Ankur Mhatre
7b06d653e4
Adds a JUnit test suite (GetVsGetReferenceTest, MergeRefreshTest, OptimisticLockTest, IdentityBatchTest, SequenceBatchTest, AllocationSizeSweepTest, BatchSizeSweepTest) so every surprising behavior described in the three companion posts has a reproducible test, alongside the original CommandLineRunner scenarios. Rewrites all three doc chapters and the README around the new experiments: the get()/getReference() same-session matrix, the merge()/refresh() experiments (including exactly when OptimisticLockException surfaces and a corrected LAZY-plus- cascade merge() result), and two new sweeps (allocationSize, batch_size) for batch inserts.
101 lines
4.0 KiB
Java
101 lines
4.0 KiB
Java
package com.ankurm.hibernatedemo;
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import static org.assertj.core.api.Assertions.assertThat;
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import com.ankurm.hibernatedemo.model.Book;
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import jakarta.persistence.EntityManager;
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import jakarta.persistence.EntityManagerFactory;
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import jakarta.persistence.OptimisticLockException;
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import org.hibernate.Session;
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import org.junit.jupiter.api.Test;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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import org.springframework.beans.factory.annotation.Autowired;
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import org.springframework.boot.test.context.SpringBootTest;
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/**
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* Backs ankurm.com post 4860. Docs: docs/02-merge-vs-refresh.md.
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* Run with {@code ./mvnw -Dtest=OptimisticLockTest test}.
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*
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* <p>The specific thing this test pins down: exactly WHEN the version check fails. It would be
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* easy to write "merge() throws OptimisticLockException" and leave it there; what actually
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* happens depends on when Hibernate performs the check relative to the {@code merge()} call, the
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* flush, and the commit -- and that's worth being precise about rather than assumed.
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*/
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@SpringBootTest
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class OptimisticLockTest {
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private static final Logger DEMO = LoggerFactory.getLogger("DEMO");
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@Autowired
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private EntityManagerFactory emf;
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@Test
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void mergeOfStaleVersionedEntity_throwsOptimisticLockException_andPinsDownWhen() {
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// Seed.
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EntityManager seed = emf.createEntityManager();
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seed.getTransaction().begin();
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Book book = new Book("Clean Code", "Robert C. Martin");
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seed.persist(book);
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seed.getTransaction().commit();
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Long id = book.getId();
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seed.close();
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// Detach at version 0.
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EntityManager loadEm = emf.createEntityManager();
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loadEm.getTransaction().begin();
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Book detached = loadEm.unwrap(Session.class).get(Book.class, id);
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loadEm.getTransaction().commit();
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loadEm.close();
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assertThat(detached.getVersion()).isEqualTo(0L);
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// A second, independent transaction advances the row to version 1.
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EntityManager writer = emf.createEntityManager();
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writer.getTransaction().begin();
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Book row = writer.unwrap(Session.class).get(Book.class, id);
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row.setTitle("Clean Code (2nd Edition)");
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writer.getTransaction().commit();
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writer.close();
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// Mutate the STILL version-0 detached instance and attempt to merge it.
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detached.setAuthor("Robert C. Martin (Uncle Bob)");
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EntityManager em = emf.createEntityManager();
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em.getTransaction().begin();
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Session session = em.unwrap(Session.class);
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boolean threwDuringMergeCallItself;
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OptimisticLockException caught = null;
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try {
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session.merge(detached);
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threwDuringMergeCallItself = false;
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} catch (OptimisticLockException e) {
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threwDuringMergeCallItself = true;
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caught = e;
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}
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if (!threwDuringMergeCallItself) {
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// merge() itself only queued the state transfer; the version check happens at flush.
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caught = org.junit.jupiter.api.Assertions.assertThrows(
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OptimisticLockException.class, () -> em.getTransaction().commit());
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DEMO.info("OptimisticLockException surfaced at commit()/flush time, NOT from the merge() call itself.");
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} else {
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DEMO.info("OptimisticLockException surfaced directly from the merge() call.");
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em.getTransaction().rollback();
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}
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assertThat(caught).isNotNull();
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DEMO.info("exception: {}: {}", caught.getClass().getName(), caught.getMessage());
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em.close();
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// The other transaction's title change must have survived untouched.
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EntityManager verify = emf.createEntityManager();
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verify.getTransaction().begin();
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Book current = verify.unwrap(Session.class).get(Book.class, id);
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assertThat(current.getTitle()).isEqualTo("Clean Code (2nd Edition)");
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assertThat(current.getAuthor()).isEqualTo("Robert C. Martin");
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verify.getTransaction().commit();
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verify.close();
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}
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}
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