactionIsolationLevel.SERIALIZABLE, h -> {
        // Both read initial state of table
        int sum = h.select("SELECT sum(value) FROM ints").mapTo(int.class).findOnly();
        // First time through, make sure neither transaction writes until both have read
        latch.countDown();
        latch.await();
        // Now do the write.
        insert.accept(h, sum);
        return sum;
    });
    // Both of these would calculate 10 + 20 = 30, but that violates serialization!
    Future<Integer> result1 = executor.submit(sumAndInsert);
    Future<Integer> result2 = executor.submit(sumAndInsert);
    // One of the transactions gets 30, the other will abort and automatically rerun.
    // On the second attempt it will compute 10 + 20 + 30 = 60, seeing the update from its sibling.
    // This assertion fails under any isolation level below SERIALIZABLE!
    assertThat(result1.get() + result2.get()).isEqualTo(30 + 60);
    executor.shutdown();
// end::serializable[]
}